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University of Wollongong Thesis Collections
1995
Glazes between 1100[degrees]C and
1200[degrees]C for studio pottery: a systematised
development of raw glaze theory and practice for
once fired, midfire purposes
Ivan Oscar Englund
University of Wollongong
Recommended Citation
Englund, Ivan Oscar, Glazes between 1100[degrees]C and 1200[degrees]C for studio pottery: a systematised development of raw
glaze theory and practice for once fired, midfire purposes, Doctor of Philosophy thesis, Faculty of Creative Arts, University of
Wollongong, 1995. http://ro.uow.edu.au/theses/1753
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GLAZES BETWEEN 1100°C AND 1200°C FOR
STUDIO POTTERY
A Systematised Development of Raw Glaze Theory and Practice
for O n c e Fired, Midfire Purposes
A written submission in partial fulfilment of the requirements
for the award of the degree
I UNIVERSITY Of |
WOLLONGONG
DOCTOR OF CREATIVE ARTS
from
UNIVERSITY OF W O L L O N G O N G
by
IVAN OSCAR E N G L U N D
FSTC ASTC
Faculty of Creative Arts
1995
CERTIFICATION
I certify that this work has not been submitted for a degree to any other university or
institution and, to the best of my knowledge and belief, contains no material previousl
published or written by any other person, except where due reference has been made in t
text.
Ivan Oscar Englund
21 June 1995
GLAZES BETWEEN 1100°C AND 1200°C FOR STUDIO
POTTERY
A Systematised Development of Raw Glaze Theory and Practice
For O n c e Fired, Midfire Purposes
ABSTRACT
This research investigates "middle fire" ceramic glazes in the firing temperatures betwe
1100 and 1200 degrees centigrade (Seger cones 1 to 6). It addresses an area of firing
temperatures that has been largely neglected over the centuries, in contrast to both
earthenware and stoneware about which there is a vast amount of information available. The
research shows, however, that there is evidence of a current growth of interest worldwide in
midfiring for reasons of economy and ecology. The author's long invovement in pottery
extending over forty years positions him well to develop glazes in this study which compare
favourably with those in other temperature ranges.
Of added significance and originality the middle fire glazes have been developed for "on
firing" or "raw glazing" where glaze is applied to the d a m p pot thereby eliminating the biscuit
fire. Researching the literature of ceramic studio work done both in Australia and overseas
has yielded no reference to this method of glaze application at the middle fire temperatures.
The combination of middle firing and raw glaze application is worthy of consideration
because each part of the process saves on fuel consumption. There is a saving in costs for
the potter and there are benefits to the ecology with less fossil fuels used, less greenhouse
gasses created and less contribution to the possible global warming.
The dissertation is of necessity a technical paper put into perspective by a brief exa
the history of glazes, as seen from the viewpoint of a potter as opposed to the traditional
archaeological viewpoint. Early pottery from the Middle East, China, Japan, Korea and
Europe are considered. T h e links between these Asian and European traditions and
Australian ceramics, introduced by Bernard Leach with the publication of his A Potter's
Book, are described as the basis of Australian glaze traditions.
Recipes for raw glazes firing at Seger cones 1 to 6 are listed together with descripti
fired results and Seger formula calculations.
Table of Contents
1
Introduction
2 The Earliest Pottery - A Brief Historical Survey 3
Western History 5
Eastern History 9
European Lustre Ware 22
European Tin Glaze 24
3 Industrialisation and Studio Pottery 26
The Leach Contribution 28
The Australian Scene 30
4 The Middle Fire Glazes 49
5 Working the Seger Formula 55
6 Bentonite and Once-Fired Glazes 61
Raw Glazes for Reduction and Oxidised Once Fired Purposes 69
8 Bibliography
9 Appendix 1 - Glaze Calculations
10 Appendix 2 - Clay
11 Appendix 3 - The Exhibition
1
ACKNOWLEDGEMENTS
Beryl Margaret Anderson
Professor Sharon Bell
Dennis Chapman
Professor Barry Conyngham
Annette Diamant
Lindsay Duncan
Professor Peter Fielding
Dr Bert Flugelman
Ian Gentle
Andrew Hunter
Sandra Indlekofer-O'Sullivan
Elizabeth Jeneid
Daniel Midwinter-Hampton
Dr Sue Rowley
Dr Peter Shepherd
Julia St George
The Walcha Telecottage
Allan and Leslie Wickham
Chapter 1
INTRODUCTION
GLAZES B E T W E E N 1100°C A N D 1200°C F O R STUDIO
POTTERY:
A Systematic Development of Raw Glaze Theory and Practice for
Once Fired, Midfire Purposes
This research investigates "middle fire" ceramic glazes in the firing temperatures
between 1100 and 1200 degrees centigrade (Seger cones 1 to 6). In m y opinion
this area of firing temperatures has been largely neglected over the centuries in
contrast to both earthenware and stoneware, about which there is vast amount of
information available. M y research shows, however, that there is evidence of a
current growth of interest worldwide in mid-firing for reasons of economy and
ecology. Because of m y long invovement in pottery extending over forty years I
a m in a position to authoritatively evolve glazes in this study which will compare
favourably with those in other temperature ranges and that will be as attractive to
potters as are the more traditional glazes in the low fire earthenware area and in the
high temperature field of stoneware. I have therefore extended m y earlier work on
cone 4 glazes to cover the completefiringrange between cones 1 and 6.
Of added significance and originality my middle fire glazes have been developed
for "once firing" or "raw glazing" where glaze is applied to the d a m p pot thereby
eliminating the biscuitfire.M y research into the literature of ceramic studio work
done both in Australia and overseas has yielded no reference to this method of
glaze application at these middle fire temperatures. I regard the combination of
middle firing and raw glaze application as very important, as each part of the
process saves on fuel consumption. There is a saving in costs for the potter and
there are benefits to the ecology with less fossil fuels used, less greenhouse gases
created and less contribution to the possible global wanning.
I regard this study to be an important contribution to the expansion of knowledge
in the very long history of ceramics. This dissertation is of necessity a technical
paper put into perspective by a brief examination of the history of glazes, as seen
2
from the viewpoint of a potter as opposed to the more traditional archaeological
viewpoint. The earliest pottery k n o w n from the Middle East is examined and
contrasted with the Chinese wares from Shang to Ming dynasties, the Japanese
and Korean potteries andfinallywith the European lustre and tin glazed wares.
The Australian colonies depended largely on European ceramic technology until
the publication of his A Potter's Book by Bernard Leach.1 His writings about his
work with H a m a d a in Japan and his o w n experience of stoneware in Britain raised
the Australian awareness of the importance of the Song wares and the place that
high fired wares such as porcelain and stoneware could play in the work of studio
potters. The Leach/Hamada tradition was sewn into the post-war Australian art
evolution by potters such as Ivan McMeekin, Mollie Douglas, Peter Rushforth and
myself. Our collaboration founded the Potters' Society of Australia, a significant
influence in disseminating knowledge to Australian potters and fostering the
growth of serious studio pottery through discussion groups, lectures and
workshops. Each one of our four separate career paths is described. M y special
involvement in mid-fire raw glazing and m y research in developing suitable glazes
forms the focus of this dissertation.
I have used the Seger formula method of evolving glazes and this is described in
detail. I have illustrated its use with an example of a glaze based on a eutectic
which melts at 1160 degrees centigrade the formula of which is 1 C a O , .35 AI2O3,
2.48 Si02- I have then tabled calculations to incorporate bentonite as the key
variable component for glazes to be applied to the leather hard pots, the so-called
oncefireor raw glaze method.
Recipes for raw glazes firing at Seger cones 1 to 6 are listed together with
description of the fired results and the complete Seger fomula calculations for the
above glazes are given as tables in Appendix 1. In Appendix 2 some commercial
clays suitable for firing at these temperatures are discussed together with some
body recipes for potters w h o wish to m a k e their o w n and in Appendix 3 are details
of m y Exhibition at the Bloomfield Galleries, Paddington which showed pots
using some of the glazes from this study.
Old age hath yet his honour and his toil.
Death closes all; but something ere the end,
Some work of noble note, may yet be done ...
(Tennyson)
Bernard Leach. A Potter's Book. Faber and Faber, London, 1940.
3
Chapter 2
THE EARLIEST POTTERY - A BRIEF HISTORICAL SURVEY.
In approaching almost any matter relating to pottery and especially that involving
research there is an overwhelming sense of the vast history of the subject. Making
pottery was one of the earliest crafts, along with basket making, weaving, the
making of weapons, undertaken long ago in prehistory. O n e can speculate with
regard to weapons that it seems likely that a stick m a y have been used for defence
or attack and this could logically have evolved into a spear for throwing or jabbing
by sharpening it into a point. Perhaps by chance it would have been found that the
point could have been improved by hardening in a fire. Further improvements
m a y have followed by attaching a hard, sharp stone flake to the tip to further
improve the efficiency of the spear, and it follows that over the centuries spear
points would be m a d e of bronze then iron and steel.
Similar speculation suggests that baskets probably evolved as containers for food
and the transport of various items. Food m a y have been placed on a bed of grass
or reeds. Possibly by s o m e chance it was noticed that interweaving the reeds
resulted in a firmer grass bed and so a transportable carrier bag evolved. During a
visit to Papua N e w Guinea in 19811 saw such bags being made. Interlacing reeds
or grass was probably the forerunner of weaving of other fibres. Reed mats could
have been m a d e as part of the hut-building process and asfibresbecame available
weaving as w e understand it would have gradually c o m e into being. Making cloth
to augment or replace animal skins as clothing is a likely motivator.
Some authorities suggest that clay may have been used to smear into baskets to fill
the gaps between the fibres to m a k e the utensil more useful for storing small
grains. The next step m a y have been the accidental burning of the basket in the
cooking fire, resulting in the hardening of the clay into a crude ceramic pot. There
is s o m e perception that this m a y have been the case because m a n y of the earliest
pots still in existence are decorated by criss-cross patterns, either incised or
painted with coloured pigments thought to have been related to baskets. Another
suggestion is that a fire m a y have been lit on a clay area and the hardness of the
ground after it cooled could have been observed as useful. Clay was used for
various decorative purposes such as body painting, cave painting and weapon
painting so it would have been a familiar material in m a n y parts of the world.
4
W e s t e r n History
I have used Cox's Pottery and Porcelain1 as m y main reference for this early
history. In addition, m u c h of m y data has been acquired and accumulated along
the way, sometimes serendipitously, over m y years as an artist. For these 'facts'
there m a y be no quotable source.
A s investigations by historians and
archaeologists continue in all parts of the world n e w information is collected. A
great deal of our knowledge of the ancient past comes from the excavations of pots
and pottery shards for, though baked clay or potteiy is comparatively fragile and
easily broken, it will survive better than m a n y other materials as an indicator of a
past civilisation. The question of where pottery was first m a d e will probably
never be answered though s o m e authorities suggest that at least some of the
earliest pottery was discovered during excavations in the 1960s at Catalhuyuk in
Turkey on the Anatolian Plateau. B y reference to the various levels of the
excavations this was calculated to be about 9000 years old. The Encyclopaedia
Britannica3 describes the wares as being a crude soft earthenware and notes that a
more advanced variety of handmade ware dating at about 6 5 0 0 B C has been found
in the same area. This ware was burnished and fired higher resulting in a harder
material. The pots were not glazed but those that were burnished had a sheen on
the surface, achieved by rubbing the clay while it is still d a m p but quite firm with a
smooth pebble or some other very smooth object. The longer the burnishing the
greater the sheen which remains w h e n the pot is dry and after it is fired. Even
today this method is used by some studio potters w h o prefer a natural sheen on the
clay to a glazed surface. This sophisticated treatment of a clay surface in the
Neolithic A g e would seem to indicate that pots had been m a d e for a long period of
time previously, for the method is one that suggests an evolution over time. Also
it is something that is discovered with experience. Again the report that the pots
from these excavations were harder indicating a higher temperature is another
reason for suspecting that their making had been preceded by m a n y generations of
potters w h o had succeeded in some w a y in making their kilns efficient enough to
reach the required temperatures.
The crude, soft earthenware from the digs at Catalhuyuk would point to the fact
that the firing technique was very primitive, probably in some sort of open bonfire
or a simple pit. Even today potters use such methods. In Fiji I saw village
w o m e n fire a single dry pot in a small open fire fuelled by a few coconut husks.
This resulted in a soft porous pot. After lifting it from the fire with a stick the
potter rubbed the interior with resin from a special tree. The resin melted with the
2
Warren E Cox. Pottery and Porcelain, Crown Publishers, N Y , 1949.
^Encyclopaedia Britannica, 1982 edition.
5
heat, covering the clay surface with an impervious layer. This sort of primitive
firing is adopted by some 'pseudo-primitive' m o d e m potters w h o find the results
satisfy the aesthetic goals they set themselves, using pit and sagar firing methods.
The pit firing can result in various 'natural' colours, achieved by the variations of
heat from the burning wood. However, it is amusing to note that often the
inherent properties of 'softness' and fragility of the clay fired in such a w a y are
avoided by a preliminary biscuit firing, perhaps in an electric kiln, and the
'accidental' colours yielded by burning w o o d are augmented by applications of
coloured slips and washes of oxides, particularly copper and iron and a sheen is
added by polishing thefinishedpot with wax.
Cox in his Pottery and Porcelain* noted that A J Butler reported some tiles with a
blue-green glaze and inlaid hieroglyphics m a d e in Egypt about 5500BC. C o x also
claims that Egypt was probably the area where glazes werefirstevolved and used.
This is supported by the fact that blue-green glazes or turquoise glazes have been
the hallmark of all so-called Middle East countries, with examples from Egypt,
Persia and Turkey. In fact even today these coloured glazes are often called
Egyptian blue or sometimes M o h a m m e d a n blue. The turquoise colour in a glaze is
achieved by adding a small amount of copper, in the form of copper oxide, copper
carbonate or even copper metal filings to a highly alkaline glaze. In Egypt and
Arabia, and other arid areas in Australia, Africa and the U S A , there are m a n y
playas and salt pans where brines evaporate and deposit minerals in the form of
chlorides, sulphates and carbonates. It is therefore feasible to consider the
development of primitive glazes and glasses in the Middle East involving the
sodium rich evaporative minerals coloured by copper.
Petrie5 reported very early pots from the Middle East made of fine clay with a
black surface found to be iron ore. Such pots would probably have beenfiredat
earthenware temperatures of about one thousand degrees Centigrade. In
Southwest Iran pottery dating from 3 2 0 0 B C has been found. These goblets,
vases and bowls were mostly painted in a geometric style with dark colours,
probably clay slip or ground iron-rich rocks. Antediluvian archaeological digs
have yielded decorated, wheel-thrown pottery, called 'Al'Ubaid'. According to
the Bible the Great Flood is usually thought to have occurred about 3000BC.
In Europe a great variety of pottery has been found from kitchen middens. Many
of the shapes have rounded or pointed bottoms, suggesting that they were m a d e to
4
Cox, p. 153.
^Flinders Petrie, in Cox, p. 9.
6
sit more firmly on uneven ground or on cave floors. Evidence of these shapes is
universal in early civilisations. Archaeologists pay great attention to the decoration
on pots, perhaps more than to the clays and the making and firing techniques, so
firing temperatures are rarely mentioned. It has been noted through history that
decoration is added to almost eveiy thing that has been m a d e by humans. There
seems to be an inherent need to embellish an otherwise perfectly functional article,
be it a weapon, a shelter, clothing or a pot. Suzanne Foley sees clay as a
particularly seductive material and feels the, "expansion of work in ceramic art and
the variety of subject matter treated can be attributed in large part to the immediacy
and intimacy of clay as a medium".6 The soft, tactile surface of a newly m a d e pot
evokes an almost irresistible urge to add marks to it in the form of incised circles
or bands of coloured slip or pigment, especially if the pot is on a wheel, whether it
be the slow wheel often used by ancient potters as a convenient w a y of revolving
the work or on the more recent potter's wheel.
In Egypt, good hard-fired earthenware has been reported from around 3100BC,
decorated with white slip on a red body. This indicates a ware that m a y be less
porous than other earthenwares but again there is no indication of a firing
temperature. The decoration ranged from stylized animals and scenes to plant life
and figures. U p to 3 0 0 0 B C in the Aegean and Greece handmade red earthenware
with incised decoration, was sometimes burnished. The shapes, some with long
spouts, had their surfaces treated with terra sigillata and the decoration was of
simple geometric patterns.
There are many references to the influence of metal objects on pottery shapes both
from Europe and from China but C o x 7 speculates that in all probability the first
metal shapes were influenced by those of pottery. It seems logical that our
ancestors would have learned h o w to shape the more easily worked clay before the
m u c h more difficult metal. Digs of the Middle Bronze age (2000-1580BC) have
revealed pots of a grey body with the plant and marine motifs painted in a very
stylized manner. These pots appear to have been m a d e on a 'fast wheel', that is a
potter's wheel revolving in such a manner as to leave the hands free. This was in
Crete and is thefirstreference to a true potter's wheel. Like pottery itself there is
no factual evidence of where thefirstwheel appeared. It is generally assumed that
it c a m e into being in various places and that the idea sprung from the fact that the
hand building of pots was facilitated by placing the ware on some sort of stone or
board so that it could be revolved slowly by hand as the pot grew. This saved the
6
Foley, in Clark, p. 119.
Cox, p. 104.
7
7
potter the trouble of walking around the pot. Its evolution only needed the potter
to balance the flat stone or board on a point so that it would be pulled around by
hand sufficiently fast to allow a true 'throwing' motion. The simplest motive
power was of course the hand, either the potter's o w n or that of a helper. In Japan
even today the potter's wheel is turned with a stick inserted in holes in the rim of
the wheel head. W h e n speed is attained the stick is put d o w n and the clay
manipulated. W h e n the speed slows the stick is inserted again and the speed
increased. A great improvement occurred when the wheel head was attached to a
shaft with a flywheel that could be kicked around by the potter's foot so as to
maintain a constant speed and leave the hands totally free. Over a long time the
only real change has been the provision of external power to drive the wheel,
human power, water power, motor power and electrical power.
During the Late Bronze Age (1580-1100BC) the emphasis in Grecian vessels was
again on stiff shapes based on metal models, with decoration adapted from wall
painting. Later, in the Early Iron A g e (1100-725BC), the development of the
large amphorae and kraters reached its peak. These were for wine use and the
shape was that of a swelling bulbous body with an excessively narrowed foot, and
at the neck was a pair of decorative handles, too small to be useful. For more than
two thousand years there has been an almost universal adulation of Greek pottery.
Walker proclaimed that Greek pottery was "the greatest art of the ceramist ever
k n o w n on this earth".8 Certainly the painting was excellent and deserves praise
but some potters feel uneasy about the shapes. C o x devoted a page or so to an
analytical criticism setting out the weaknesses of the design of Greek pots. These
included weak and badly placed useless handles, spouts that were too wide to pour
properly, excessively narrow bases necessitating the addition of "flat attached
bases which spoil the rhythm of the curves",9 and are easily broken, horizontal
handles indicating two-handed drinking and so on. With regard to the painting,
whether it is "black figure" or "red figure", he is lavish in his praise. It is
interesting to note that none of the Greek potters signed their work as makers but
m a n y of the painters did, including Cleitias, Ergatimas, Execias, Amases and
Nicosthenes. During the Classic period to 3 3 0 B C and the Hellenestic, from 330
to 3 0 B C , a decline in the quality of painting led to the production of plain
blackwares which were, according to Cox, "undistinguished"10.
Of the pottery of Italy in the period 1200BC to about 2100AD Cox writes, "If
Greece started the trend towards the worst of bad taste, Italy carried it on to its
8
Cox, p. 51,
Cox, p. 51.
10
Cox. p. 54.
9
ultimate conclusion".11 In Villanova pottery was a crude ware with crude
decoration. The Etruscans showed what was possible with a gigantic pottery
warrior, about eight feet high, made in about 500BC. However, their main
pottery business was copying little Tanagra figures and making objects, "of unfelt
mythological subjects, girls lounging in ornate grandeur among flowers, ribbons,
pet animals and other sloppy ideas of design".12 Perfume bottles were made of
whole busts of w o m e n surrounded by scarves and swirls. Hannover wrote of
them, "The objects are considered to be among the greatest treasures of the
M u s e u m s that possess them", (the Louvre, the British M u s e u m and the Berlin
M u s e u m ) , but he adds, "although they are in every way more curious than
beautiful."13
EASTERN HISTORY
China-from Shang to Ming
O n the other side of the world in China at A n - Y a n g in Honan province and in
Kansu province Andersson 14 found large wheel-thrown pots of highfiredbrown
clay. These were at first claimed to be from the period 3 2 0 0 B C to 2 9 0 0 B C but
later Liang Ssu-Yung estimated that they were probably made between 2500 and
2000BC.
Betts has dated
some hard white pottery, also at An-Yang, at
1800BC. 1 5 These claims are significant in comparing Eastern and Western
cultures. Whereas all the excavations in Europe and the Middle East have revealed
earthenware of various types the early A n - Y a n g finds have been described as
"hard baked" ware and "hard white pottery", indicating that at that time China had
the means, the clay and the kilns to produce wares assumed to be stoneware.
In China, in the history of the pre-Han there were four periods-the Hsia, Shang,
Chou and Ch'in. The Hsia, about 2200BC to 1700BC, is regarded as legendary.
A good deal is known about both the Shang (1766 - 1122BC) and the Chou (1122
- 249BC). The Chou period occupied the longest period of China's history. The
Ch'in (249 - 2 0 7 B C ) then took over and though it dominated for a very short
period, was of great importance. The Ch'in Emperor unified China for the first
time, the Great Wall was completed and a system of weights and measures
introduced. This was also a significant period from a ceramics history point of
view. It was customary to bury high-ranking persons with all their possessions,
n
C o x , p.
Cox, p.
13
Cox, p.
14
Cox, p.
15
Cox, p.
12
65.
67.
71.
20.
21.
9
including living wives, concubines, servants and animals. After Confucius
stopped this the custom was still followed but instead of live burials pottery
models of everyone and everything were substituted. M u c h of the knowledge of
those times and customs has become available to us through excavations of burial
sites. These were found w h e n railways were built and earthworks and cuttings
revealed some of the tombs. The discovery and excavations near Xi'an which
brought to light the n o w famous "Entombed Warriors" was a most exciting event.
Outside Xi'an some peasants drilling for a well near a large m o u n d accidently
found the site of what is n o w k n o w n to be where the warriors and horses were
buried to protect the tomb of the Emperor Ch'in. I was in China in 1978 with a
party of Australian potters and at that time the early excavations had been stopped
after the recovery of about eight warriors and three horses. This was to allow a
large building to be erected to completely cover the site. The policy of the Chinese
seems to be to build a m u s e u m on the actual site instead of transferring artefacts to
some existing museum. 1 6 All that existed on the site in 1978 was a small bamboo
building in which I saw two of the warriors and one of the horses, which at that
time tourists were able to touch.
It was estimated that some eight thousand
warriors were buried there and I understand that n o w the excavation is complete
the ranks of warriors stand in order in their original formations and the damaged
figures have been repaired. The warriors are larger than life size and are modelled
in great detail with heads thought to be accurate portraits of actual soldiers. It is
thought that each figure m a y have been modelled in a dark grey clay then a small
kiln built around it for firing in situ, thereby overcoming the difficulties of
handling such large pieces. Near Xi'an there is also an excavated stone age village
dating back 6000 years. It too is a m u s e u m on the actual site and contains about
six potter's kilns which could still befiredtoday.
The Han dynasty, from 200BC to 220AD, made contact with the West. The
Chinese established an embassy on the Persian Gulf, trade in iron and silk was
established with the R o m a n s and Buddhism was introduced from India. The
pottery was strong in design and making. It was fired to a high temperature, some
of it of a porcelaneous nature in that it contained kaolin. S o m e of it was unglazed
while a great deal of it was glazed with a simple alkaline glaze which was
transparent and the colours varied from yellows to browns to copper greens.
According to C o x the glaze was introduced from the West through trade. H e
points out that R o m a n jars were traded into China and they exhibit a similar glaze.
C o x maintains that this was the first glaze used in China. 17 There was a
^The immense building was constructed of Lysaght Steel from Wollongong.
17
Cox, p. 75.
10
development of shapes from the early Shang and C h o u pots and the number of
articles m a d e was greatly increased. Large numbers of wine jars survive perhaps
because they were buried with the dead. Other pots were incense burners, water
droppers for use in writing and painting, storage jars and models of buildings,
farm yards, horses and other animals. C o x shows photographs of the first
porcelaneous pottery consisting of vases of a grey ware with yellowish or greenish
glaze.
Personally I am uneasy with Cox's ready acceptance that the Han pots were glazed
with the "simple alkaline glaze"18 from the West. The fact that the pots were fired
high enough in the kiln to become stoneware and porcelain indicates to m e that the
glaze could be a primitive stoneware type. The Chinese kilns were fired with
wood and the insides of the kiln become coated with a glaze formed as fly ash
settles on the walls and melts at stoneware temperatures. This type of glaze is
typically yellowish or brown or green. Unglazed pots are certainly affected in
exactly the same way. The H a n pots I saw in China had this glaze. It was so
typical of wood firing that I never thought of any other explanation.
Modern potters use this ash glazing method, especially in large single chamber
kilns called by the Japanese anagama
or 'cave kilns'. These are fired for m a n y
days, allowing the ash deposits to build up. The effect can also be achieved on
pots fired in any kiln without longfiringby sprinkling wood ash on the pot while
it is still wet. Perhaps the simplest of all stoneware glazes consists of 5 0 % each of
wood ash and clay. Later, in T'ang times m a n y of the famous horses, camels and
other animals were glazed with soft glazes, not alkaline, but those based on lead.
Nigel Wood19 in his book Oriental Glazes maintains that early Chinese glazes
were in fact the ash glazes consisting of either equal parts w o o d ash and clay or
with some variation in the proportions. I have already noted that Chinese kilns
were fired with wood. The wood was pine and pine ash is m u c h more fusible
than that of most other woods. O n e of the most useful oxides used as a glaze flux
is lime (CaO) and w o o d ash is high in lime. A glaze consists of a flux, alumina
and silica. Clay is composed of alumina, silica and water so mixtures of ash and
clay have the right ingredients for a glaze though not necessarily in the ideal
proportions. These glazes usually run if oveifired due to a lack of silica. W o o d is
of the opinion that most early Chinese glazes were m a d e of mixtures of clay and
lime. T h e clays were highly silicious and the lime was used either as crushed
18
Cox, p. 157.
Nigel Wood. Oriental Glazes. Pitman, London, 1978.
19
11
limestone or slaked lime. W o o d shows a photograph of a pot m a d e between
1 0 0 B C and 1 0 0 A D which illustrates, even in black and white, the thick flowing
glaze in which the flow has been controlled by deep parallel grooves and ridges.
The pot is m a d e from a clayrichin iron and impurities and W o o d suggests that the
glaze recipe would have been the body clay and lime in about 2:1 proportions.
S o m e of these early pots have glazes that are quite dull and almost matt in
appearance, typical of glazes that are too high in calcium. W h e n in China I visited
several T a n g dynasty kiln sites and the shards of the high iron glazed ware, the
blacks and browns, which lay around were usually typical of this high lime
mattness. The large amount of lime, too m u c h to enter into a proper glass melt,
allows the excess to crystalise out in cooling.20
The 'Six Dynasties' and the Sue periods lasted from 220AD to 617AD. There was
a development of the animal models and in particular the horse which was n o w
well-modelled and vigorous. H u m a n figures representing merchants, musicians,
dancers and servants appeared in great numbers. T h e pots continued the H a n
shapes but often became over-decorated with applied ornament.
The T'ang period from 618 AD to 906AD was one of great achievement in all fields
of art. It was a period of great painting, the development of w o o d block printing
and the writing and poetry were unsurpassed. Pottery techniques also advanced,
the pots being lighter and thinner and very high fired. At last C o x mentions shards
of porcelain with a feldspathic glazefiredat high temperatures at a site dated in the
9th Century.21 T h e glazes were white, celadon green, brown, black matt and
some with bluish tinges. There is also mention of a "tea dust" glaze which is a
typical high-fired stoneware glaze with high lime content which crystallizes out on
cooling to form yellow green pyroxene crystals. The Chinese tea (and Japanese
tea) is green, hence the n a m e of the glaze. Again this is evidence of the use of a
very high fired glaze. During the T'ang times there appeared also what Walter
Hochstadter22 described as the first of the "transmutation" glazes, the Juns. T h e
Jun colour is a blue that forms with certain material combinations and the right
firing, the colour derived from the optical effect of suspended particles rather than
by a pigment or oxide. Potters call it an opalescent glaze perhaps because of the
2u
W o o d draws attention to the well-known eutectic of lime, alumina and silica having the
formula of CaO 23.5, AI2O314.75 and Si02 62.0. A recipe expressed in parts by weight
would be kaolin 30.4, lime (calcite or whiting) 33.6 and quartz 36. Many potters use what is
called the "equal parts" recipe i.e. whiting 1, clay 1, quartz 1. The method of converting the
formula to a recipe is dealt with later. The eutectic noted above is supposed to melt at 1170° C
but is probably better at 1200° C.
21
Cox, p. 113.
22
Cox. p. 174.
3 0009 03155620 7
12
similarity to real opals although the opalescence bears no chemical similarity to the
gemstone. The pots of the T'ang continued to develop. Already strong shapes
became even more elegant. The famous T'ang horses were more finely modelled
and there were more human figures of both men, w o m e n and warriors. Vases,
wine jars, ewers and bowls were n o w glazed in the newly-developed high
temperature glazes. The Chinese appreciated the beauty of the pottery and Cox
includes a verse by the poet Hsu Y e n which was written about some cups made
for the Emperor:
Like bright moons, cunningly carved and dyed with spring water;
Like curling disks of thinnest ice,filledwith green clouds;
Like ancient moss—eaten bronze mirror, lying upon the mat;
Like tender lotus leaves, full ofdewdrops, floating on the riverside!73
Despite wars, internal conflict and conquest by the Tartars and Mongols, the
pottery produced during the reign of the Song Dynasty ( 9 6 0 A D - 1 2 8 0 A D ) has
been universally acclaimed as the finest ever. In m y opinion the continuous
development from the earliest times in glazes reached a peak that has never again
been equalled. S o m e of the shapes are overdecorated by modern standards but for
potters the glazes c o m m a n d the highest admiration.
The greens of the
Lung'Chuan celadons are rich and unctuous. The Chuns and the Copper Reds
were well-developed glazes and the methods of working and firing of kilns were
ideal for the results. The Song potters used the materials available in the most
direct w a y to achieve the results most suited to them, working in a very direct
way. Western potters today do not have the benefit of the centuries of continuous
development of the Chinese but m a n y have adopted in some form the ideas of
Eastern ceramics.
Cox simply states that the glazes in the late T'ang time and in the Song were
feldspathic. In contrast W o o d 2 4 states categorically that Chinese glazes were
never based on feldspar, which is a modern European tradition. H e attributes the
success of the Song glazes to the development from clay-lime glazes to what he
calls lime-alkali glazes. It is a well-known fact that while glazes can be made with
only one flux in the formula m u c h better glazes are achieved with the introduction
or two or more fluxes. The Song glazes have been analysed and show between
four and seven percent of potash and soda. This is what has caused C o x to call
them feldspathic glazes on the assumption that these oxides must c o m e from
23
24
Cox, p. 124.
Wood, p. 56.
13
feldspar. However, W o o d concludes that the potash found in the analysis in fact
comes from its inclusion in Chinese materials and in the potash mica called
sericite. A s the glazes were still mixtures of the body clays and other materials the
mica would be a natural and accidental inclusion. Chemical analysis can indicate
the presence of potash but cannot show from what material it is derived. The fine
mica would have m a d e the clay m u c h more plastic and ideal for throwing. The
large amount of clay in the glazes m a d e them ideal for application to the leather
hard pots before firing, a technique sometimes called raw glazing which was
always practiced by the Chinese.25 The technique eliminates a first or biscuit
firing and is also k n o w n as 'once firing' or 'single fire'. It is strange that these
beautiful pots were m a d e at a time w h e n the country was far from peaceful, there
was m u c h internal conflict and intrigue and the threat from the Tartars became a
reality. T h e Song rulers were forced to cede territory and m o v e South. Soon after,
the Mongols and Jenghiz Khan invaded, the conquest became final in 1 2 8 0 A D
with the last of the Song Emperors throwing himself in the sea in despair and
Kublai Khan became emperor of the whole of China. It is probable that for a time
these wars cut off the foreign influences from the West which had been growing
since the H a n period and m a y have therefore compelled Chinese art to fully draw
upon its o w n Chinese resources.
It is not my purpose to rewrite the entire output of the Song potters. Accepting the
views that the Song were supreme potters I can only briefly note some of the
directions they followed especially with glazes. The early Ying Ching porcelain
was m a d e of hard white vitreous body and the pale blue glazes were coloured by
very small additions of cobalt. The imperial wares k n o w n as K u a n Y a o were
often m a d e of dark brown clay with glaze colours of deep green, 'moon white',
pale blue and bluish or greenish colours tinged with red. Crazing in the glaze was
beginning to be controlled into both 'crabs claw', that is large crackle and 'fish
roe', which is very small crackle. From our Western point of view crazing is one
of the faults of glazes. It appears after firing as a m a z e of cracks in the glaze. It
results from the fact that the glaze and the clay body have had different coefficients
of expansion. While the glaze is fluid, at the top firing temperature, it fits onto the
clay with no problems but as the ware cools and the glaze freezes into a hard glass
it has greater shrinkage than the clay and it cracks under the strain. The problem
is solvable by modifying either the glaze recipe or the clay body. Crazing is more
of a problem with porous earthenware pots as the crazed glaze allowed moisture to
seep through but is not a practical problem with stoneware and porcelain which by
25
During the Industrial Revolution with the division of labour in factories biscuitfiringwas
introduced.
14
definition have vitrified bodies. A s stated above the crazing can be in a fine pattern
or a large one. The Chinese with their undoubted technical ability found ways to
overcome this "fault" but also realised its potential as a decorative device in its o w n
right. The change of description from "crazing" to "crackle" helps too. The
crackle can be evident w h e n the pots c o m e from the kiln or it m a y continue to
develop literally for years. Its decorative effects are often augmented by placing
the pot in a dye bath or by applying ink, neither of which are inherently pottery
techniques. The colouring of the crackle occurs more naturally with the pot's use
which causes impurities to settle in the craze pattern.
The glazes we call celadons of the Lung-Ch'uan kilns (and others) deserve special
mention as they present a very good example of the ability of the Song potters to
maximise the inherent possibilities of their materials. The kilns were probably
started in the 9th Century and during the Song period these green glazes were
continually improved. Anecdotally it is reported that the green colour of the ware
was later called "celadon" after the clothing of that colour worn by a shepherd in a
play in 17th Century France The n a m e is n o w used world wide. The colour is
achieved by a small amount of iron oxide in the glaze and by the manipulation of
the fire in the kiln. M a n y clear or transparent glazes can be coloured by an
addition of red iron oxide (Fe203). Fired in an oxidized atmosphere in the kiln the
addition of about 1 % F e 2 0 3 will fire to a pale amber in some glazes and larger
amounts m a k e the glaze darker until with 1 0 % and even more the colour will be a
brown of s o m e kind. Oxidation in the kiln exists w h e n there is sufficient air
admitted to burn the fuel fully and efficiently and the oxide remains unchanged as
Fe203. However with approximately 1 % F e 2 0 3 the colour can be changed to the
green of celadon by a reduced atmosphere, that is, where the air supply is reduced
to m a k e an inefficient flame starved of oxygen. This flame will take oxygen from
any source and in this case attacks the iron oxide and removes some of the oxygen
thereby changing the F e 2 0 3 to F e O and with it the colour from amber to green.
The Lung-Ch'uan celadons not only have the colour but have a soft, thick, tactile
appearance called by some 'unctuous'. Mere green is not necessarily celadon in
the view of m a n y potters and collectors. The green can vary from a bluish green
("blue like the sky after rain")26 through greyish greens to olives and yellowish
green. For s o m e reason the more blue the celadons are the better they are
considered. Most modern celadons are achieved by the addition of iron oxide to a
transparent glaze but the Song potters used glaze materials that had in them small
amounts of iron oxide and they learned h o w to exploit this in the most magnificent
and appropriate way. Even a transparent glaze fired in reduction on a dark clay
26
Cox, p. 141.
15
body will dissolve enough body iron to become green. The Song potters worked
with the celadon glaze until it fulfilled their ambition to make it imitate jade. It was
described at the time as "jade green". M u c h of the decoration was incised,
moulded or modelled before glazing and where the glaze ran into the deeper marks
the colour was darker and richer.
The Jun glazes with the addition of small amounts of copper oxide became more
colourful and descriptions from that time list such variations as "rose purple",
"cherry-apple red", "aubergine purple", "plum-bloom green" and "sky blue".
B r o w n glazes coloured by large amounts of iron oxide continued to be used.
These w e n o w k n o w generally as 'temmoku' which is the Japanese word for
them. These high iron glazes can be black, brown, purplish brown, have flow
patterns called 'hares' fur or segregations of iron called 'oil spots'. This dark
brown glaze was also used in a most decorative w a y on the wares k n o w n as Tz'u
Chou where the glaze was applied to the unfired body and then the glaze was cut
back to the clay in vigorous patterns. Pots of this type are some of the most
beautiful of all Chinese wares.
The Song potters also produced a ware called Ting which featured a reserved
cream, almost matt glaze. The cream colour was achieved because of a small
amount of iron oxide in the glaze probably as an impurity in the clay used and the
wares would have been fired in an oxidizing atmosphere. A reducing atmosphere
would have turned the glaze towards the celadon colour. The Ting ware was
interesting too in that m a n y of the bowls were fired upside down and the unglazed
edge was later covered with a metal rim.
The Ming period, another one of the great periods of Chinese art, ran from 1368—
1644AD. The Yuan era connected the Song to the Ming in which the art traditions
were continued. There were important happenings in that the trade routes in the
Middle East were made safe and there was considerable interchange between the
Arabs and the Mongols.
The purity of the Song pottery is regarded as unequalled and the Ming in many
ways continued the fineness of the wares and continued to improve the quality of
the porcelain body which became extremely hard, pure white, translucent and
completely vitreous. It should be noted that porcelain is only translucent in certain
thicknesses. The Chinese paid no particular attention to translucence realising that
a thick section of porcelain was still porcelain despite the lack of translucence.
Ivan M c M e e k i n 2 7 once told m e that the Chinese had no word for translucence in
2
^Ivan McMeekin, private conversation.
16
any case. Crackle glazes were perfected in Ming times and coloured glazes were
popular. C o x states that the white glaze was coloured with manganese for violet,
copper for turquoise, green and red, iron for "dead leaf brown and antimony for
yellow.28 I disagree with C o x about the yellow. The yellow resulting from the
use of antimony does not withstand the high fire—what the French call the
"grande feu" of 1300°C and above—as is usually indicated on the product by the
manufacturer. Potters making earthenware can prepare the yellow stain by mixing
and roasting antimony, white lead and tin oxide then grinding and washing the
resulting mixture. The colour is what the paint manufacturers call Naples Yellow.
The stain is very good at low temperature only. I contend that the Ming yellow is
fired on the porcelain at a lower temperature in a subsequent firing. I always tried
to m a k e yellow glazes in m y stoneware pottery, remembering the two beautiful
yellow vases in the Kent Collection in the National Gallery of Victoria, but I did
not succeed. M y yellows based on iron oxide were always green or olive because
I have always fired in reduction, whereas the "Old Seto Yellows" of Japan are
actually celadons fired in oxidation. W h e n I was in China I m a d e constant
enquiries about the composition of the yellow pots I saw but usually received no
real answer because the guides and the m u s e u m attendants did not have the
necessary technical background. While in Peking (Beijing) our group naturally
visited the Imperial Palace (The Forbidden City) and were received by the Director
of the Ceramics Collection. In his office w e drank Chinese tea from yellow bowls
decorated with green dragons - Imperial wares from the 17th Century. In one of
the large pavillions housing the ceramics was an exquisite small porcelain bowl,
pure white inside and pure yellow outside. I put m y question to the director w h o
examined the information about the bowl and told m e that it was a Ming bowl
m a d e in Peking and then sent to another city for the outside to be glazed with an
antimony yellow! Chemists and potters have solved the problem of a high fire
yellow stain but it has no antimony in it but is made of vanadium and tin and it is a
very modern stain. Stain manufacturers still make the antimony stain but warn that
it is only useful up to a little over 1100°C.
The copper reds were developed, under-glaze colours perfected and enamels for
on glaze (that isfiredon to the finished pot at low temperatures) became popular.
Gradually the wares became more ornate and towards the latter part of the Ming
they took on the over-decorated nature associated with the later so-called
'decadent' periods. C o x quotes an amusing anecdote regarding the popular blue
and white jars popular in the West because of their primus blossom design and the
fact that they contained ginger. A collector said that by simply removing the
28
Cox, p. 132.
17
ginger the "jar became a Ming pot in an instant!"29 The Ming saw the blue and
white wares reach an almost perfect state. Their popularity has continued until the
present not only in China but in most factories all over the world.
Ming wares were many and varied and were produced in vast quantities for the
Imperial Household. C o x mentions that in the year 1554 the Imperial order for
one kiln included 265,350 bowls with dragons in blue; 30,500 plates; 6,900
bowls and so on. 30 A large part of the Ming wares collected and recorded are in
fact either Imperial wares or m a d e for the rich and noble. However there were
also millions of pots m a d e by village potteries for the use of the c o m m o n people
and it is possible in China to find large hills composed almost entirely of Ming
shards and kiln wasters. Near Ching te Chen I acquired two broken bowls of the
14th Century called 'Village Ming' which have free blue brushwork on a
translucent white glaze.
Japan.
The earliest pottery in Japan is called Jomon. The n a m e is said to refer to the
decoration which was made by impressing ropes or cords into the wet clay. The
ware was heavy and clumsy and unglazed but showed the ability to organise
complex decoration. Jomon wares were m a d e from about 1500BC until about
200BC.
The Jomon was replaced by Yayoi, a reddish-brown pottery, very fine, and
whereas the Jomon pots were hand built the Yayoi were mostly made on a pottery
wheel. O f particular interest were the clay figures called Haniwa m a d e to be
placed in tombs. Haniwa sculptures included animals, houses and boats and have
contributed to our knowledge of the social life of the time.
A new type earthenware replaced the Yayoi. It was still unglazed but it was very
hard indicating superior kiln design and higher temperatures. Tadanari Mitsuoka31
in his book Ceramic Art of Japan states that this superior knowledge came from
the continent. There were two types of kiln, anagama and noborigama. The
anagama (cave or cellar kiln) consisted of a very large chamber for the ware with a
very efficient fire box at the front. The kiln was usually built on a slope to aid
draught. The noborigama or sloped kiln was a development of the single chamber
kiln in that the shape evolved to become a series of chambers interconnected up the
29
Cox, p. 160.
30Cox, p. 182.
31
Tandanari Mitsuoka. Ceramic Art of Japan. Japan Tourist Bureau, Tokyo, 1953.
18
slope,firedinitially with afirebox at the bottom. W h e n the first chamber reached
temperature the kiln was stoked with wood through a series of holes in the side of
the kiln. This side stoking was continued at each succeeding chamber up the hill.
It was an efficient w a y of firing. Such kilns still exist in China; Korea and Japan
and some artist potters in Australia have also built similar kilns. The kilns were
inu-oduced into Japan by way of South Korea. The pottery was called Sue and the
kilns were introduced at around the end of the H a n dynasty in China. The Sue
tradition was widespread and lasted almost to the 12th Century.
I was fortunate to have seen and handled pots in the collection of Toyo Kaneshige
at this house in Bizen in the early sixties. Kaneshige's collection included Jomon,
Yayoi and Sue wares. Mitsuoka maintains that the Sue tradition lived on in the
famous Bizen wares, the Shigaraki wares, the T o k o n a m e wares and the T a m b a
wares. These kilns, and others, yielded unglazed wares dependent on the
accumulation of ash melting on the pots during firing for decoration. They are still
operating and are popular places for potters to visit from all over the world.
From the time of the Sue wares almost to the Meiji period there is no doubt that a
and ceramics in Japan were dominated by all things Chinese though there is
general agreement that these Chinese influences were modified by Japanese tastes
and preferences. Peter S w a n n 3 2 in his Art of China, Korea and Japan makes a list
of the various periods in Japanese art from the Sue and Great T o m b s period (to
about 5 0 0 A D ) including in historical order Asuka, Nara, K o m i n , Heian,
Kamakura, Muromachi, Edo and Meiji. In all of these can be traced the modifying
Japanese taste upon Chinese originals. Great pottery centres arose at Seto,
Karatsu, Kyoto and Satsuma which m a d e stoneware products in great quantity,
still based on Chinese influences. The glaze k n o w n as Shino, m a d e of a special
kind of feldspar, was used widely. Its near companion, Oribe ware with its
copper green and white glazes, was regarded as being influenced by the Ming
three-coloured wares.
The main change in Japanese pottery resulted from the introduction of porcelain.
General Toyotomi Hideyoshi invaded Korea in 1592 and again in 1597 and upon
his return brought a group of Korean potters, probably prisoners, back to Japan.
Their leader was Ri Sanpei and they settled on the island of Kyushu. Kyushu is
the closest Japanese island to Korea and all the attacks on Korea were launched
from there. The Koreans set up kilns and discovered a satisfactoiy porcelain clay
called A m a k u s a stone at Izumiyama near Arita in about 1616 and so the Japanese
32
Peter Swann. Art of China, Korea and Japan. Thames & Hudson, London, 1963.
19
porcelain industry w a s born. The city of Arita is still a very large porcelain
producer but the wares are generally k n o w n as Imari wares, named after the port
from which they were exported. Arita produced fine porcelain in the blue and
white tradition and later wares decorated with coloured enamels. The works of the
Kakiemon family were highly prized for the delicate brushwork on the milkwhite
glaze. The family continues to live there to this day. Nabeshirna ware was
another veiy highly regarded because of the excellence of the enamelled porcelain.
It was never exported as it was m a d e only for a noble family. Porcelain factories
rapidly spread to m a n y other parts of Japan.
Not many individuals are mentioned in the early days of porcelain production but
the Japanese revere the work of Nonomura-Seiemon k n o w n as Ninsei. H e was a
famous artist w h o set up a kiln in Kyoto and produced wares for the tea ceremony,
and he was succeeded by a pupil, Ogata Kenzan, whose work as described by
Tadamari Mitsuoka, "consists in the freedom, gracefulness, and gentleness of
expression which is a direct reflection of Japanese taste"33 His work was widely
copied by several factories.34
After the Meiji restoration in 1868 Japan went through a period of rejecting
everything Japanese in an attempt to become a 'modern' nation but later turned
back to her o w n art. The influence of the Japanese crafts on artists all over the
world has been profound.
Korea
Korea, a peninsular connected to Manchuria, was naturally and easily influenced
by Chinese pottery, but invariably distinctly Korean characteristics appeared and
Korea m a d e a definite contribution in allfieldsof art including ceramics". The
Korean potters evolved a decorative technique called hakeme which involved a
swift brushing of white slip onto a pot, leaving the brush marks. T h e pot was
then glazed with a transparent glaze. Yanagi notes that the brushes could be made
of hair, hemp,ricestraw or grass. The technique is still m u c h used on the country
wares in rural Japan and I have seen the great H a m a d a collect a handful of grass
outside the studio to create the hakeme effect. The word "hakeme" actually means
brushmark. The beauty of hakeme is said to depend on an almost unconscious
application of the brush with a swift direct sweep. It is thought that originally the
white slip wa s used (and still is) to cover a dark or rough clay and potters
^Mitsuoka, p. 57.
It is interesting too that Bernard Leach learned his pottery from a potter called Ogata Kenzan
the sixth so Leach could have called himself "Kenzan die Sevendi".
34
20
discovered the beauty of this hakeme technique. The superb painted decoration in
iron pigment continued through the Yi period. Early in 1994 in N e w York I was
fortunate to see a comprehensive exhibition of Korean pottery at the Metropolitan
M u s e u m of Art. The pots were mainly the celadons, the special grey-green
already mentioned and the jars of the Yi period decorated with iron oxide
brushwork. Though Korean pottery is noteworthy most of the modern pots
appear to be m a d e in factories. Only near the ancient capital did I find a small
pottery with a couple of small climbing kilns producing the unglazed wares
reminiscent of the Silla period35 and recently I have noted articles referring to artist
potters setting up studios in various locations.
^^The pottery was called the Silla Pottery
21
E u r o p e a n Lustre W a r e .
From R o m a n times to 18th Century Europe all pottery was earthenware and C o x
almost dismisses it as being unimportant except for a couple of very interesting
developments in glaze techniques. The first of these is lustre. The other is tin
glazing which will be dealt with later.
Lustre is an on-glaze technique which ionises on an already fired glaze a very thin
layer of metal that imparts an iridescence to the colour. It was perfected in Islamic
counuies and in 7 1 2 A D was introduced to Spain when M u s a b. Nosair the Arab
conquered Spain. It flourished as a dominant raw glaze technique and the
Hispano-Moresque wares constitute one of the great pottery arts. The glaze was
used to best advantage on the large platters decorated with simplified animal
designs and coats of arms. Lustre glazes can be gold, silver, blue, red or yellow.
Sanders in his book Glazes for Special Effects^6 noted that the glazes m a y have
originally been used as an inexpensive substitute for gold and silver wares. The
lustre of the Middle eastern potters and (subsequently) the Spanish, was produced
by painting the metallic pigments in the form of a paste on to a glazed surface and
then refiring. Sanders37 states that the ware should be of soft earthenware and the
glaze should be a lead/soda type. H e also notes that high fired wares can be
lustred as well. The lustre pigments are composed of earthy materials such as
ochre, burnt umber and burnt siena all of which are partly iron and manganese
oxides. Silver carbonate is added to the earth paste and it can give yellow, gold
and bronze colours. Copper carbonate results in red and ruby colours as well as a
metallic copper. The ware isfiredin a kiln, often a special one, to the very low
o
temperature of cone 022 which corresponds to 605 C. With the kiln at dull red
heat smoke must be created in the chamber. This is done by dropping combustible
materials into the kiln. These can be moth balls, sawdust, oil, rags or w o o d
soaked in oil. W h e n cool the ware is washed to remove the sooty paste to reveal
the metallic colour.
It should be noted that the above description applies to the traditional reduced
pigment lustre. Modern potters produce the effect m u c h more easily because
commercial lustres are produced as self-reducing liquids which are painted or
sprayed on to the ware and fired to cone 020 (650°C) or 017(730°C) in an
oxidizing atmosphere.
36
Herbert H Sanders. Glazes for Special Effects. Watson-Guptil, N Y , 1974.
^Sanders
22
The early lustre wares in Spain were Islamic in every way. T h e painting and
decoration had been transported with the Moors and featured arabesques, 'tree of
life' palm trees and with Islamic calligraphic inscriptions. C o x notes that
sometimes Spanish inscriptions were misspelt by Moorish workers and those in
Maghribi calligraphy were misspelt by Christian workers. The Moors were driven
out in 1610 and thereafter Gothic foliage, flowers and 'chain mail' patterns in great
detail became popular.
Lustre appeared in Italian ceramics in 1497 where it was made at Deruta, still a
pottery centre, north of R o m e towards Florence. It is not k n o w n w h y lustre
appeared at this centre. Hobson and Burton agreed that "the earlier examples are
hardly distinguishable from Spanish ware, and to the last the ware remained
technically like earlier ware, though with perfectly Italian decorative treatment".38
^Hobson & Burton, in Cox, p. 368.
23
E u r o p e a n Tin Glaze.
In Europe tin glazing was developed, used for a period, lost popularity, and was
then rediscovered and it appears on some of the very earliest pottery. It was
probably associated with the earliest alkaline glazes and later with glazes based on
lead, and again there is no information on the events leading to it. T o m a k e a
transparent glaze for earthenware the potter needs to melt silica which is in nature
a glass former. T o get silica to melt it must be combined with a flux. In early
times alkali fluxes of soda and potash were used and some time later lead oxide
became the most c o m m o n flux. Lead oxide is one of the most vigorous of the
fluxes and makes possible excellent transparent glazes often coloured with metal
oxides of copper for green, cobalt for blue, iron for yellow and brown.
It was found that the addition of up to ten percent of tin oxide made the glaze
opaque and white and from the earliest times this 'tin' glaze was used to either
cover clay that was coarse or dark or to provide a white surface upon which to
paint. Tin has always been very expensive and therefore in Italy its early use was
to cover only a portion of the pot. It proved to be a perfect surface upon which to
paint decoration in the low fired 'enamel' colours. Later, when Chinese blue and
white porcelain was imported into Europe, the potters used the tin glaze and cobalt
in an attempt to copy it. The great pottery centre of Faenza in north east Italy was
started in the middle of the 16th Century and it gave its n a m e to decorated, tin
glazed wares which are n o w universally k n o w n as faience. A n alternate term,
majolica, is sometimes used, named after the island of Majorca. Technically the
Dutch Delftware is exactly the same although it was a deliberate attempt to
reproduce the Chinese blue and white wares. This earthenware is nothing like
Chinese porcelain other than superficially being a blue and white ware. It was not
until the early 18th Century that European porcelain was made.
A good deal of our early knowledge about the production of faience in Italy comes
from a book written by a potter, Cipriano Piccolpaso.39 In the late 15th century he
wrote exhaustively about the methods, clays, glazes, pigments, kilns and the firing
used in Italy. H e tells us the firing should not be done during the moon's wane
because the pots would then lack brightness! The pots of this period ranged
widely to include jugs, vases, platters and alberelli or apothecary jars with concave
sides. Italian tin glazed wares often combined the excessive use of colour with
decoration which was storytelling and pictorial to the point where there was little
room for appreciation of the beauty of the pot itself.
39
Cox, p. 356.
The coloured enamel tin glaze pottery spread to France and Germany where it was
continued in more or less the same style as in Italy with ornately shaped ewers and
storytelling decoration. I have written earlier that all European pottery from
R o m a n times until the discoveiy of porcelain in the 18th Century was earthenware,
that is, low fired porous ware. The exception was in Germany prior to the 16th
and early 17th centuries where true stoneware was made.
Stoneware is produced
by firing the clay to sufficient temperature to cause the clay particles to fuse or
vitrify so that the ware is so dense that it can hold water without a glaze. The
stonewares were based on clays found along the Rhine and its manufacture was
confined to a relatively small area including the towns of Hohr-Grenzhausen,
Sieburg and Cologne. The clays varied in colour from near white to dark brown
and the wares were extensively modelled upon with coats of arms, the hunt,
w o m e n and merchant's marks. The best k n o w n applied modelling is in the form
of a bearded face on the neck and shoulders of a jug. Glaze in the conventional
sense was not applied, but salt glazing was employed. W h e n the kiln reaches high
temperatures c o m m o n salt is thrown into the kiln where the heat breaks it down
into its components of sodium and chlorine. The chlorine gas exits through the
flues while the soda vapour settles on the surface of the pots (and the kiln) where it
combines with the silica in the clay to form a simple glaze. The glaze can be
thickened by repeated applications of salt. This sort of glaze can show modelled
decoration in a sympathic way where normal glazes m a y mask it. Later the pots
were decorated with cobalt oxide painting and some wares even had coloured
enamels applied. There is still an industry in Hohr-Grenzhausen though not on a
large scale. I was there in 1977 and most of the massive old kilns are no longer
fired and some have become display areas in museums. C o x 4 0 writes that the 18th
Century saw the end of handmade pottery in Europe and with it some of its human
appeal.
40
Cox, p. 418.
25
Chapter 3
INDUSTRIALISATION AND STUDIO POTTERY
In Europe in the 18th and 19th Centuries the Industrial Revolution changed the
w a y goods were produced and the w a y people lived. The invention of machines
to manufacture things that had formerly been made by hand and in small quantities
not only changed the w a y people earned a living but m a d e available to almost
everyone standardized goods of every description. Starting with the textile
industry, the spinning and weaving of wool and cotton, factories were built to
supply almost every article used by the people. M a s s production of great
quantities of what w e n o w call consumer goods meant that m a n y articles came
within the purchasing power of the average person. Large plants standardised
materials, researched methods of production and organised the division of labour,
all with the view to produce more and usually cheaper goods. This seemed to be a
wonderful thing-more products of a good standard cheap enough for all to buy.
But there was a reaction to the whole concept. Historically the goods and artifacts
needed by the community had been supplied by local craftsworkers. The carpenter
had m a d e furniture, the blacksmith fire irons, hinges and horseshoes, spinning
was a daily chore for the housewife and the weaver took the wool to produce
cloth. The potter was often a village craftsperson w h o m a d e the pots that the
villagers wanted, such as milk pans, plant pots, storage jars and chamber pots.
Potters mostly dug and prepared their o w n clay from local deposits in the manner
of potters all through history. The pots were usually of red earthenware, fired in
simple kilns capable only of attaining the temperature required for earthenware
temperatures.
It was in China and the Far East that kiln technology had reached the stage where
very high temperatures could be reached to enable stoneware and porcelain to be
made, apart from the salt glazed pots made along the Rhine in Germany, as already
noted. Outside China virtually all the pots m a d e in the world at this time were red
low-fired earthenware whether m a d e by so-called primitive peoples or by potters
in more sophisticated societies. In Europe m a n y of the potter's wares were
unglazed. If glazed at all the glaze was usually m a d e from a raw lead ore called
galena. The ore was simply ground to a powder and dusted on to the wet pot and
when heated the lead in contact with the silica in the clay became a simple glaze.
26
M o r e recent knowledge about the toxicity of lead glazes suggests that people
would have suffered lead poisoning from glazes in contact with acids such as fruit
juice and vinegar.
It has been said that Wedgwood, "created an industry and killed a craft". He led
the indusuial reorganisation of ceramics in England creating factories which used
mass production methods. The division of labour m a d e cheaper pottery of a very
high standard available to a broader public. His range of "Queens W a r e " was very
popular. Naturally other manufacturers soon followed his lead not only in
England but in other parts of Europe as well. But his very success led to criticism
of his quality and design and of the w a y that workers had become almost
machine-like parts of production with the feeling that the input of the individual
had been lost. G o n e was the almost daily contact between the maker and the user.
While the factory-made pots were of better technical quality a great number of
people missed the personal touches that had characterised the handmade wares.
For instance, the texture resulting from the hammer of the smith was missing, as
was the homely, uneven thread from the spinning wheel, the recognisable finger
marks of the village potter and the simple but appropriate decoration used by the
craftsperson. Even though factories often m a d e articles in imitation of, or at least
in the style of, the handmade the differences always showed. The anti-industrial
feeling gradually grew into what is k n o w n as the Arts and Crafts M o v e m e n t and
the best k n o w n figure in the mid to late 19th Centuiy was William Morris. H e set
out to develop well-designed goods, furniture, wallpaper, textiles and ceramics.
H e set up companies to exploit the 'well-designed' concept. H e was only partly
successful but he laid the groundwork for what was to be a continuation of an arts
and crafts concept, that there was still a place in society for artists and
craftsworkers to produce articles that were well-designed while carrying the
individuality that goes with a small workshop or a single worker. While the
number of craftworkers continued to decline, Morris's concept was not lost, for
what happened was that Arts and Craft Societies came into being and in various
ways the members endeavoured to keep alive all manner of craft activities.
Certainly until World W a r II most of the crafts were the province of the Arts and
Craft Societies and of a very few individuals w h o continued to work as
craftsworkers. In ceramics w e have c o m e to call these people Studio Potters or
Artist Potters. It is not easy to define exactly what a studio or artist potter is
because there are so m a n y potters working in different ways w h o could claim the
title. S o m e work together in groups sharing space and equipment, some actually
work almost as a small factory, and others work alone. M a n y m a k e pots in large
numbers in what m a y be called a small factory attempting to supply the ordinary
27
needs of the community, as did the mediaeval potters, making m u g s and
casseroles by the hundreds marketing through markets and craft shops, while
others set out to m a k e individual pots in small series or 'one offs' and sell through
their o w n studios and in exhibitions in galleries as painters and sculptors do. In
Australia this concept was reflected in the aims of the Crafts Board in the seventies
and eighties.
T h e Leach Contribution
Before World W a r II there were some notable individual potters in France such as
Chaplet, G a m e s , Delaherche, Decoeur and Cazin and William Burton in England.
However, it was the publication of Bernard Leach's book A Potter's Book41 in
1940 that sparked off a n e w emphasis on the individual as a potter and brought to
the attention of Western craftspeople, especially potters, the art of Japan. While
there had been m u c h contact between China and Europe over the centuries with
the large trade in Chinese porcelain, particularly the blue and white, and while
there had been periods of great interest in all things Chinese w h e n it was
fashionable to decorate homes with Chinese artefacts, the 'Chinoiserie' period,
and while the English factories had produced near copies of Chinese pots—the
famous Willow Pattern is not Chinese but English—the effect on craftsworkers
was minimal until A Potter's Book was published.
The same can be said about Japanese wares. After the middle of the nineteenth
century w h e n Japan opened up to the world following several centuries of
complete isolation Japanese artefacts and pottery were freely available in Europe
and European factories copied some Japanese styles. It is amusing to note that
some English factories copied, with or without variations, the famous Japanese
Imari Wares. S o m e of these variations were then copied by the Japanese factories
and it became a three way copying style with some of the Chinese factories doing
the same.
Leach claimed that the Song Potters produced pots that are among the best ever
made. Their range of shapes was broad, the shapes were always suited to the
function of the pot, decoration, when used, was also always suited to the pot and
the glazes used were such that it is considered that they have never been bettered.
The Celadons of Lung Ch'uan, the Kuan glazes, the Chuns and the Tz'u Chou
readily spring to mind as amongst the supreme glazes of the Song period. The
Chinese had at their disposal deposits of very suitable clays from which they
41 Leach.
28
developed stoneware and porcelain. The Song potters were making porcelain
more than a thousand years before it was developed in Europe. The Song tradition
pointed to the creation of pottery whichtteatedavailable materials in a sympathetic
w a y so that the clay and glaze were equally important to the shapes and concepts.
But perhaps more important to the emerging potters was the Japanese aesthetic that
Leach had promulgated, an aesthetic of actual living in which utility is the first
principle of beauty. It is well k n o w n that Leach leamt his potteiy in Japan and his
book was a manifestation of his belief that he was a bridge between the thinking of
the w a y of life in the East, that is in Japan, and the West and his book in m a n y
ways sets out to bridge this wide gap. O n e of Leach's contemporaries in Japan
was the famous Shoji H a m a d a and the works of H a m a d a and the other potters of
his generation strongly influenced the thinking of Australian potters as they
wrestled to fathom the Eastern wisdom, for example, of H a m a d a saying such
things as, "good pots were m a d e with ease, like a m a n walking d o w n a mountain
in a cool breeze".42 The country potteries of Japan had not been affected by the
Industrial Revolution as such, so they had continued in their o w n traditional ways
and it was m e n like H a m a d a and Kawai, one of his contemporaries, that added to
this village pottery concept their o w n individualism and they became almost the
model for the sorts of activities that some Australian potters followed.
It is difficult for Westerners to appreciate the general feeling for pots in Japan a
the w a y in which they are revered. Japanese collectors pay vast amounts of
money for the simple tea bowls and other wares associated with the tea ceremony.
Such prices are never charged or paid in our Western society. N o matter h o w
m u c h attention w e pay to the Japanese it is difficult for Westerners to appreciate
the sorts of standards they apply to the simple and often, to our minds, crude
wares associated with the tea ceremony. But the tea ceremony, in m a n y ways,
drives the Zen aesthetic.
It is fair to say that Leach's book brought to the attention of Western craftspeople
the methods and the aesthetics of the humble Japanese ceramic workers with their
sympathetic use of materials, simple decoration and attention to function. Soetsu
Yanagi said, " A beautiful artifact m a y be defined as one that reposes peacefully
where it aspires to be." 43 Leach drew a parallel between this Japanese tradition
and that of the Korean potters and especially of the Chinese Song dynasty. O f
course the Song artists did not just suddenly appear, making perfect pots. The
Song followed several thousand years of continuous development of pottery in
China. Early wares tended to use metal articles as patterns. Later pots became
42Hamada, in Clark p. 86.
43
Yanagi in Clark, p. 119.
29
further expressions of what clay should do, to show the shapes more true to the
fluid nature of clay and the methods used to attain these shapes. Chinese potters
utilized the clays available in the best possible ways. The clay k n o w n today as
China Clay or Kaolin demands high temperatures for its successful use and
Chinese potters developed kilns capable of reaching the high temperature at which
this clay fires to become stoneware and porcelain. In fact the very nature of the
clay and its sympathetic use were the essential ingredients of porcelain making.
The Chinese called this material Kaolin (from Gaolin the village where it was
originally mined and still is) which literally means "High hill". Leach drew the
attention of potters around the world to the Song tradition of the sympathetic
treatment of clay and the use of superb glazes and to the excellence of the peasant
wares of Korea and those of the Japanese village potters working in a traditional
way. The Japanese called this village pottery movement the Mingei Movement but
it included not only village potters but m a n y of the great m o d e m Japanese potters,
such as H a m a d a and Kawai.
T h e Australian Scene
After World W a r II the direction of artist or individual potters changed. Not only
had Leach's book been a great influence but there appeared a n e w generation of
people interested in careers in potteiy making unlike the hobby potters w h o had
mainly constituted the Arts and Crafts Societies. After the W a r m a n y exservicemen and w o m e n attended art schools as a part of government schemes like
the Australian C R T S - t h e C o m m o n w e a l t h Reconstructions Training Scheme.
Examples of this commitment can be found in the four potters in N e w South
Wales w h o founded the Potters' Society of Australia, perhaps the earliest of the
prestige potters' organisations in this country. A short note about each of them
followsMollie Douglas completed her diploma in Design, majoring in pottery, at East
Sydney Technical college at about the time the W a r started. She had a studio at
Turramurra where she produced pots based on the English tradition of slipware
and lead glazes. She was also a teacher.
fi
Peter Rushforth trained after the war in Melbourne where the chief instructor was
Jack Knight and the emphasis there was on the earthenware tradition. Peter
moved to Sydney to take up the position of head teacher of pottery at East Sydney
Technical College in about 1950 when he was still making earthenware pots.
30
Ivan M c M e e k i n took a completely different route from the conventional training
that was available in Ausu-alia. Pre-War he had been an art student in painting and
drawing. During his service in the Royal Australian Navy and later in the
Merchant Marines he had visited China and seen Chinese pots at first hand and
these struck a chord in him. H e wanted to find out h o w they were made and tried
to become involved in China itself. This was impossible in the post-war years
with China in its confused state after twenty-odd years of the Japanese invasion,
the political chaos of the Chang Ki Shek/Mao Tse Tung conflict and the coming to
power in 1948 of the Chinese Communist Party. Having heard of Bernard Leach
he went to England in the hope that he could train in Leach's St Ives workshop.
Leach could not accommodate him and sent him off to Michael Cardew's
workshop. Cardew was a well-known potter in the English earthenware tradition
but had begun to m a k e stoneware, influenced by Leach's Eastern ideas.
M c M e e k i n became a worker in Cardew's workshop and here he was able to
acquire the techniques of stoneware production. W h e n Cardew went off to
Nigeria to introduce stoneware to the local potters M c M e e k i n remained at
Cardew's workshop running it successfully for several years. In the early 1950s
he returned to Australia to take up the position of Potter at the famous Sturt
Workshop which had been started by Winifred West. His brief there was to set up
a pottery viable as an economic venture and also as a teaching facility. Ivan
McMeekin brought to Australia a thorough knowledge of stoneware pottery.
My own introduction to pottery was different again. Pre-War I had been a parttime student at East Sydney Technical College in painting and drawing classes and
while in England with the R A A F I managed to do quite a lot of spare time study at
the Wolverhampton College of Art and at the Brighton School of Art. I was
accepted as a full-time art student at East Sydney Technical College in 1947 in the
Painting Diploma course. At this time I had no interest in pottery and cannot recall
ever having seen a handmade pot. Pottery was not part of m y diploma course but
I was almost accidently persuaded to enrol in the night class as an extra subject.
Pottery appealed to m e at once. I was interested in the immediacy of the making
methods and the direct contact with the materials. O n e of the books recommended
was Leach's book, and Mollie Douglas was one of m y teachers. I subsequently
met Ivan M c M e e k i n when I was a pottery teacher at the Canberra Technical
College. At this time I made earthenware but while in Canberra I became friendly
with Dr Lee Angel w h o had worked by himself to produce stoneware, learning
from Leach's book. M y research shows that he was the second potter in
Australia, after Harold Hughan in Melbourne, to produce stoneware pots in what
w e n o w call the Leach-Hamada tradition and it was with him that I made m y first
stoneware pots from clay from Black Mountain, fired in Dr Angel's oil-fired kiln.
31
I was fortunate in having no previous exposure to pottery in that I was able to
readily accept the Leach philosophy. Also I began potting at a most interesting
time, directly after the war when these changes were taking place in the Australian
art scene. M y ideas were set then.
Douglas, Rushforth, McMeekin and I met regularly to discuss our directions and it
is fair to say that w e all agreed that what Leach had written appealed to us, and that
pottery that w e m a d e would follow what w e thought to be in the Song tradition of
truth to materials, truth to function and a desire to create pots of the very highest
order. M c M e e k i n was of great value in our discussions as he was the one most
versed in a practical w a y in stoneware production. Douglas, Rushforth and I,
profited greatly from his generosity in sharing his vast knowledge and w e all soon
switched to making stoneware. From these informal meetings grew the idea that
w e should formalise our ideas into an organisation and the Potters' Society was
formed. It was followed by other similar groups being formed in most states.
Later more broadly based craft groups interested in all the crafts were formed
under the general n a m e of the Craft Association of the various states.
During the next ten years a number of significant events reinforced my
commitment to the concepts of the Leach-Hamada tradition. M y first teaching
position was in Melbourne where the famous Kent Collection is in the National
Gallery of Victoria. This collection enabled m e to see for the first time Chinese
pots of all historic periods. M y visits were numerous. T o this day I remember the
glazes, the celadons, the juns, the temmokus and the clear yellows. Later in
Canberra an exhibition at the Dutch Embassy brought more pots from China to m y
attention. This collection had been m a d e in China by one of the secretaries whilst
stationed in China and again I was confronted by the simplicity and the beauty of
the pots and the magnificence of the glazes, and as it was an informal exhibition
the pots were available for actual 'hands on' study. M y regular visits to Mittagong
to talk with Ivan McMeekin brought m e into contact with his collection of not only
Chinese pots but also the works of Leach and Michael Cardew. M a n y a meal was
served on plates of one or the other. After I built m yfirstkiln at M o u n t Kembla in
1955 m y stoneware path was clear.
Other Influences
In 1962 I was able to visit Japan for the first of a number of visits. Naturally m y
aim was to see as m u c h as possible of the work of the potters I had read about.
M y centre was in Kyoto where a former Canberra student, Cecily Gibson, was
studying. She introduced m e to Fred Olsen an American potter w h o was working
32
there and w h o has since become well-known for his books on kiln construction.
Also visiting Japan at that time was Daniel Rhodes the famous potter and author of
potters' books 4 4 and an academic from Alfred University. A s it happened Fred
Olsen was living in the studio of Tomimoto w h o at that time was very ill in
hospital. Olsen was acting as caretaker and using the studio for his o w n work and
I was able to make some pots there using Japanese clays, brushes and glazes.45
The first of the great Japanese potting families whom I met was the Kawai family.
Kanjiro Kawai, about w h o m Leach had written, was already dead but his heir,
Hiroshi, was living in the house where he kindly showed us m a n y pots m a d e by
Kanjiro. Hiroshi also m a d e pots though he never became well-known. H e gave
m e a press-moulded rectangular bottle with a greenish dark glaze with poured
contrasting glaze decoration, a valuable part of m y collection. The whole of the
garden area was covered with Kanjiro pots, hundreds of them lining all the
pathways. The house is n o w the M u s e u m dedicated to the work of Kanjiro Kawai
and in it are m a n y of the pots which used to grace the garden. It seems to be
traditional in Japan for houses and workshops of famous people to become
museums in their honour. Kanjiro, while working in the traditional way of which
Leach wrote was also somewhat of an innovator. S o m e of his vases were
unusually shaped. They were made for use in the tea ceremony or for inclusion in
the special alcove called a tokonoma in the Japanese h o m e used to display a flower
or a few flowers accompanying a scroll on the wall I recall one shaped in a soft
'L form', which was unique. This impressed m e for it meant that these traditional
workers were still free to push the forms they used into new shapes.
The nephew of Kanjiro was Takeichi Kawai who carried on the fame of the Kawai
family as potters. H e lived in Kyoto and became a personal friend. H e died in
1990. In the early sixties Takeichi had a very large workshop in what is called the
Gojo area of Kyoto. The Gojo, literally meaning 5th Street, was the area where all
the potters worked, most of w h o m , Takeichi included, had the large eight chamber
noborigama climbing kilns. These werefiredwith wood about once per month by
professional firemen and held anything up to 20000 pots. Sadly these marvellous
kilns have all gone now, forced out by clean air and smoke control conditions. It
must be said that in 1962 it was easy to find a kiln firing-one just followed the
smoke in the Gojo. Takeichi Kawai was a member of the Yamato Mingei circle of
potters and followed the ideals of a humble peasant potter though he was the head
of a large and successful mini-factory. H e designed all the wares m a d e and
^Daniel Rhodes. Clay and Glazes for the Potter. Pitman, NY, 1969.
^Subsequently, I was informed that one of these pots had been acquired by Kondo Uso, the
Professor at the Bidei University, for the University collection.
33
controlled a quite large group of potters and workers. The size of this large
enterprise somewhat surprised m e . Kawai took part in m a n y phases of the work
as the need arose, but most of the wares were produced by the workforce. Kawai
was particularly well-known for his tea bowls and for a large array of pressmoulded shapes. His glazes ranged from the dark temmokus through a blue
k n o w n as ruli to a delicate celadon k n o w n in Japan as seigi. M a n y of the dark
glazes used were based on the crushed rocks from the K a m o River which flows
through Kyoto. This was of particular interest to m e for I had studied the rocks in
the lllawarra area with glaze making in mind and at about this time had been
awarded the Fellowship of the Sydney Technical College for m y thesis.46 M y
interest in these materials had been sparked off by Leach w h o had written of the
Kimaicki stone at Mashiko as a glaze material and of the K a m o River Stone at
Kyoto. Actually most of the potters there bought the rock glazes already prepared
and I was unable to determine whether it was in fact the pure crushed rock or
whether the rock was used simply as an ingredient in the glaze. The glazes used
by Kawai were quite traditional, the celadon, temmoku, a greenish tea-dust and a
clear white with applied blue brushwork.
In the workshop of Tomimoto I was able to see at first hand the results of a
transition in his case from being a humble Mingei potter to one of great skill and
sophistication. Towards the end of his life Tomimoto worked exclusively in
porcelain with very intricate decoration in cobalt blue and m a n y low-fired,
coloured enamels. The work was in some ways related to the industrial wares of
the factories such as Noritake, however it was decidedly individual and different.
Tomimoto had an industrial background which he developed in an individual way.
H e used the conventional decorative methods of the Chinese and Japanese
porcelain factories but in a n e w and refreshing way. His porcelain wares were
fired to the high temperatures required and under the glaze he applied blue
decoration of cobalt often in very simple lines. Subsequent firings at lower
temperatures added reds, greens and gold, somewhat in the manner of Nabeshima
and Imari wares, but without their copying of textile and conventional patterns. A
great deal of Chinese and Japanese highly decorated wares rely to a significant
extent not only on traditional patterns but traditional patterns that have been
reduced to pattern books as the learning tools of the pottery industries. Travelling
in China through the factories in the porcelain producing cities such as Ching te
Chen one sees these books in the so-called 'design' sections where workers copy
the patterns produced. Blossoms of various kind-plum, lotus, cherry-trees such
as pine and plum, b a m b o o in its m a n y forms, tigers, dragons and birds are
46ivan Englund.
34
reduced to a formal pattern and the design part seems to be confined to different
combinations of the motifs. This is, of course, not very different from European
practice. I a m merely making the point that T o m i m o t o did not, in his highly
decorative painting, merely copy the motifs so often used in porcelain.
35
B&fl
Tomimoto Plaque - Kyoto 1963
36
Tomimoto did at one time design a line of dinner ware for industrial production in
which the cobalt blue decoration on the pure white edge of the flat wares
contrasted with intersecting brush mark of intense red. H e also produced m a n y
circular wall plaques on which he wrote a p o e m in cobalt blue with just one
contrasting blossom in red and green enamel. Even without the translation of the
poem it was easy to appreciate the beauty of the Japanese calligraphy.
Like many of the Japanese potters, Tomimoto had no qualms about expediting his
pottery production. A s the occasion demanded he would have expert artisans
m a k e moulds from his models. H e was interested in the final work rather than in
the mundane work expended in the manufacture. This surprised m e . M a n y of
Tomimoto's pots were simple elegant shapes with a translucent white glaze
decorated with cobalt blue applied before the glaze firing and subsequently further
embellished with red enamel, often with a poem. Japanese calligraphy lends itself
to decorative effects. S o m e of the superb Japanese brushwork on T a m b a Saki
bottles so m u c h admired by Australian potters might simply be a caption reading,
"Drink Ito's Saki!" The use of the brush in calligraphy is regarded as an art form
equal to painting, sculpture and ceramics and great attention is paid to fine writing.
From Kyoto I took a day trip to the traditional pottery centre of Tamba. The whole
area is classified as a National Treasure. The kilns are similar to the big Chinese
'Dragon' kilns, a long upward-sloping tunnel without inner divisions, packed
through openings at intervals up the hill and fired initially from a firebox at the
bottom, then successively side stoked through small holes on both sides as the
temperaturerises.The wares at this T a m b a kiln site were exclusively saki bottles
and jars and plant pots all glazed with a high iron glaze, called in Japan Kaki.
S o m e had a splashed or poured glaze decoration of black. The shapes were
traditional and had not changed over m a n y centuries. The clay was a sandy
yellow, rather sticky material, not as easily thrown as the Australian clays I had
used. The light wooden Japanese potters' wheel was difficult to use at first, as I
found when invited to make a few pots at the workshop of the Ichino brothers.
From Kyoto it was convenient to visit the big pottery cities of Seto and Tajimi.
Seto produces industrial wares as well as pots and Tajimi is the centre for Shino
glazes. Shino glazes are popular in Japan, often seen in the tea ceremony ware.
The clay is sandy and porous and the glaze is white to apricot in colour. It is
usually full of pinholes and often crawls leaving gaps in the surface. The tea
bowls are decidedly asymmetric and the rims uneven. A s one travels to broaden
one's horizons there have to be some things which do not appeal. Shino to m e is a
technique that has never appealed, not even after having spent an afternoon with
37
the famous Arakawa, a Living National Treasure, w h o had produced a tea bowl
which was acclaimed as the best Shino tea bowl that had ever been made.
I next went to the Bizen area near Okayoma. Bizen is another place where the
same sorts of pots have been m a d e for hundreds of years and they are good
examples of the use of a special clay and special firing technique. A very black
clay occurs a few metres under the rice fields. It is unique to the area. It is so
highly regarded that at present no building is allowed until the clay is mined and
stockpiled. The firing is usually continuous from four to seven days. N o glaze is
applied. The long firing with w o o d deposits fly ash on the pots and w h e n the
temperature is high enough the ash melts into a crude glass coating. The different
areas in the kiln receiving different amounts of ash give differing results. S o m e
pots are even fired in the fire-box and these receive heavy lava-like ash deposits.
Further from the fire the ash becomes more like a glaze. Pots are stacked together
and on top of each other to cause variations in the flame path, giving rise to
variations in ash deposits. Small shards are also used to resist ash, resulting in
different coloured areas. In the coolest part of the kiln rice straw is draped over
the pots leaving red marks w h e n it b u m s away. This is called hidasuki. M y host
was another Living National Treasure, Kaneshige Toyo. His family, together
with the Fujiwarra family, had transformed the largely industrial use of these
techniques into an art form. Most of the wares m a d e by Kaneshige (and the
Fujiwarra's and m a n y others since) were either saki bottles, cups, or tea ceremony
ware. It is not unusual for exhibitions in Tokyo galleries to consist of perhaps one
hundred and fifty saki bottles all of the same shape, all about 1 5 0 m m high and
differing only in the w a y the ash deposits have decorated the pots. Western
potters have followed this Bizen method of making pots and in some ways it
represents a sort of Song tradition of exploiting a material and a technique to
achieve a unique product. For myself, while appreciating the style, I was more
interested in what might be called conventionally glazed pots.
Moving on to Kyushu I was able to see the Korean-based Karatsu wares which
again were consciously crude, designed for the tea ceremony. At Arita I found
porcelain wares that were almost at the opposite end of pottery making techniques
from those I had seen at Tamba, Bizen and Karatsu. The whole of the Arita area
seemed to be devoted to porcelain making. History tells us that in the 1590s, after
an unsuccessful Japanese invasion attempt on Korea, a Korean potter was brought
back and he discovered the very useful porcelain clay deposit which m a d e
possible, together with his expertise, the very important porcelain industry at
Arita. There numerous factories produce high class porcelain Imari wares. At
first these were of the 'blue and white' family, white porcelain glazes painted with
38
cobalt oxide in a wide range of patterns. Later Imari wares became more ornately
painted utilizing not only cobalt blue but reds, greens, purples and golds in the
form of low-fired enamels, m u c h after the style of the highly-decorated pots of
the same periods in China. M u c h of this pottery has been criticised as being too
highly decorated often in patterns derived from textiles and are regarded by some
as aesthetically inferior to other porcelain. More highly regarded are what are
called Nabeshima wares which, while using the same techniques, exhibit superior
standards of technical skill because they were produced not for a mass market but
solely for presentations to feudal lords. Its colours were always harmonious, the
designs were uniquely appropriate for bowls and plates and the enamels used often
resembled the delicacy of water colours. The wares were produced for only a
short period and were rarely exported. In Arita, in contrast to the many factories
there, are two families which have continued to produce very personalized
porcelain wares to the present day.
About 1660 a potter perfected Chinese enamel techniques and produced an
orange-red overglaze colour which reminded him of aripepersimmon. The name
of persimmon in Japanese is Kaki and this potter took the family n a m e of
Kakiemon. Kakiemon wares are noted for a milky white colour, with veiy careful
brush painted designs and were a direct influence on European factories at
Worcester, Delft and Meissen when European porcelain making became possible
in the early 18th centuiy. Kakiemon was aimed at the export market.
In opposition to Kakiemon was another family named Imaemon which also
specialised in the overglazing enamel technique and has continued to produce very
highly regarded ceramics. I did not visit the Imaemon workshop until about 1983
where I met Zensho, the 13th generation Imaemon, w h o had been m a d e an
Important Intangible Cultural Treasure, which w e call a National Treasure.
Eventually I went to Mashiko to meet the great Shoji Hamada. Mashiko is a
couple of hours North of Tokyo. H a m a d a had m a d e it his h o m e m a n y years
before and Leach had worked there from time to time. I telephoned H a m a d a from
Tokyo and he simply said, "come tomorrow, w e arefiringthe kiln". H e met m e at
the gate where the taxi dropped m e . H e was dressed as always in his baggy
peasant clothes. His welcome was warm. I was shown the whole complex of
pottery workshops. The H a m a d a property was large. There were three climbing
kilns, one of which was firing and he had a small salt glazed kiln which he had
built to fulfil a special order of 18000 beer mugs.
On the property were numerous large thatched farm houses. He had bought them
and had them re-erected as living units and workshops. O n e contained his vast
39
collection of pots. "I buy anything that I think I could not make", he said. The
collection contained Chinese pots from Han, T'ang, Song and Ming times. There
were pots from historic Japan, Haniwa, Jomon, Yayoi, Sue, and of course pots
by Bernard Leach. T w o large gate houses were storehouses for his o w n pots.
There were stacks and stacks of pots from his workshops and his o w n private
works. A generous man, he presented m e with one of his plates. The pots which
I remember most clearly were those strong simple shapes both thrown and pressmoulded with the fresh decoration of poured slip and glaze for which he was
famous. The surfaces of the rectangular press-moulded bottles were often divided
into square patterns of Kaki and cream glazes, upon which he usually
superimposed a calligraphic decoration based on an early drawing of his of a
sugar-cane shoot. The Kaki glaze was composed of the local building stone
crashed to a powder and called Kimaichi stone.
40
Hamada Pots-Mashiko 1963
41
A s mentioned before the Japanese word for persimmon is Kaki and the best Kaki
glazes which are coloured with a large percentage of iron oxide have an orange
colour not unlike that of aripepersimmon. This he used with great effect together
with a black temmoku. S o m e of his greens were obviously based on copper
though he used celadons too. His white glaze was a simple one which included a
large percentage ofricestraw ash.
Hamada was meticulous about his glaze materials. On one occasion while seated
at one of his low tables near a brightly burning fire—it was the middle of winter—
he told m e that wood ash was used in m a n y glazes and he kept the various ashes
separate. For example, the fireplace near which w e sat burned only a special pine
wood that was brought to him by local farmers and he washed that ash ten times
before use. The building where pots were made was one of the large farmhouses
already mentioned. It was light and aiiy. The clay was in the middle of the area,
a mass of perhaps a tonne, covered, and from which the throwers cut their
requirements. There were six or seven throwers using the light wooden Japanese
wheels turned with a stick. W a r e boards held pots on racks and outside in the
open freshly thrown bowls were placed to dry. I was moved by this scene,
exactly as described by Leach. The kiln which was firing was attended by most of
the workers. H a m a d a told m e that even on their days and time off all the workers
turned up as usual. During the day H a m a d a excused himself to meet his boxmaker from Tokyo to sign the box lids. H e did not sign his pots but only the lids
of the boxes in which they were stored and exhibited. While in Mashiko Hamada
also introduced m e to his neighbour and student Shimaoka and to another potter
working in the same Mashiko tradition, a Mr. Sakura. Sakura-san showed m e
two plates made by Bernard Leach at his pottery during one of his many visits to
Japan.
42
"I
Leach Pot-Mashiko 1963
43
This journey to Japan reinforced m y feelings about the way I was working and the
w a y I thought m y future directions lay. Seeing the Japanese artists at work
clarified m a n y of the ideas I had about what Leach had written. Reading about the
methods and aspirations of the Japanese potters was in m a n y ways different from
the reality of meeting and talking to them. I had gained the impression from A
Potter's Book41 that the great Japanese potters worked and lived like anonymous
peasants, individually turning out pots for everyday use, using whatever crude
materials were available. But this was far from the reality. All the well-known
potters I met were heads of teams of potters running large and well-organised
workshops. They were revered by all. M a n y had been honoured by that
marvellous title "Important Intangible Cultural Treasure"—equivalent I suppose to
a Cultural Knighthood.
Potters are ranked in Japan equally with the painters,
sculptors, calligraphers, weavers and musicians. There seems to be no gulf, as in
our society, between the "Arts" (painting and sculpture) and the "Crafts" (pottery,
weaving, textiles). This is the sentiment expressed by Coplans w h e n he says,
"What distinguishes a work of art from that of craft is qualitative. A work of art is
not concerned with the utilitarian, the rational and the logical. Its purpose is
expressive, it is concerned with the aesthetic experience in its purest form".48 The
prices paid for pots were equal to the prices painters get for their works. It was
rumoured while I was in Japan that a collector-a Japanese-had paid US$25,000
for the famous Shino tea bowl m a d e by Arakawa. Hamada's large plates were
available for about A$200-400. W h a t a contrast with Rushforth and Hughan, two
of Australia's best potters at the time, w h o were selling pots for two or three
Guineas, equivalent to A$4.20 and A$6.30!
Having been convinced by Leach of the legitimacy of making pots in a
straightforward way, based upon a container or vessel, and with the firm idea that
these shapes depended largely on a 'truth to materials' approach, I was able to
choose more confidently the sort of Japanese influences I favoured. H a m a d a was
the dominant figure in m y view. I appreciated his pots for their confident
simplicity, for his use of a quite limited number of, for him, appropriate glazes and
I saw in his glazing techniques of poured glazes one over another something that
appealed to m y w a y of thinking about decoration. The poured glaze technique
appears to m e to be one which is spontaneous, immediate and peculiar to the
potter's materials. The closest anything in the wider art world comes to it is the
poured and dripped paintings of Jackson Pollock. It is a technique that I have
used consistently in m y o w n pottery. With practice s o m e control is possible,
though their are some accidentals that have to be evaluated and dexterity underpins
47
48
Leach. A Potter's Book.
John Coplans, in Garth Clark. Ceramic Art. p. 153.
44
artistic merit. Unlike conventional painting, where there is the opportunity to paint
over or scratch out undesirable passages of paint, the potter gets only once chance
for the poured decoration to be right. S o m e courage is needed. So the Mashiko
wares took an important place in m y pottery thinking.
While I appreciated the effects of firing on clay occasioning subtle colour changes
and textures, and the deposition of fly ash melting to a natural glaze, and while
from time to time I experimented with the Bizen technique, m y real interest was
directed to conventional glazes. The unglazed wares of the Bizen potters,
Kaneshige and Fujiwarra, o w e everything to thefiringprocedure and the choice of
clay. Often the results are what the Japanese call shibue, a word that Leach says is
almost untranslatable but could be thought of as austere, subdued or restrained.
Etymologically it means "astringent". The word implies almost the opposite of the
unctuous, tactile beauty of the Lung Ch'uan celadon glazes of the Song period.
Some potters of my generation have in the past been accused of blindly copying
the shapes of Chinese or Japanese pots. T o refute this claim it is pertinent to
consider, for example, the pots of the Song times. Perhaps the most famous and
certainly the most published Song pot is a vase of a shape called Kinuta. "Kinuta"
means "mallet". The Song Kinuta pot has a shape relating to the mallet used by
w o o d and stone carvers. The shape is m a d e of several sections luted together,
basically a cylindrical shape in the main body surmounted by another cylindrical
shape above of smaller diameter-the handle of the mallet. This "handle" shape
ends in a wide flaring mouth. T w o handles are attached and these are described as
"bird neck and head handles". M a n y Chinese wares have handles of animal
shapes, such as elephants and dragons and this sometimes extends to the knobs on
the lids of covered jars. I do not see m u c h evidence of this type of design flooding
the studios of Western potters. The glaze is the celadon which has been admired
for a thousand years m a d e from feldspar and coloured by the small amount of iron
oxide inherent in the glaze materials as impurities. This iron oxide in the glaze,
fired in an oxidizing kiln, will result in various degrees of amber depending on the
amount of iron but if fired in a reduced atmosphere the iron oxide is changed so
that the colour is green. T h e Chinese kilns which were fired with w o o d
demanded great skill in operation but the Song potters, backed by literally
thousands of years of tradition, were masters of the art. The colour of the celadon
most admired is one that tends to be blue-green, although celadon can be of a
number of different greens. C o x quotes a Chinese reference to the colour as "egg
white", noting that in China ducks eggs are always pale blue or pale green, and
further says the colour should be "blue like the sky after rain"49. The Lung
49
Cox, p. 197.
45
Ch'uan celadons are noted not only for their colour but also for their texture. The
old Chinese critics wrote in terms of "rich and unctuous, lustrous or fine and
glossy". Later Ming writers used descriptions of the texture as "transparent and
thick like massed lard". Surely something is lost in the translation.
Another shape much used by the Chinese and which has not been favoured by
Westerners is the incense burner. This is usually a deep, three-legged bowl with
elephant head handles. If a pot was provided with a cover (even vases sometimes
had lids) it was often decorated with realistic Chinese lions. A vase with a long
neck could have a stalking tiger modelled around it and one early Lung Ch'uan
vase had a dragon, chicken and reclining figure modelled around the shoulder. It
is only in recent years that I have noted the use of such modelled figures on
Australian pots, the favourite animal being the frill-necked lizard, and of course
one remembers in the middle of this century the ubiquitous Koala ornaments,
mostly in painted plaster, which almostrivalledthe famous flying ducks seen on
m a n y walls. The wares from the Lung Ch'uan kilns were destined for the
Emperor's Court, so pots sometimes had additions that were an adjunct to the
luxurious surroundings. For example, large wine jars with small tubular additions
on the shoulders in which flowers could be placed were m a d e in great numbers.
Of course there are many Chinese pot shapes which could be described as
universal and directly related to the forming action of the material on a potter's
wheel and these are the ones used by Western potters. The shapes which form
naturally on a potter's wheel are composed of cylinders with outward and inward
curves and the combinations of these are almost limitless. The old Chinese pots
include those with long necks and those with short, globular and spherical vases,
all of which constitute the normal range of shapes m a d e by potters everywhere
whether they have seen Chinese pots or not.
The main thrust of influence of Eastern pots on potters in Australia in the
immediate post-war period of the forties and fifties c a m e from Leach and his
English followers. The Leach book 5 0 began the Australian interest in English
pottery and the contact with Leach, Cardew and Harry Davis was personal because
of their visits to Australia. These potters visited Australia usually to conduct
workshops, give demonstrations and have exhibitions. The influences from Asia
and the robustness of English country pottery w a s added, sometimes with
amusing manifestations. For example, m a n y Australian potters produced cider
jars!-surely a misdirected effort if the aim was to m a k e utilitarian wares as
Australia can hardly be compared with Somerset. It should be noted that all these
^Leach. A Potter's Book.
46
influences were important for it enabled potters to sort out for themselves the
directions their work would take. Absorbing these influences and working
through them while refining skills enabled Australian potters to b e c o m e
independent as their o w n styles evolved. This is not to infer that there is a single
Australian style as yet and it might be argued that there is little need for it on the
grounds that pottery making is a universal art activity. In any case I maintain that
because of Australia's short history (in the European occupation sense), and the
period in which English settlement took place there is no Australian tradition of
pottery. The late 18th Century, w h e n the First Fleet arrived, had seen theriseof
industrial pottery in England which led to the demise of m u c h village and local
pottery. In Australia several potteries were set up in the 19th Centuiy in various
centres but they were mainly of the factory type which produced wares of the
debased industrial ranges similar to those of England. This was understandable as
our early settlers were in no w a y Australians. They were simply transferred
British. Also, because Australia was in pioneer m o d e there was little time for most
people to indulge in art or craft activities. It was probably from about the 1880s
through to the time of Federation that there was the feeling that the people in
Australia were 'Australians'. It was only in 1942/43 that thefirstreal break in our
colonial past c a m e w h e n Australians realised that they were in fact a nation
separate from England, although this realisation was not enough for us to stand on
our o w n feet and there was a transferance of our dependence to the U S A .
Peter Timms, the Australian writer, has argued that perhaps the start of Australian
studio or artist pottery could be traced to the hand-painted porcelain in the late 19th
Century. 51
A s these were factory produced pots decorated by hand I would
dispute this assertion. A true studio or artist pot would need to have been m a d e as
well as painted by the artist.
My early pots were fired only to earthenware temperatures simply because the
kilns available to m e (and others) were electric-fired, capable only of reaching low
temperatures. However, true to the materials approach, I dug and prepared m y
o w n terracotta clay and while working in Wollongong I perfected a successful
amber glaze utilizing the latite rock of the Berkeley flow which outcropped near
m y h o m e at M t Kembla.
Having settled more or less permanently in the
Wollongong area after moving around in teaching positions I was at last able to
build an oil-fired kiln capable of achieving the high temperatures required for
making stoneware pots. Again m y interest in materials dominated m y pottery
thinking and I m a d e an in-depth study of the local igneous rocks for their value as
glaze materials. Over a number of years I studied the geology of N e w South
51
Peter Timms. Australian Pottery 1900-1950. Shepparton Arts Centre, Shepparton, 1978.
47
Wales where there are m a n y lava flows and dykes, the results of ancient volcanic
action. In several cases quarries were still in production so thatfinematerial was
obtainable as crusher dust making testing very simple. The dykes were not so
easily located but I was able find most of those that I considered worth pursuing
after researching the N S W Mines Department book by Harper, The Geology of the
Southern Coalfields of NSW.52
Apart from the basalts and latites there exists in the Illawara area a sill nepheline
syenite and a deposit of tinguite, both of which are prized because their
compositions m a k e possible m u c h paler glazes than those of the high iron rocks.
M y work included the identifying and collection of samples and reducing them to
fine powder suitable for glaze testing. The glazes were calculated using the Seger
Formula and fired to stoneware temperature. This work resulted in a thesis
entitled The
Application of the Igneous Rocks of the lllawarra Region to
Stoneware Glazes in Studio Pottery. 53 For this I was awarded the "Fellowship of
the Sydney Technical College" (FSTC) in 1962. A s mentioned above I had made
a successful earthenware glaze from the Berkeley Latite and later w h e n m y
attention turned to 'middlefire'processes I made rock glazes in that firing range as
well. Apart Iron the rock glazes m y pursuit of stoneware led m e to develop for m y
use the traditional glazes of the Chinese and Japanese potters. M a n y of these were
the dark glazes coloured with large amounts of iron oxide such as the temmokus,
the kakis and the tesshas of the Japanese. I also spent m u c h time in the study of
celadon glazes, a time-consuming pursuit into a very broadfield.The only person
in Australia w h o was an authority on these at the time was Ivan M c M e e k i n because
he had inherited first-hand knowledge from Cardew and indirectly from Leach.
M y various trips to Japan, the Phillipines, Thailand and H o n g K o n g enabled m e to
see live examples of celadons of various types so that I became aware of their
beauty and the technical problems involved in their making. I m a d e m y version of
'blue and white' and for years have aimed at the elusive flambe- and copper red
glazes. I had a brief time firing salt glazes using m y o w n kilns and also having
wares fired in industrial brick and drain pipe kilns. H o w e v e r m y sustaining
interest was in conventionally glazed pots.
52
LF Harper. Geology and the Mineral Resources of the Southern Coalfields of NSW.
Ivan Englund. The Application of the Igneous Rocks of the lllawarra Region to Stoneware
Glazes in Studio Pottery. 1962.
53
48
Chapter 4
THE MIDDLE FIRE GLAZES.
In the early sixties I set myself the problem of improving the quality of the pots
being m a d e by m y students at the Wollongong Technical College. The only
prepared clays available at that time were a terracotta from Chullora in Sydney and
an industrial white earthenware. The glazes used were exclusively based on raw
lead fluxes, which while technically useful, resulted in rather harsh colours. Fired
at the earthenware temperature of about 1060°C the glazes were extremely shiny
and this was at a time w h e n the undecorated matt glazes from Sweden were
making their impact on the Australian market. Making stoneware was not possible
because the College kiln was not capable of firing to the required temperature. The
fired earthenware was also very brittle, resulting in wares that were not very
functional because they chipped and broke easily. I had decided that the pots
would be stronger and more chip-resistant if the clay w a s fired to a higher
temperature. This higher temperature I decided, after s o m e tests in m y o w n
stoneware kiln, should be about 1150 to 1160°C. A test firing in the old College
kiln proved that, with encouragement, it could reach that temperature. I then set
out to evolve suitable glazes for that temperature.
As stated earlier there is a large body of information about earthenware because for
centuries it constituted most of the production of both individual potters and
industrial factories in the West. Even in China in T'ang times a great deal of ware
fired to earthenware temperatures was produced, including the well-known T'ang
horses and camels glazed with amber and green lead glazes. The English country
pottery, the Faience of France, the Majolica of Spain, and later of Italy and the
Delft of Holland were all earthenware pots.
At the lower end of the firing range there existed a substantial interest in glazes
fired at temperatures m u c h lower than the conventional earthenware. This area is
generally k n o w n as "Raku". Its inspiration was the low-fired tea bowls of the
famous Raku family which still functions in Kyoto. The so-called raku wares of
the East are fired at temperatures of 1000°C and often m u c h less, and here too
there is a great deal of information.
49
In the area of high-fired wares, stoneware and porcelain, the information is
voluminous, especially in the years since Leach's book led to a stoneware
revolution in the West. N o w there are dozens of books dealing with the subject
and ceramics magazines publish articles of all kinds together with recipes by the
hundreds if not the thousands. Every potter has his or her o w n 'secret' recipes
which is amusing when one thinks of the thousands published. A good deal of the
mystery of glazes lies not only in the recipe but also in the firing. In the words of
Delaherche, "What miracles these twelve hundred degrees of heat can perform".54
In what I call the 'middle fire' area, the temperature range between 1100°C, the
upper limit of earthenware and 1200°C, the beginning of stoneware, there is less
information. Therefore, for the past thirty-five years I have worked in this firing
range, culminating in this current research. I dubbed m y early work on these
glazes "middle fire" to attempt to give it a status of its own. Potters used to use
terms like "high fired earthenware", which is acceptable but not the most useful
descriptor, especially if used to conveniently describe earthenwarefiredabove the
usual temperature, often because a kiln had been overfired. Another term was
"vitrified earthenware". This w a s a nonsense term because by definition
earthenware is not vitrified. The definition states that earthenware typically has a
porous body. Similarly stoneware potters sometimes called their underfired wares
" L o w Fired Stoneware" but stoneware by definition has to have a vitrified clay
body.
The other major focus of my work across my career, and therefore in this
reasearch, has been to concentrate on raw-glazing and a once firing procedure. It
should be noted that the majority of pottery produced world-wide is once-fired if
w e include all unglazed wares such as plant pots, tiles, industrial items like
sanitary fittings and s o m e factory wares that are spray glazed w h e n completely
dry. A d d to this list salt glazing in which the pots are glazed by fumes caused by
the introduction of salt into the kiln at high temperatures. M a n y of the once firing
techniques in the low temperature range favoured by s o m e potters include raku
ware, primitive firing in a bonfire, saw dust firing in a container of sawdust and
pit firing where the pots are placed in a hole in the ground, covered with sawdust
and timber which is ignited and left to bum.
In contrast, probably most of the ceramics produced by artist potters and studio
potters are fired twice. The first firing called the biscuit firing (or sometimes the
bisque) to about 900° or 1000°C is for the puipose of transforming the clay into a
hard easily handled material. The pots are then glazed and fired a second time to
54August Delaherche, in Clark, p. 53.
50
temperatures suitable to mature the glazes. Because all m y work over a period of
more than forty years has been produced by once firing I decided to follow this
method in m y research into the "middle fire" temperature range. A comparatively
small number of potters sufficiently appreciate the advantages of once firing to use
it as their standard procedure. These advantages include the obvious saving in fuel
costs by eliminating a complete firing, a considerable time saving because the
setting, firing and unloading of biscuit kilns are not needed, and there is what I call
an artistic continuance of thought in that the pots are designed, made, glazed and
decorated in sequence without interruption. The ecological reasons for using less
fuel are obvious with respect to greenhouse gases.
It is possible that the once fire method could slow the working pace of a
production potter as pots have to be glazed as soon as they are ready but I would
imagine that this would be compensated for by the time savings mentioned above.
R a w glazing in the teaching situation m a y be unsuitable for students attending only
once per week, with difficulties in arranging for the pots to be in the right
condition at the right time without big storage areas but in colleges and universities
where students attend full-time there should be no difficulty.
The technical problems inherent in raw glazing can be minimised. Application is
no more difficult than using slips. The glaze is applied w h e n the pot has reached
its final shape following throwing or building and is still d a m p at the stage potters
call 'leather hard'. If the clay is too dry it m a y crack w h e n glazed and if it is too
wet the handles m a y fall off. It is simply a matter of practice. I have used a great
variety of clays over the years and have had no major difficulties with any of them.
The glaze can be applied in any of the usual ways by dipping, pouring, spraying
or brushing. Whichever method is used, the application should be m u c h thicker
than on bisqued ware, because the glaze is applied to a non-porous, leather hard
clay and there is no absorption to assist in building up the glaze layer. Small pots
can be successfully coated by pouring and dipping but there should be an interval
between first pouring the inside and then dipping the outside. If too m u c h water
enters the clay body the pot m a y collapse and/or appendages m a y sag or fall off.
Again because the ware is still in the damp, raw condition there is a limit to the size
of pot that can be dipped. With symmetrical shapes the glaze can be applied with a
brash while the pot revolves on the potters' wheel as in slip application. With
very large pots or those of very complicated shape the glaze can be painted on in a
number of layers, with a short time between applications. Because the ware is not
porous as in biscuit wares brushing is very simple.
51
The glaze is different from the biscuit type in a physical sense in that it must
contain various amounts of high shrinkage, sticky materials to adhere it to the raw
pot. Bentonite is a clay material with extreme plasticity which allows the glaze to
not only adhere to the d a m p pot but also to shrink with it as it dries. Without the
bentonite component ordinary glazes applied to a d a m p pot will not adhere but
simply flake off during diying. In other respects the chemical composition of the
glaze is almost exactly the same as for the ordinary biscuit type glaze and there is
no difference in appearances w h e n fired.
The glaze materials are weighed out in the usual way and then thoroughly mixed in
the dry state. This disperses the bentonite through the other materials. If water is
poured on to bentonite it tends to m a k e it into a gluey mass. The diy mixing helps
prevent this. It is important not to add too m u c h water. With ordinary glazes if
too m u c h water is added the excess will c o m e to the top after standing and can be
poured off but with bentonite glazes the glaze materials always stay in suspension
and there is never any water on the top to be poured off. Therefore water should
be added sparingly. For 1 kg dry glaze about 750 to 800 mis of water will be
required. It is best to add about 700 mis of water initially, stir thoroughly and then
top up with small quantities until the glaze is of the consistency of thin cream. I
use a paint stirring attachment in an electric drill and I have found it to be the most
efficient tool in a studio situation. I seldom sieve the glazes as all the materials are
finely ground when purchased and so the glaze can be used immediately. After
standing for s o m e time the glaze will appear to be very thick. This is because
bentonite is a thixotropic material that causes the glaze to become jellified. It will
become fluid again with stirring.
Bentonite and Once-fired Glazes
The calculations involving the use of bentonite as a glaze material need some
explanation. S o m e materials are simple in that they supply only one oxide to the
glaze. For example, whiting which is calcium carbonate, C a C 0 3 , loses the carbon
dioxide in the fire so that only the calcium oxide, C a O , takes part in the
calculations and the glaze composition. Bentonite is more complicated. It is a
clay-like mineral formed from volcanic ash and is reputed to be the most plastic
natural material.
There are many bentonites each differing in chemical composition. For many
years I used Western Australian Bentonite in m y stoneware glazes as did m a n y of
m y contemporaries. However this material is no longer commercially available,
probably through lack of demand. M a n y potters use imported American bentonite
52
from W y o m i n g but I decided to use an Australian bentonite mined at Wingen in
N e w South Wales, supplied by Commercial Minerals Ltd. They have various
grades, mine being dubbed PV53. The switch to this bentonite meant that I had to
recalculate the formulations for all m y stoneware glazes. S o m e alterations were
dramatic. However it is a perfectly acceptable material and I have used it in m y
once-fired glazes in stoneware, in the earthenware glazes developed for the
Montoro C o m p a n y for use on their original roofing tiles and n o w in m y research
into the 1100°-1200°C glazes.55
In the simplest terms glazes are very like glass. In nature several materials are
classed as "glass formers" the most c o m m o n of which is silica. Glass formers as
the n a m e suggests are materials that would form a glass w h e n melted alone at a
certain temperature. If silica is subjected to a sufficiently high temperature it does
melt to a glass and it is used in this form in m a n y ways. But for potters it is not
m u c h use because pure silica begins to melt at about 1713°C far too high for
general pottery making and beyond the capacity of most pottery kilns. T o m a k e
glass or glaze at a suitable temperature it is necessaiy to add to the silica materials
k n o w n as fluxes which combine with it to produce melting at lower temperatures.
The list of fluxes used in pottery includes Lime (CaO), Magnesia ( M g O ) , Potash
( K 2 O ) , Soda (Na20), Barium Oxide(BaO), Zinc Oxide(ZnO), Lithia (Li20)
Strontium (SrO). Lead oxide (PbO) used in earthenware is not used in high fired
wares as it volatilises. In any case most potters have eliminated lead entirely from
their work for health and safety reasons.
The main differences between glass and glaze is that glazes usually incorporate a
proportion of alumina, AI2O3, in the composition as this helps to control the flow
of the melted glaze. With glass makers this is not a problem because their articles
are formed of the molten material and then left to harden when cooled.
The glaze maker has to solve a number of practical problems even before
considering the aesthetics. The glaze must melt at the required temperature. It
should not flow so m u c h that it runs off the pot. It ought not to craze and it should
be a good base for colour additions.
The melting depends upon a number of factors. The proportion of fluxes to
alumina and alumina to silica are the important ones. Here the work of the German
chemist Herman Seger should be mentioned. Historically glazes had simply been
mixtures of ingredients which were found to work probably by trial and error
55
Note - Since this work has been completed I have been advised by Commercial Mineral
that Bentonite PV 53 is no longer available but but they recommend two similar materials which
are numbered Bentonites PI and CL 300.
53
methods over hundreds and thousands of years. T h e recipes were closely guarded
secrets but Seger noted that sometimes glazes used in different parts of the country
while having different recipes were very similar w h e n melted. For example one
pottery might have a glaze m a d e of whiting, ash and their local clay while another
whose glaze w a s similar might use burnt oyster shells, beach sand, and local but
different clay. Seger set out to try to find a w a y to compare the glaze ingredients.
H e decided to reduce the glaze ingredients to the oxides in an analysis and he then
evolved a formula by which the oxides in one glaze could be compared to those in
another. In this w a y it w a s possible to discover that a glaze used in one pottery
using certain materials w a s in fact similar to the glaze used in a second pottery
though the ingredients were quite different. The Seger Formula which resulted
has been used widely ever since because it makes possible not only comparisons
of glazes but an easy and reliable w a y to calculate unique personal glazes including
those utilizing local igneous rocks.
The essentials of glazes are silica to form a glass, alumina to control the flow and
fluxes to assist in the melting process. It is the control of these three materials that
enables potters to formulate glazes that will melt at various temperatures
54
Chapter 5
WORKING THE SEGER FORMULA
The range of available computer software programs for calculations in glaze
technology has grown in recent years and is well-documented in the literature.
For example, in the American Journal Ceramics Monthly articles by Harold J
McWhinnie from the University of Maryland are prefaced by a statement about his
use of a software program to build his databank of glazes. H e refers to
calculations done in this w a y pre-1983 although he does not mention a specific
program 5 6 . Pottery in Australia has also printed articles demonstrating
spreadsheet calculations for glazes.57 Australian ceramicists use software such as
Insight and Hyperglaze.
program
58
I have experimented with a Macintosh
HyperCard
for some of m y calculations and I have also included an example using
an I B M Multiplan Spreadsheet.59 However, as I do not have m y o w n computer I
have used an electronic calculator to formulate the bulk of m y glazes.
Before demonstrating the method of calculating complex materials such as
bentonite into glaze recipes it is as well to illustrate by a simple example the steps
needed to transform a Seger Formula into a glaze recipe. I will use the widely
published Calcium-Alumina-Silica eutectic which melts at Cone 4(1160°C). A
eutectic is a mixture whose constituents are in such proportions that it melts and
solidifies at a single temperature that is lower than the melting point of the
constituents or any other mixture.
The Seger formula is set out in a three column pattern and for this combination is
as follows:
1 CaO .35 A1203 2.48 Si02.
The fluxes are listed in the first column, the intermediates in the second and the
acids or silica in the third. The usual convention in Seger calculations is to work
to two decimal places.
56
Harold J McWhinnie, in C M Nov 82, Dec 83, Sept 84, Dec 91, Feb 93 and April 91.
^Pottery In Australia. Vol
58
Macintosh HyperCard developed by Daniel Midwinter Hampton
^Spreadsheet developed by Denis Chapman.
55
The prefixed numbers to die chemical compounds are molecular parts or molecular
proportions. This formula converts to the following recipe:
Material % Weight
Whiting
33.7
Kaolin
30.4
Silica
35.9
When using the Seger formula the flux column always has to add to one whole
number or unity no matter h o w m a n y oxides it includes. With the fluxes at unity
the amounts of alumina in the intermediates column and the silica in the third
column can be varied according to the temperature required for the glaze.
Sample Calculation to Transform a Seger Formula into a Glaze
Cone 4 Eutectic Glaze
A table is set up as follows:
Step 1
Formula Required
Materials
1.0 C a O
.35 AhCh
2.48 SiO?
The workings should always be set out systematically as above to minimise errors
in the calculation.
Taking the oxides in the 'Formula Required' column in order it will be found that
1.0 C a O or calcium oxide is needed. Calcium oxide is not normally found in the
studio in that form so a material containing this oxide is needed. The usual
material supplying calcium oxide is whiting which is calcium carbonate or
C a C 0 3 . 6 ° The thermal decomposition of the whiting produces calcium oxide
which enters the glaze while the carbon dioxide exits via the flue during firing.
Whiting will supply C a O in the glaze. The formula requires 1.0 C a O so whiting
is entered into the materials column with the required amount (1.0) next to it. The
1.0 is transferred across under the C a O column and subtracted resulting in zero
which means that the 1.0 whiting will supply all the C a O required.
6
^The convention with Seger formulae is to denote oxides in the form in which diey enter
fusion.
56
57
The table will look like this:
Formula Required
Materials
Whiting
1.0 CaO
1.00
35 AWQ 3
2.48 SiOo
1.00
.00
Step 2
Next the alumina or AI2O3 is calculated. It is usual to use clay to supply the
alumina. The accepted formula for clay is: 1 AI2O3 2 Si02 2 H2O
The water boils off in the kiln. The formula requires .35 AI2O3 and as kaolin is
the usual supplier, in m y glazes, kaolin is entered in the materials column,
transferred over to the AI2O3 column and subtracted again resulting in zero. So
the .35 moles of kaolin fulfills the alumina requirement. But because clay also has
twice as much silica in its formula .35 will not only give that amount of alumina
but also twice that amount of silica which is .70. This is transferred to the silica
column and subtracted leaving 1.78 more silica needed. Kaolin is the usual form
to use in glazes because its purity allows the formation of white or clear
transparent glazes but if that is not a consideration any clay can be used.
The table now looks like this:
Formula Required
Materials
Whiting
1.00
Kaolin
.35
1.0 CaO
LOO
.00
.35 AbOi
2.48 SiO
35
M
.00
1.78
Step 3
1.78 more Si02 is n o w required. Si02 is supplied by as silica, flint or quartz and
it supplies only the one oxide. So 1.78 is entered in the materials column as silica,
the amount is transferred across under the Si02 column and subtracted resulting in
zero. The complete table n o w looks like this;
Formula Required
1.0 CaO
Materials
Whiting
1.00
.35 AbOi
2.48 Si09
1.00
.00
Kaolin
Silica
.35
1.78
,35
JO
.00
1.78
1.78
.00
The table indicates that the oxides required will be supplied by the materials in that
column. The next step is to transform the numbers against the materials into a
form that can be weighed up as a recipe.
59
Step 4
To do this each material is multiplied by its molecular weight to calculate a recipe
format.
Weight Ratio
%
Whiting
1.00
x 100
100.00
33.7
Kaolin
.35
x 258
90.3
30.4
Silica
1.78
106.8
35.9
297.1
100
x
60
The Molecular weights are found in glaze chemistry reference books. S o m e
works leave the recipe as it appears in the weight ratio column but it is more
convenient to calculate it as a percentage for easier comparisons of glazes and it is
also simpler when making colour additions. The recipe is n o w shown as parts by
weight.
60
Chapter 6
BENTONITE AND ONCE-FIRED GLAZES.
T o use the Seger Formula method to calculate a glaze recipe it is necessary to
k n o w the chemical analysis of the materials used. For calculation with the
conventional and much used materials it is often assumed for convenience that they
are in fact pure and so the figures allotted to them m a y be slightly different from
actual composition. For instance, in the above example the whiting is assumed to
be pure but it m a y actually contain only 9 9 % C a O and this figure would also mean
adjustment to its usual molecular weight of 100. But the difference between the
pure and the actual is so small that in normal practice the difference is ignored.
Whiting is usually 9 9 % pure, and kaolin has a similar purity. T h e assumed
molecular ratio of kaolin is 1 AI2O3 2 Si02 2 H 2 O but that would apply to very
few kaolins for most clays have in their make up small amounts of 'impurities' and
the relationship of alumina to silica is rarely 1 to 2 exactly. For absolute accuracy
the exact analysis of the clay would be needed but in practice- the assumed and
regularly used formula for clay is adequate. This also applies to most of the other
main glaze materials such as the feldspars and nepheline syenite. S o m e pottery
books list their recipes without nominating specific materials (eg Leach).
However the two variable materials, kaolin and feldspar, that I use do in fact
conform closely to their accepted assumed compositions so I use them as is in m y
calculations. Others m a y vary significantly and such variations need to be
accounted for in Seger formula calculations, as shown below for bentonite. The
kaolin is mined at H o m e Rule in N e w South Wales and was marketed by a
company called Austral Rock Milling. The analysis supplied was:
Kaolin
Si02
46.41
AI2O3
36.49
MgO/CaO
1.03
K20
.32
Na20
1.18
Fe203
1.18
61
Ignoring the tiny amounts of fluxes which are not large enough to be significant in
the calculations, the formula is:
A1203 1 Si02 2.16
The given ratio of 1:2.16 is so close to the theoretically relationship that the
difference can be ignored.
Austral Rock Milling also supplied the Broken Hill feldspar which I use. Its
analysis is:
Feldspar
Si02
66.31
AI2O3
19.03
Fe203
.20
MgO
.50
CaO
.70
Na 2 0
1.13
K20
10.71
The formula is:
MgO .063
CaO .069
A1 2 0 3 .989
Si02 5.847
Na20 .265
K20 .603
Most potash feldspars contain a proportion of sodium but these are us
combined so the fluxes column could read MgO/CaO .132, Na20/K20 .868
totaling 1.00. The relationship between the A1 2 0 3 .989 and the Si02 5.847 is
5.912 which is very close to the assumed 1:6. The use of the commonly assumed
molecular ratio for feldspar (1:1:6) is justified because the difference from the B H
feldspar is minute.
T h e other materials pose no problems with regard to
variations in analysis.61
When using an untested new material it is necessary to have the analysis and from
this calculate its Seger formula and its molecular weight. Bentonite is a case in
61 Austral Rock Milling was absorbed by other companies many years ago but as I have alw
obtained m y materials in large quantities I still have supplies of the above materials.
62
point. In fact, bentonite is a material which varies greatly in composition from
area to area and supplier to supplier and in m y experience it is unsatisfactory to use
a 'typical' figure because I do not believe that there is a typical bentonite available.
As mentioned earlier m y switch from Western Australian bentonite to the material
from Wingen, N e w South Wales (PV53) necessitated complete recalculation of m y
stoneware glazes.
Not only are the analyses of these two bentonites different but they are phy
different as well. The Wingen material is not as sticky nor does it shrink quite so
much as that from Western Australia so more has to be incorporated into a glaze
for satisfactory adhesion to the pot. Whereas 1 3 % Western Australian bentonite in
the recipe was satisfactory I have found that about 1 8 % to 2 5 % Wingen (PV53) is
needed for the same adhesion. This is not a drawback. It is just an illustration of
the need to know the materials.
Sample Calculation of the Seger Formula for P V 5 3 Bentonite
Step 1
Divide each oxide in the analysis by its molecular weight:
PV53
Mol/wt
Analysis
60
.992
-
102
.206
6.5
-
160
.041
CaO
1.0
-
56
.018
MgO
1.8
-
40
.045
Na20
1.2
-
62
.019
H2O
8.3
-
18
.461
Si02
59.5
AI2O3
21.0
Fe203
_
63
Step 2
Arrange the results into the Seger Formula pattern which lists the fluxes in the first
column, the intermediates in the second column and the silica in the third. In the
fourth column the water is listed but as it takes no part in the actual glaze it is
ignored here but has to be included in the calculations for the formula weight.
.018 CaO
.045 M g O
.206 AI2O3 .992 Si02 .416 H 2 O
.019 N a 2 0
.041 Fe203
Step 3
In order to normalise the weight analysis to a value of one molecular unit of
fluxes the Seger formula for a glaze demands that all the figures above
have to be divided by the sum of the figures for the fluxes in the first column.
Because bentonite is a clay material the "clay convention" is applied, as described
by Michael Cardew in his Pioneer Pottery.62 It denotes that for purposes of
calculation the alumina in thefinalSeger formula must appear as "one" or unity, so
all thefiguresabove are divided by the molecular parts of the AI2O3 (.206).
Seger Formula of PV53
.087 CaO
.218 MgO 1.000 AI2O3 4.816 Si02
.092 Na20 .199 Fe203
62
Michael Cardew. Pioneer Pottery, Longman, London, 1969.
64
Step 4
To find the formula weight of PV53 multiply each oxide by its molecular weight
and add.
.087
CaO
X
56
=
4.872
.218
MgO
X
40
=
8.720
.092
Na20
X
62
=
5.704
1.000
AI2O3
X
102
=
102.000
.199
Fe203
X
260
=
31.840
4.816
Si02
X
60
=
288.960
2.238
H2O
X
18
=
40.204
483.574
round up to 484
Sample Calculation of a Glaze Recipe Incorporating P V 5 3
Bentonite.
Parmelee's63 published formula for a "bright glaze" at cone 4 is used as an
example of incorporating the P V 5 3 bentonite in the glaze calculations. T h e
bentonite is used in a once-fire glaze to cause the glaze to adhere to the d a m p pot
and oxides in it have to enter into the calculations. A s already mentioned about
1 8 % of bentonite is needed in a glaze for the proper adhesion so the bentonite is
the first material to be calculated. Previous
tests
have shown that this
equates to . 13 molecular parts of P V 5 3 in the materials column.
63
Cullen W Parmelee. Ceramic Glazes. Chicago Industrial Publishing, Chicago 1951.
65
Step 1
P V 5 3 bentonite is entered in the materials column followed by the
multiplier figure .13.
Step 2 Each oxide in the Seger formula of PV53 is multiplied by .13 and the
result entered in the appropriate oxide column. This number is then subtracted
from the amount shown in the 'Formula Required' line. The remainders then
indicate h o w m u c h (if any) of that oxide is still required and which will be
supplied by other materials.
Step 3 .23 K20 is needed.next and this will be supplied by potash feldspar.
Feldspar is entered into the materials column together with the figures .23. The
.23 K 2 0 is supplied by the .23 of feldspar so the .23 is entered under the K 2 0
column and subtracted. The result is zero and this indicates that all the K 2 0
requirement is satisfied. However feldspar also contains A 1 2 0 3 at the same rate as
K 2 0 so .23 must be entered in the A 1 2 0 3 column and subtracted leaving .07 still to
be found. In addition feldspar has in its composition six times as m u c h Si02 as
K 2 O a n d A 1 2 0 3 so the figure to be transferred to the S i 0 2 column is 6 times .23
which is 1.38. After subtraction .89 of S i 0 2 is still needed.
Step 4 Dolomite is next in the materials column with .03 as the multiplier figure.
Dolomite contributes equal amounts of M g O and C a O so it supplies all the M g O
required .03 and also .03 of the C a O . The subtraction in the C a O column shows
that .31 is still required.
Step 5 Whiting is the usual material to supply CaO so it is entered into the
materials column with the .31 still needed. This number is transferred to the C a O
column and subtracted. The zero indicates that the C a O requirement is satisfied.
Step 6 Zinc oxide is next entered into the materials column together with the .21
needed. The .21 is subtracted and the resultant zero means that no more is needed.
Step 7 Barium carbonate is entered in the materials column with .15. This is
subtracted from the amount required and again the zero shows that no more B a O is
needed. It should be noted that barium carbonate is a poison and should be
handled with great care.
Step 8 .07 A1203 is still needed and kaolin is the material to supply it. It is
entered in the materials column with the .07, the subtraction m a d e resulting in
zero. Kaolin contains twice the amount of S i 0 2 as it does A 1 2 0 3 so .14 is
subtracted from the Si02 column leaving .75 still to be found.
66
Step 9 Silica, quartz or flint is entered into the materials column to supply S i 0 2
together with the .75 needed. After subtraction the zero result shows that all the
S i 0 2 requirement has been satisfied. A check across the table will show that all
the oxide requirements have n o w been satisfied.
Step 10 It is necessary to transform the figures and materials in the materials
column into a form uhat will enable them to become a recipe. List all the materials
and their molecular ratios in a column.
Step 11 Multiply each material figure by its molecular weight. Molecular
weights are found in m a n y ceramics texts.
Step 12 The resultant figures now constitute a weight ratio and could be used as
parts by weight or recipe.
Step 13 However it is more convenient to convert these figures to percentages.
A s already mentioned it makes it easier to compare recipes and to m a k e colour
additions.
67
Glaze No.40.22
Cone 4 (Seger) 1160°C
Formula Requii•ed
Bentonite
.23
.01
K2O
35
.21
.06
.15
.43
Na20
CaO
ZnO
MgO
BaO
AI2O3 Si02
.01
M
M
dl
.00
.34
.03
.30
2.27
.23 ,23
21
1.38
.00
.07
.89
Materials
.13
PV53
Feldspar
Dolomite
Whiting
.03
.31
m
M
.31
.00
2.90
,63
31
.00
Zinc Oxide
21
.21
.00
Barium
.15
A5
.00
Carbonate
Kaolin
Silica
.07
,07
J4
.00
.75
.75
.75
.00
PV53
Bentonite
.13x484 =
62.92
Feldspar
.23 x 556 =
127.88
Dolomite
.03 x 184 =
5.52
Whiting
.31 x 100 =
31.00
Zinc Oxide
.21 x 81 =
17.01
Barium Carbonate
.15 x 197 =
29.55
Kaolin
.07 x 258 =
18.06
19
38
2
9
5
9
5
Silica
.75 x 60 =
45.00
12
336.94
100
Fired to Cone 4 (1160°C) with forty-five minutes soak at top temperature this
glaze was an excellent satin matt slightly opaque. All m y firings are reduced. It
will be seen that the above glaze contains barium carbonate which is a poison and
should be handled very carefully. It is advisable to use gloves and face masks
when handling the dry material.
68
Chapter 7
R A W GLAZES FOR REDUCTION AND OXIDISED ONCE FIRED
PURPOSES
The example used above is the glaze that bears m y number 40.22. A n explanation
of the nomenclature I have used for glaze documentation is necessary, as there is
no universal convention and most glaze technologists seem to develop their o w n
systems. M y original work in the Cone 4 glaze range was numbered as 4.01,
4.02 and so on. The 4 relates to the Seger or Harrison cone number 4 which melts
at 1160° C. 6 4
T h e early glazes were developed for use by students at the
Wollongong Technical College and were designed for use on biscuited pots, that is
pots that have already beenfired.W h e n I decided to pursue the present study with
the glazes n o w designed to be "once" fired, that is to be applied on to the raw or
unfired clay, I simply denoted "once" by adding the letter " O " after the cone
number so the first glaze in the cone 4 range was numbered 40.01 to differentiate
the two types of glaze. It is a convenient system which I have applied to the
various temperature ranges at present under consideration. Once-fired glazes for
1100°C or cone 1 are numbered 10.01, cone 2 glazes are numbered 20.01, cone
3 numbered 30.01, cone 4 will be 40.01, cone 5 will be 50.01 and cone 6 will be
60.01. M a n y of the glazes will be clear and transparent or white and opaque and
when colours in the form of oxides or stains are used or when any modification is
made a note is m a d e along with the glaze details. All m y tests are numbered as
they are m a d e and not all the work results in satisfactory glazes, so in m y results
there m a y be gaps in the continuity of glaze numbers reported as I do not intend to
report on the unsatisfactory ones. O f course with further work these 'discarded'
tests could be developed into usable glazes. However, I have no need to pursue
them at this stage as the successful ones are quite numerous and in true 'Hamada'
style m y work is adequate with a limited range of glazes.
6 % should be noted that Seger cones which I use are numbered differendy to the American Orton
cones which many potters use.
69
Part of m y routine during testing has always been to paint oxide bands on the
unfired glaze surfaces to test for colour response and stability for brushwork
decoration. These colour bands were standardised before painting on the test pots.
In addition, on some tests chromium oxide was tried, as was Leach's copper red
pigment.65 For this recent research the tests resulted in the following colours:
Cobalt oxide & manganese dioxide 50/50 - medium blue
Manganese dioxide
-
good brown
Red iron oxide
-
pale grey green
-
mottled brown
-
mauve purple
* Rutile & red iron oxide 50/50 mix
Copper carbonate
* Unless otherwise noted aU following references to "iron" or "iron oxide" m e a n
red iron oxide.
In compiling this research I completed a literature search in order to assess the
popularity of both mid-fire glazes and once-fired pottery. I already had a fair idea
of the Australian level of studio practice so I chose the influential American journal
Ceramics Monthly as an indicator of what was happening outside Australia. I
carried out a detailed survey of the material published over a period of almost
twenty years and during this time there seems to have evolved a greater interest in
firing pots at temperatures below stoneware mainly for the reasons that I have
already stated, namely the increasing costs of high firing and concern with the
environment. Most of the published material covered glazes that fired at about
1200 degrees centigrade. There was little about the lower temperatures of cones 1
through to 5. It was noticable that there was an almost universal use of gerstley
borate and colemanite as fluxes for lowering the temperatures from the high
stoneware range. There was a great reliance on the American material Albany Slip
which was modified in various ways. Between 1981 and 1994 Ceramics Monthly
published some forty articles or short inclusions relating to mid-fire temperatures.
M a n y were simply responses to requests for information from the technical staff
while others dealt with the subject in greater depth. O n e of these was m y o w n
article Middle Fire Option.66 Others include Cone 5-6 Reduction Glazes by Paul
Woolery, 67 Albany Slip Clay in Oxidation Firing by Richard Zakin,68 Computer
Glazes for Cone 6 Oxidation by Harold J McWhinnie, 6 9 and other as listed in the
Bibliography at the end of this dissertation.
65
Leach's Copper Red Pigment - Feldspar 55, Whidng 22, Silica 14, Tin oxide 3 and Copper
Carbonate 2.
66
Ivan Englund , Middle Fire Option, in C M , April 1985.
67
Paul Woolery , Cone 5-6 Reduction Glazes in C M , April 1982
68
Richard Zakin, Albany Slip Clay in Oxidation Firing in C M May 1982
69
Harold J McWhinnie, Computer Glazes for Cone 6 Oxidation, in C M November 1982
70
A s a more up to date survey I set up a dialogue on the Internet using Clayart. I
had a range of responses which indicate a growing interest in the mid-fire range
rather than a rejection, as suggested by s o m e commentaries. A sample of the
Internet responses follows:
Jeff Brett cited the inclusion of mid-firing in the syllabus of the college at which
he works in Canada. H e wrote:
I feel that mid-temperature ceramics has a great future. I have seen
work locally and in publication that s h o w [sic] the creative and
functional potential of such work. ...I personally work in low and midrange ceramics because of the greater color range and lower firing costs
as well.70
I was encouraged to read from John Neely that:
...Englund's reputation extends beyond Australia. I have used his
book on rock glazes as a resource for glaze formulation classes.
...Englund's assertion that, relative to higher and lower temperature
ranges, the midfire glazes have been neglected historically, is certainly
true. [However,] There are probably m o r e people working with
midfire glazes n o w than ever before.71
Dennis Southwood wrote:
We fire to cone 6 at Mesa College, and have for some time. I guess it
started w h e n energy costs started to rise. I don't k n o w about other
periods in history, but m y impression is that the mid-range
temperatures are getting pretty c o m m o n now. 7 2
Linda Arbuckle pointed me to George Bowes in Cleveland who, "works in cone
5-6, and has for some time".
73
Gloria Pollock responded, "I have been using
Cone 5-6 oxidation glazes both professionally and in my classroom for 20
years."74 Suzanne Wolfe wrote, "Many studio artists in the US (Dorothy Hafner,
for example, used to fire to cone 5, as did Sandy Simon...".75 There were
various other references to cone 5/6 glazes.76
7
fyeff Brett, in Clayart, Pub. online - North Island College, Courtenay, BC, Canada.
(brett@NICAD3.NIC.BC.CA), 10 August 1994
7
* John Neely, in Clayart, Pub. online - Dept of Art, Utah State Uni, Logan, Utah.
(NEELYJC@cc.usu.edu), 11 Aug 1994.
^Dennis Southwood, in Clayart, Pub. online - Mesa College, San Diego.
(dms@powergrid.electriciti.com), 1994.
^Linda Arbuckle, in Clayart, Pub. online - U of FI Dept of Art, Gainesville, Florida.
(ARBUCK@NERVM.NERDC.UFL.EDU), 16 Aug 94
^Gloria Pollock, in Clayart, Pub. online - Pittsburgh, Pennsylvania,
(gpollock@oberon.pps.pgh.pa.us), 10 Aug 1994.
^Suzanne Wolfe, in Clayart, Pub. online - Uni of Hawaii, at Manoa, USA.
(swolfe@uhunix.uhcc.Hawaii.Edu), 10 August 1994.
76
Claudia O'Driscoll, 'Ceramic Arts Discussion List', in Clayart, Pub. online,
(claudiao@MAILHOST,CLACKAMAS.CCOR.US), 17 May 1995, Christine Winokur of
Kickwheel
71
O f significance to this research, there were no responses about once firing other
than one from D o n Jones, w h o wrote, "I have built m y entire business once-firing
white earthenware".77 Periodic scanning of the Internet in the past few months
indicates this same trend of growing interest in mid-fire glazes with only very
occasional references to once firing or raw glazing.78
In the early part of my work I worked a few published formulae to recipes to see
h o w they adjusted to the once-fire concept. This was illustrated in m y detailed
example of glaze number 40.22 which w a s based on a formula published by
Parmelee 79 with the "formula required" line modified to accommodate the use of
bentonite in the glaze. Daniel Rhodes in his Clay and Glazes for the Potter*®
published tables of possible oxide limits for cone 4 glazes but as guidelines they
are only marginally useful. M y long experience in pottery using the Seger formula
method to evolve glazes (as far removed from each other as earthenware glazes for
the Montoro C o m p a n y for use on their roofing tiles and the stoneware glazes
which I have created for m y o w n use in m y more than forty years as a potter) has
equipped m e with the knowledge necessary to readily create the formulae for
original glazes. I have published two books of m y original work, Middle Fire
Pottery*1 and more recently Rock Glazes*2 which is used internationally by some
universities in their ceramics degree courses. I have used the oxides of potassium,
sodium and barium widely as they tend to favour fusion at lower temperatures
more than some others. I have also used the more refractory oxide of magnesium
in m u c h greater amounts than is usually recommended, with good results. The
commercial frits have been used and I have had no hesitation in using soluble
materials. The alumina and silica requirements and relationships vary widely and
of course I have successfully introduced m y knowledge of igneous rocks to the
lower temperatures of middle fired, once-fired glazes. T h e field of middle fire
glazes is very wide and I submit that m y glazes are an important further
contribution to the presently available ceramic knowledge.
The glazes reported in this work were fired in three different kilns, a small 8 cu ft
L P gas fired model by Port-O-Kiln, a 24 cu ft L P gas kiln of m y o w n
construction and a 35 cu ft wood-fired brick kiln. A s already stated I choose to
' 'Don Jones, 'Ceramic Arts Discussion List', in Clayart, Pub. online, (Claysky@A0L.COM),
15 May 1995
'°As stated earlier I do not have my own computer at home. This dictated sporadic access to the
Internet whenever I could use die computer attched to the Ceramics Department at the University
of Wollongong.
79
Warren C Parmelee. Ceramic Glazes. Cahners, N Y , 1973.
80
Rhodes.
81
Ivan Englund. Middle Fire Pottery. Private publication, 1967.
Silvan Englund. Rock Glazes. Private publication, 1983.
72
fire with a reduced atmosphere because it enables the production of such glazes as
the copper reds and the green celadons and I also like the clay colours produced by
reduction. However, I also k n o w from experience that most of the glazes in this
study will fire adequately in oxidized firings and in electric kilns, although the
colours will generally be more bland and celadons and copper reds are not
achievable. However, oxidized celadons can be a veiy good pale amber. Leach 83
gives a recipe for "Old Seto Yellow" which is really a celadon fired in oxidation.
It w a s only w h e n I was able to examine some Old Seto Yellow pots in Nagoya
m a n y years after reading the Leach recipe that I m a d e this connection. While
copper reds are technically not possible in an electric kiln the same copper glaze
will be a very pleasant green. A n alternative copper red can be achieved in an
electric kiln by adding to the glaze a small amount of very fine silicon carbide
which is a local reducer. Dr Lee Angel in Canberra produced these glazes for
m a n y years.
My firing schedule is as follows:
The raw-glazed pots are loaded into the kiln and then fired very slowly up to about
200°C to eliminate the water of plasticity that remains in the clay even w h e n it is
"dry". In other words the pots at this stage are treated in the same w a y as for a
biscuit fire. After 200°C the rate of firing can be increased. I fire m y gas kilns
overnight with only the pilot flame burning. In the morning the temperature is
always near 200°C. T h e fire is continued as normal to the usual biscuit
temperature and then on at the same rate to the glaze maturation temperature. I
usually start the reduction procedure at about 950°C. Reduction too early in the
schedule m a y result in bloated pots and too late m a y m e a n that some colours do
not develop well. I continue the reduction right to the end of the firing. W h e n
temperature is reached it is advantageous to soak for perhaps half an hour to allow
the temperature in the cooler parts of the kiln to even out. After closing off the fuel
I clam up the openings, spyhole and flue to allow slow cooling.
A range of raw glaze recipes follows. All are designed for once firing in the cone
1 - 6 range. The components are listed as percentages by weight. Seger formulae
for most of these recipes are appended at the end of the dissertation.
8
^Leach A Potter's Book.
73
Glaze N o . 1O.01
Cone 1 (Seger) 1100°C
Recipe: Bentonite PV53 19
Feixo Frit 4108
Borax
Feldspar
Result:
41
2
36
Zinc Oxide
1
Silica
1
A good clear glaze, crazed, dependent on the clay
used. This test was on Feeney's E.
In glaze colours Glaze plus . 6 % Chromium Oxide, 5% Tin Oxide
The colour was a very good opaque grey green.
Glaze plus 2% Zinc Oxide, 2% Tin Oxide, 2%
Titanium Oxide and 6 % red Iron Oxide.
This colour fired in reduction was a good solid blue.
In oxidation the colour is a yellow breaking to red.
74
Glaze N o . 1O.03
Cone 1 (Seger) 1100°C
Recipe: Bentonite PV53 22
Fei-ro Frit 4108
42
Feldspar
23
Barium Carbonate
4
Silica
11
Result: A very good clear glaze
Glaze No 10.03 1CH
Glaze plus 1 % Chromium oxide
A n excellent opaque bright green
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
75
Glaze N o . 1O.04
Cone 1 (Seger) 1100° C
Recipe: Bentonite PV53 22
Ferro Frit 4108
39
Whiting
2
Kaolin
10
Barium Carbonate
14
Zinc Oxide
3
Silica
10
Result: A veiy good clear glaze
Glaze 10.04 4C
Glaze plus 4 % copper oxide.
A n excellent dark red with thin green rim.
N O T E : This firing was reduced. With oxidation a clear
green could be expected.
Warning: The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
76
Glaze N o . 1O.05
Cone 1 (Seger) 1100°C
Recipe: Bentonite PV53 18
Ferro Frit 4108
12
Whiting
3
Feldspar
16
Borax
23
B arium Carbonate
18
Silica
10
Result: A slighdy yellowish transparent glaze.
Colours. Having done a great deal of work with this glaze and
others closely related I have m a d e experiments with colour
mostly with combinations of the usual oxides. The
following list could form the basis of colours with other
glazes. Obviously the materials in different glazes can
vary greatly and the colour resulting from the colouring
material will be affected by the differing ingredients. It
should also be noted that the clay body will influence the
colour.
Warning: The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
77
Colour No:
1A
add 2 % Nickel Oxide
IB
add 2% Nickel Oxide 1 % Copper Oxide
1C
add 2% Nickel Oxide, 1% Copper Oxide, 2% Iron Oxide
Dark Olive
2A
add .6% Cobalt oxide
Transparent Blue
2B
add .6% Cobalt Oxide, 2 % Iron Oxide
Dark Blue
3A
add 1 % Copper Oxide
Transparent Green
3B
add 1 % Copper Oxide, 2% Manganese Dioxide
3D
add 4 % Copper Oxide
3C
add 1 % Copper Oxide, 2 Manganese Dioxide, 2 Red Iron Oxide Bottle Green
6B
add 6 % Iron Oxide, 6 Rutile
6C
add 6 % Iron Oxide, 6 Rutile, 6 Zircon Flour
11B
add 2% Manganese Dioxide
11G
add 6% Manganese Dioxide
11F
add 4 % Manganese Dioxide, 4 Iron Oxide
12c
add 2%Iron Oxide
Transparent Dark Brown
13d
add 1 0 % Dolomite
Creamy Opaque
13e
add 6 % Dolomite, 1 % Copper Oxide
13f
add 6% Dolomite, 6% Manganese Dioxide
14a
add 6% Zircon Opacifier Grade
15a
add 4 % Zinc Oxide, 4 % Tin Oxide, 4 % Titanium Oxide
15e
add the above (15a) plus 6% Cobalt Oxide
15f
add 2% Zinc, 2% Tin, 2% Titanium, 6% Iron Oxide
Olive
Olive Green
Transparent Dark Green
Dark Green
Dark Green
Ochre Yellow
Medium brown
Brown
Dark Brown
Grass Green
Coffee Brown
Off White semi opaque
Satin White Opaque
Pale Blue
Dark Orange Red
78
17b
add .6% Chromium Oxide, 6 % Tin Oxide
18a
add 3 % Chromium Oxide, . 3 % Copper, 5%Silica
19b
add . 5 % Cobalt Oxide, .16% Nickel Oxide, .6% Whiting,
3 % Zn Oxide
Grey Green
Bright Green
Pale Opaque Blue
20a
add 2.76% Chromium Oxide, .33% Cobalt Oxide
21b
add .33 Chromium Oxide, 1 Cobalt Oxide, 3 Alumina, 6 Zircon
Opaque Bright Green
Blue
22a add 2.5% Kaolin, .8% Chromium Oxide, 18% Whiting
Bright Green
23a add 1% Chromium Oxide, 2% Zinc, 1% Silica
Opaque Green
24b add .25% Chromium Oxide, 2% Tin Oxide, 1% Whiting,
15% Borax
Green
26b add . 15% Cobalt Oxide, 3% Alumina, .6% Zinc Oxide
Pale Blue
38b add 6% Blythes Yellow Stain No. 235, 6% Zircon
Yellow
39b add 6% Blythes Pink Stain No. 204, 6% Zircon
Pink
41b add 6% Blythes Turquoise Stain No. 110, 6% Zircon
Opaque Blue
42b add 6% Blythes Coral Stain No. 200, 6% Zircon
Brown Coral
44b
add 6 % Blythes Light Green Stain No. 193, 6 % Zircon
45b
add 6 % Blythes Green Stain No. 648, 6 % Zircon
Opaque Pale Green
Green
Apart from the differences in colour that can result from different glazes and
differing clays the kiln atmosphere can affect colour especially those with small
amounts of copper and iron. With copper in oxidation the colour will normally be
green while in reduction the colour can be some variation of red, the so called
"copper red". A small amount of iron oxide in the glaze will be amber in oxidation
and green or grey green in reduction. The best of this colour could be "celadon".
Glaze No. 2O.01
Cone 2 (Seger) 1120°C
Recipe: Bentonite PV53
21
Ferro Frit 4108
30
Feldspar
24
Whiting
4
Zinc Oxide
7
Silica
14
Result: A good clear glaze.
Glaze 11.01 19B
Glaze plus . 5 % CoO, .16% NiO, 3 % ZnO.
Opaque grey blue rather matt.
30.06
Cone 3 (Seger) 1136°C
Semi Opaque
32 Bentonite PV53
Ferro Frit 4108
40
Dolomite
10
Zinc Oxide
8
Whiting
7
Alumina
3
A good grey green slightly milky glaze.
Copper carbonate brushwork can be a
bright red.
81
Glaze N o 30.07
Cone 3 (Seger) 1136°C
Opaque Soft Grey
Recipe: Bentonite PV53 27
Ferro Frit 4108
52
Feldspar
10
Dolomite
6
Whiting
5
Result
The glaze on white clay was a very good opaque soft grey tending slightly
greenish. Oxide brush marks painted on the glaze all bled but gave good blue
with cobalt and manganese mixed, a sharp interesting brown with
manganese while copper carbonate gave a dark grey green. O n a local clay
which fires off white to pale buff the glaze was a good greenish matt with
opalescence in the more heavily glazed areas. The glaze proved to be a good
vehicle for coloured glazes. With . 5 % C o O and 1 % M n 0 2 (numbered
3O.07B) the colour was an opaque pale blue.
The most unusual colour combination tested was the addition of .5% CuC03
and 2 % Sn02 which in some glazes is the basis for copper reds so the glaze
number is 30.07 C R. However copper red in the true sense was absent but
in three firings with slightly differing temperatures and with different setting
combinations of densely packed and lightly packed excellent variations were
achieved. In the coolest part of the kiln the glaze was an excellent opaque
duck egg blue green speckled with purple red throughout. In the kiln centre
where the temperature was a genuine cone 3 the colour was a very smooth
all over delicately mottled pinkish mauve. In the hottest place the glaze ran
(but not over the foot) and became a really good flam be with typical copper
red, opalescent and blue streaks. At the top of the pot (again a bit hotter) the
colour was the usual greenish grey with small patches of red which is usual
with flambe. It seems this glaze could well be fired a cone lower at about
1120°-1130OC.
No. 30.08
Cone 3 1136°C
Opaque Semi Matt White
Feiro Frit 4108
Silica
Whiting
Bentonite PV53
Zircon O P (opacity grade)
Tin Oxide
51
19
14
16
6
4
Excellent opaque white glaze. The zircon andtinneed to
be ground together in a mortar with a drop of water before
being added to the glaze, otherwise the glaze will be full of
white spots.
Adding .5% CoO and 1% Mn02 will result in a pale blue
(number 30.08B) while the usual oxides for copper red,
. 3 % C u C 0 3 and 2 % Sn02 will result in a most unusual
matt flambe colour.
83
Glaze N o . 30.11
Cone 3 (Seger) 1136°C
Recipe: Bentonite PV53 16
Barium Carbonate
4
Zinc Oxide
1
Ferro Frit 4113
71
Silica
9
Result: A very good opalescent blue especially when applied over
black or dark terracotta slip. The blue colour can be
enhanced with the addition of up to . 5 % of either cobalt
oxide or copper oxide.
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
Glaze N o . 30.13
Cone 3 (Seger) 1136°C
( N O T E : Same glaze as 40.13 lower fired)
Recipe: Bentonite PV53
15
Ferro Frit 4108
22
Ferro Frit 4113
22
Feldspar
31
Zinc Oxide
10
Result: Very good opalescent jun.
Glaze 30.13 CS
Glaze plus . 5 % copper slag.
A most unusual effect with the slag evenly distributed as
spots and patches of green, bluegreen, red and metallic
black in a body glaze of cream.
Glaze 30.13 B
Glaze plus 1 % CoO 2 % M n 0 2
Excellent brilliant blue with faint mottle. C u C 0 3 brushing
was varied green and red.
85
Glaze N o 30.13CS
86
Glaze N o . 30.47
Cone 3 (Seger) 1136°C
Bumbo Latite Celadon
Recipe: Bentonite PV53 24
B u m b o Latite
12
Feiro Frit 4108
39
Whiting
2
Barium Carbonate
15
Silica
3
Result: Fired in reduction this glaze proved to be a grey green or
yellow green celadon depending on whether it was applied
to a white or dark clay. Usually it was crazed in a small
pattern. Trailed patterns of opaque glaze number 30.08
O P and blue number 30.08B provided veiy good
contrasts. In m y stoneware work I had had success in
using an igneous rock glaze utilising the Moonbi Granite
near Tamworth to produce a celadon which I then
converted to a copper red by the addition of the usual
oxides, . 3 % C u C 0 3 and 2 % Sn02- A s this B u m b o Latite
glaze was also a celadon having only .02 molecular parts
of iron oxide from the rock in its composition I prepared a
test for a possible copper red. Fired at 1136° C in
reduction it proved to be a superior copper red glaze with
very good coverage.
Warning: The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
87
Glaze N o 30.47
Glaze N o . 30.48
Cone 3 (Seger) 1136° C
Walcha Basalt Glaze
N O T E : Suitable for all basalts
Recipe:
Bentonite P V 53
24
Walcha Basalt
16
Feiro Frit 4108
40
Barium Carbonate
17
Silica
3
Result:
A very good soft grey with some speckle.
Glaze 30.48 F
Glaze plus 1 0 % Fe203
A n excellent dark iron glaze with some iridescence and
varied tea dust, browns and blues.
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
Glaze N o . 30.54
Cone 3 (Seger) 1136°C
N O T E : Glaze 40.54 lower fired
Recipe: Bentonite PV 53
17
Ferro Frit 4108
43
Feldspar
33
Kaolin
5
Silica
2
Result:
Glaze. 30.54 1R
Glaze plus 4 % Fe203, 4 % Rutile.
Very good matt grey blue with pale yellowish spots.
Glaze. 30.54 BB
Glaze plus 2 % CuO, 2 % Ilmenite . 5 % CoO.
Excellent matt green/blue/yellow.
Glaze N o . 40.02
Cone 4 (Seger) 1160°C
Matt Grey
Recipe: Ferro Frit 4108
40
W o o d Ash
45
Bentonite P V 5 3
15
Result: Reserved matt grey which flowed slightly.
Oxide Colour Bands:
All colours flowed badly on this glaze but where broken
colour could be tolerated for its o w n sake the mixed blue
of C o O and M n 0 2 , manganese and probably rutile could be
useful as well as Leach's C u pigment.
Note: Glaze Composition
Because wood ash is very variable in chemical
composition it does not allow itself to be used in the Seger
Formula. It could be analysed but that is an unnecessary
expense. So a recipe such as the above is purely
empirical, one could almost say "seat of the pants"
informed guesswork. In histoiy, for hundreds and
perhaps thousands of years potters evolved glazes in this
manner. Try something, evaluate and adjust it.
91
Glaze N o . 40.04
Cone 4 (Seger) 1160°C
Clear
Recipe: Bentonite PV 53 14
Nepheline Syenite
38
Zinc Oxide
7
Lithium Carbonate
3
Whiting
10
Silica
28
Result: The glaze is a very good clear glaze just off white.
Oxide Colour Bands:
CoO plus M n 0 2
-
strong vibrant blue
Mn02
-
coffee brown
Fe203
-
grey green
Fe203/rutile mix -
opaque dark brown
CuC03
-
dull purple
Chrome oxide
-
opaque green brown
92
Glaze N o . 40.07
Cone 4 (Seger) 1160°C
Basalt Glaze
Bentonite P V 53
Basalt
Barium Carbonate
Zinc Oxide
Dolomite
Whiting
Lithium Carbonate
Silica
Results:
(with various igneous rocks)
No. 40.07 J with Walcha Basalt [John Leah Quarry].
Excellent matt yellow green
Iron brushwork - good brown
No. 40.07 B. with Bumbo Latite near Wollongong.
Excellent deep green.
Iron brushwork - good varied browns.
No. 40.07 R. with Raymond Terrace Dacite.
Very good speckled grey green.
Iron brushwork - dull brown.
15
40
11
4
4
8
2
16
93
Glaze N o . 40.08
Cone 4 (Seger) 1160°C
Frit Glaze
Recipe: Bentonite PV 53 25
Ferro Frit 4108
54
Whiting
10
Kaolin
11
Result: Clear with tiny amount of opalescence.
Oxide Colour Bands:
CoO plus M n 0 2
-
grey blue
Mn02
-
transparent brown
Fe203/Rutile mix-
good ciystal kaki brown
Chrome oxide
-
good green
94
Glaze N o . 40.09
Cone 4 (Seger) 1160° C
Satin Matt
Recipe: Bentonite PV 53 16
Nepheline Syenite
44
Zinc Oxide
7
Barium Carbonate
9
Whiting
8
Silica
16
Result: Excellent satin matt with an almost crystaline surface.
Colour is a pale grey on white clay. On a dark clay the
colour a darker grey due to the clay colour showing
through.
Oxide Colour Bands
CoO plus M n 0 2
-
good bright blue
Mn02
-
dark brown
Fe203/rutile mix -
crystaline brown
CuC03
-
dull brown red
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
95
Further glaze colours:
No. 40.09 B K
Add 1 % C@0, 4 % Fe203, 4 % M n 0 2
Excellent semi matt brownish black with a silvery surface.
No. 40.09 CR Add .3% CuC03, 2% S11O2
Excellent matt copper red. The red is more towards a
sealing wax red. The surface exhibits the same silvery
surface as all the above. This glaze would improve if fired
to a higher temperature.
No. 40.09 B Add 1% CoO, 2% M11O2.
Very good matt royal blue. A smaller amount of colour
oxides could result in a more pleasant blue.
No. 40.09 CC Add .5% CoO, 2% CuO.
Matt dull blue.
No. 40.09 F Add 8% Fe203.
Excellent semi matt dark green breaking to brown on
the rims.
No. 40.09 Y Add 6% Blythes Yellow Stain 235, 6% Zircon flour.
Excellent semi matt. Colour just a tinge of yellow.
96
Glaze N o . 4O.10
Cone 4 (Seger) 1160°C
Opalescent
Recipe: Bentonite PV 53 15
Borax
34
Whiting
9
Magnesium Carbonate
2
Feldspar
13
Kaolin
6
Silica
22
Result: Clear with opalescence in thickly glazed areas.
Oxide Colour bands:
CoO plus M n 0 2
-
good medium blue
Mn02
-
good brown
Fe203
-
pale blue green
CuC03
-
dark purple red
97
Glaze N o . 40.11
Cone 4 (Seger) 1160°C
Shiny Opaque
Recipe: Bentonite PV 53 20
Feldspar
48
Whiting
9
Zinc Oxide
10
Silica
13
Result: A beautiful opaque shiny glaze very nearly white. With
some of these "Once-fire" glazes occasionally there will be
a slight flake off at the edges. Simply touch up any such
areas with a brush when diy.
Oxide Colour Bands:
C o O plus M n 0 2 -
blue black
Mn02
-
matt coffee brown
Fe203
-
yellow green
Fe203/Rutile mix-
opaque coffee brown
CuC03
-
metallic brown-red halo
Glaze N o . 40.13
Cone 4 (Seger) 1160°C
This recipe is based on the calculations in Glaze No. 40.54.
Recipe: PV 53
15
Ferro Frit 4108
22
Ferro Frit 4113
22
Feldspar
31
Zinc Oxide
10
Result: Excellent rich opalescent blue
Oxide Bands:
Cobalt &Manganese -
good medium blue
Manganese
-
varied yellow to brown
Copper Carbonate
-
mottled red
All oxides bled into the glaze but the colour results indicate that the glaze
would be an excellent vehicle for most colours.
99
Glaze N o 40.13
100
Glaze N o . 40.22
Cone 4 (Seger) 1160°C
Satin Matt Opaque Celadon
Recipe: Bentonite PV53 19
Feldspar
38
Dolomite
2
Whiting
9
Zinc Oxide
5
Barium Carbonate
9
Kaolin
5
Silica
13
Result: The glaze is an excellent Satin Matt opaque celadon green.
Oxide Colour Bands:
CoO plus M n 0 2
-
excellent blue
Mn02
-
good brown
Fe203
-
pale grey green
Fe203 plus Rutile-
good speckled brown
CoO
-
dull purple
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
101
Glaze N o 40.22
102
Glaze N o . 40.23
Cone 4 (Seger) 1160°C
Blue green celadon
Recipe:
Result:
Bentonite P V 53
19
Soda Ash
22
Feldspar
10
Whiting
8
Barium Carbonate
24
Silica
17
The glaze is an excellent bluish green celadon of excellent
quality.
Oxide Colour Bands:
rich dark blue
CoO & M n 0 2
dark purple brown
Mn02
pale blue
Fe203
Fe203 Plus Rutile-
green to brown
CuC03
good purple red
Leach C u Red pigment-
ex.copper red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
masks when
very carefully.
It is advisable to use gloves and face
handling the dry material.
103
'
*
Glaze No 40.23CR
104
Glaze N o . 40.24
Cone 4 (Seger) 1160°C
Opaque
Recipe:
18
32
3
10
15
9
13
Bentonite P V 53
Feldspar
Dolomite
Borax
Whiting
Kaolin
Silica
Result:
A very smooth, slightly greenish opaque matt.
Oxide Colour Bands:
CoO plus M n 0 2
-
very dark blue
Mn02
yellow brown
Fe203
pale grey green
Fe203/rutile mix -
very dark brown
C0CO3
pale grey purple
105
Glaze N o . 40.25
Recipe:
Cone 4 (Seger) 1160°C
16
34
23
11
16
Bentonite P V 53
Feldspar
Borax
Whiting
Silica
Result:
Good transparent tending towards pale green
Oxide Colour Bands:
CoO plus M n 0 2
-
strong inky blue
Mn02
dark brown
Fe203
olive green
Fe203/rutile mix -
dark brown
CuC03
dark purple red
Leach C u red pigment-
dark purple red
Chrome oxide
-
yellow green
106
Glaze N o . 40.26
Cone 4 (Seger) 1160°C
Clear
Recipe: Bentonite PV53 21
Feldspar
11
Borax
32
Lithium Carbonate
Whiting
2
11
Zinc Oxide
6
Silica
17
Result: Good clear glaze with some opalescence in thickly glazed
areas.
Oxide Colour bands:
CoO plus M n 0 2
- good blue which bled badly
Mn02
-
coffee brown
Fe203
-
grey green
CuC03
-
varied green to red
Leach C u pigment-
excellent copper red
107
Glaze N o . 40.28
Cone 4 (Seger) 116QOC
Opaque Matt
Recipe:
Bentonite P V 5 3
19
Feldspar
23
Dolomite
7
Borax
10
Whiting
11
Barium Carbonate
6
Silica
Result:
24
Very good reserved matt slightly blue. The glaze did not
heal over slight imperfections. Perhaps it could be fired to
a higher temperature.
Oxide Colour Bands:
CoO plus M n 0 2
good matt purplish blue
Mn02
yellow brown
Fe203
grey green
Rutile
almost black brown
C0CO3
dull green
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
masks when
very carefully.
It is advisable to use gloves and face
handling the dry material.
108
Glaze N o . 40.32
Cone 4 (Seger) 1160°C
Clear
Recipe: Bentonite PV53 18
Borax
21
Whiting
13
Barium Carbonate
17
Kaolin
9
Silica
22
Result: A good transparent clear glaze tending towards pale green
because of the reduced firing.
Oxide Colour Bands:
CoO plus M n 0 2
-
strong dark blue
Mn02
-
strong brown
Fe203
-
olive green
Fe203/rutile mix -
crystal brown
CuC03
-
dull metallic brown red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
109
Glaze N o . 40.33
Cone 4 (Seger) 1160°C
Clear
Recipe: Bentonite PV53 18
Borax
23
Podmore Frit P2244
5
Zinc Oxide
4
Whiting
9
Kaolin
11
Silica
30
Result: Very good clear tending grey green.
Oxide Colour Bands:
CoO plus M n 0 2
-good medium blue which bled
Mn02
-
sharp brown
Fe203
-
grey green
Fe203/Rutile mix-
crystaline brown
CuC03
-
Leach C u red pigment-
dark purple red
good copper red
110
Glaze N o . 40.34
Cone 4 (Seger) 1160°C
Clear
Recipe:
Result:
Bentonite P V 53
16
Borax
24
Podmore Frit P2244
5
Barium Carbonate
8
Dolomite
4
Zinc Oxide
2
Whiting
6
Kaolin
14
Silica
21
Very good clear glaze tending towards greyish
celadon.
Oxide Colour Bands:
CoO plus M n 0 2
-
dark blue, slight bleeding
Mn02
dark brown
Fe203
pale grey green
Fe203 plus rutile CuC03
dark speckled browns
metallic dark red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
Ill
Glaze N o . 40.38
Cone 4 (Seger) 1160°C
Matt
Recipe:
Bentonite PV53
21
Nepheline Syenite
28
Feldspar
20
Whiting
20
Barium Carbonate
2
Silica
9
Excellent satin matt.
Result:
Oxide Colour Bands:
CoO plus M n 0 2
strong vibrant blue
-
Mn02
dark brown
Fe203
pale green
Fe203/rutile mix -
varied browns
varied red
CuC03
Leach C u red pigment-
clear pink red
grey-brown
Cr 2 03
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
112
Glaze N o . 40.39
Cone 4 (Seger) 1160°C
Matt
Recipe:
Bentonite PV53
25
28
7
22
18
Whiting
Lithium Carbonate
Kaolin
Silica
Result:
Good matt glaze.
Oxide Colour Bands:
CoO plus M n 0 2
-
Mn02
Fe203/rutile
CuC03
Leach C u pigmentChrome oxide
medium blue
medium brown
veiy rough surface
copper green
good pink
brown black
113
Glaze N o . 40.51
Cone 4 (Seger) 116QOC
Semi Matt
Recipe:
Result:
Bentonite PV53
21
Nepheline Syenite
40
Whiting
6
Zinc Oxide
8
Barium Carbonate
12
Silica
13
Excellent smooth semi matt tending towards blue green.
Oxide Colour Bands:
CoO plus M n 0 2
-
bright medium blue
Mn02
pale beige
Fe203
good grey green
Fe203/rutile mix -
dull matt brown
copper red
Q1CO3
Leach C u pigment-
matt copper red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
114
Glaze N o . 40.52
Cone 4 (Seger) 1160°C
Raymond Terrace Dacite Glaze
Recipe: Bentonite PV 53 20
Raymond Terrace Dacite
20
Whiting
15
Borax
24
Barium Carbonate
Silica
9
12
Result: The glaze was a medium yellow green transparent colour
which flowed though it stopped short of the foot.
Colour Oxide Bands:
All flowed badly mling out oxide brushwork decoration.
CoO plus Mn02 - good medium blue
Mn02
-
medium brown
Fe203
-
grey green
Fe203/rutile mix -
dark brown
CuC03
- very good varied copper red
Warning: The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
115
Glaze N o . 40.53
Cone 4 (Seger) 1160°C
Jun Blue
Recipe:
Result:
Bentonite P V 5 3
16
Feldspar
34
Borax
23
Whiting
11
Silica
15
This glaze resul
next No. 40.54. Refer to earlier notes regarding m y use
of soluble materials.
Colour No. 40.53 BB (Beryl's Blue)
add 2 % CuO, 2 % Ilmenite and . 5 % C o O
The oxide combination in this glaze results in a varied
mottled green/blue/ochre depending on the thickness of
glaze application.
116
Glaze N o . 40.54
Cone 4 (Seger) 1160°C
Jun-like Blue
Recipe: Bentonite PV 53 18
Feiro Frit 4108
42
Feldspar
32
Kaolin
56
Silica
2
This glaze is another version of the previous one No.
40.53 for they have virtually the same molecular formula.
The difference is that the soluble borax is eliminated and
Ferro Frit 4108 substituted to overcome the fears and
prejudices of some potters.
Result: The glaze is always a jun-like blue which while
satisfactory on white clay is more spectacular over dark
clay or black slip.
The blue is not quite as strong as in N o . 40.53. The
borax
ingredient seems to favour the formation of the blue more
than does the frit. The tiniest amount of C o C 0 3 added will
add to the solidity of the blue colour but tends to degrade
the opalescence of the chun effect.
The addition of m y favourite mixture of oxides: 2 % CuO,
2 % Ilmenite and .5 C o O %
will result in a spectacular
mottled or speckled colour of blues, greys, yellow, greens
and red. A painter friend likened the mixed colours to the
effects of the pointillist painters of the post impressionist
period.
117
Glaze N o 40.54
N o . 50.01
Cone 5 (Seger) 118Q0C
Bentonite P V 53
19
Feldspar
58
Zinc Oxide
6
Whiting
10
Silica
7
The glaze is an excellent semi-matt tending towards a blue
celadon. Non crazed on Clayworks S W E Clay and
Feeney E.
Bands:
Cobalt/manganese mix -
excellent dark blue.
Fe203
-a good yellowish brown
CuC03
-
an opaque pink red
119
Glaze N o 50.01
120
Glaze N o . 50.02
Cone 5 (Seger) 1180°C
Recipe Bentonite PV 53 24
Feldspar
Zinc Oxide
8
Whiting
17
Kaolin
3
Result: A reserved stony matt opaque glaze.
Colour Band:
48
The blue was a strong dark colour.
121
Glaze N o . 50.07
Cone 5 (Seger) 1180°C
Recipe: Bentonite PV53 14
Feldspar
18
Whiting
12
Lithium Carbonate
14
Kaolin
20
Silica
22
Result: A very good semi-matt opaque on SWE clay and a solid
grey matt on Feeney E.
122
Glaze N o . 5O.10
Recipe:
Cone 5 (Seger) 1180C
Bentonite P V 53
17
Whiting
13
Barium Carbonate
Result:
4
Feldspar
55
Silica
11
Excellent smooth, uncrazed opaque on S W E clay and
smooth grey on Feeney E.
Colour Bands:
Blue
very nice blue
Iron Oxide
yellow brown
CuC03
good pink red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
123
Glaze N o . 50.11
Cone 5 (Seger) 1180°C
Recipe: Bentonite PV 53 23
Feldspar
35
Whiting
7
Barium Carbonate
15
Zinc Oxide
12
Silica
8
Result: The glaze is a good semi-matt which combines well with
blue pigments.
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
124
Glaze N o . 5 0 . 1 2
Recipe:
Cone 5 (Seger) 1180°C
Bentonite P V 53
23
Whiting
7
Barium Carbonate
22
Zinc Oxide
8
Kaolin
17
Silica
23
Result: I have a personal dislike for so-called "dry" glazes i.e.
glazes which either haven't melted or are overloaded with
one or other of the oxides. T o m e glaze means melted.
However, the above glaze while being a "dry" glaze has
quite a pleasant matt surface. A warning is often given
that such glazes should not be used for food containers.
In any case the rough surface is quite unsuitable for such
use. This glaze would be useful on sculptural pieces.
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
masks when
very carefully.
It is advisable
handling the dry material.
to use gloves and
face
125
Glaze N o . 60.02
Cone 6 (Seger) 1200°C
Matt
Recipe:
Bentonite P V 53
18
Feldspar
58
Whiting
10
Barium Carbonate
11
Silica
Result:
3
This glaze is a very good opaque semi matt.
Oxide Colour Bands:
CoO plus M n 0 2
good medium blue
beige to brown
Mn02
Fe203
pale green to grey olive
Fe203/rutile mix
dull brown
CuC03
matt purple pink
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
126
Glaze N o . 60.05
Cone 6 (Seger) 1200°C
Smooth Celadon
Recipe:
Bentonite PV53
Dolomite
Feldspar
Borax
Whiting
Kaolin
Silica
Result:
17
3
30
5
16
5
25
Excellent smooth greyish celadon on dark clay.
Oxide Colour Bands:
CoO plus M n 0 2
good dark blue
Mn02
coffee brown
Fe203
grey green
CuC03
dull greyish purple red
127
Some colours:
No. 60.05 F10 Glaze plus 10% Fe203
excellent green and brown tea dust.
No. 60.05 F4 Glaze plus 4% Fe203 is a very good
smooth matt green.
No. 60.05 OP Glaze plus 4% Zircon flour, 4% Tin Oxide
smooth pale beige.
No. 60.05 CMR Glaze plus 5% CoO, 1% Mn02, 2%
Rutile
transparent dark grey blue.
128
Glaze N o . 60.09
Cone 6 (Seger) 1200°C
Semi Matt
Recipe:
Bentonite P V 53
20
Dolomite
9
Feldspar
39
Whiting
9
Barium Carbonate
8
Silica
Result:
15
The glaze is an excellent smooth off white.
Oxide Colour Bands:
green medium blue
CoO plus M n 0 2
Mn02
coffee brown
Fe203
olive green
Fe203/rutile mix
olive green
good mauve pink
CuC03
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
129
Glaze N o . 60.11
Cone 6 (Seger) 1200°C
Smooth off White
Recipe: Bentonite PV 53 22
Feldspar
47
Whiting
4
Barium Carbonate
15
Zinc Oxide
11
Silica
1
Result: A good smooth off white. Non crazed but that would
depend on the clay used.
Colour Response:Oxide bands painted on unfired glaze.
Co0+Mn02
-
blue, very good medium to dark blue
Mn02
-
brown
Fe203
-
olive
Rutile
-
brown
CuCo3
-
purple red
Ci"203
-
olive brown
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
130
Glaze 60.12
Cone 6 (Seger) 1200°C
Opaque White
Recipe: Bentonite PV 53 21
Feldspar
31
Zinc Oxide
26
Silica
22
Result: Very good reserved opaque white.
Oxide Colour Bands:
CoO plus M n 0 2
-strong purple blue tending to flow
Mn02
-
coffee brown
Fe203
-
pale green
Fe203/rutile mix -
crystal brown
CuC03
-
brown red
Leach C u pigment-
pink
Glaze N o . 60.14
Cone 6 (Seger) 1200°C
Clear
Recipe:
Result:
Bentonite P V 53
20
Feiro Frit 410 8
8
Feldspar
44
Whiting
18
Kaolin
2
Silica
8
A good transparent clear tending towards yellow g
Oxide Colour Bands:
C o O plus M n 0 2
-
strong blue
Mn02
dark chocolate
Fe203
pale green
Fe203/rutile mix CuC03
Leach C u red pigmentChrome
olive
good purple red
excellent red
good olive green
132
Glaze N o 60.14
133
Glaze N o . 60.15
Cone 6 (Seger) 1200°C
Pale greyish celadon
Recipe: Bentonite PV53 19
Feiro Frit 4108
8
Feldspar
38
Barium Carbonate
2
Silica
17
Whiting
16
Result: An excellent smooth pale slightly greyish celadon.
Oxide Colour Bands:
CoO plus M n 0 2
-
very dark blue
Mn02
-
shaip brown
Fe203
-
pale green
Rutile & iron
-
dark olive
CuO
-
good pink red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
134
Glaze N o 60.15
Glaze N o . 60.18
Cone 6 (Seger) 1200°C
Clear
Recipe: Bentonite PV 53
22
31
16
14
4
11
Nepheline Syenite
Whiting
Barium Carbonate
Lithium Carbonate
Silica
Result: A clear off white glaze.
Oxide Colour Bands:
C o O plus M n 0 2 Mn02
-
pleasant blue bled badly
brown which bled badly
Warning: The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
136
Glaze N o . 60.21
Cone 6 (Seger) 1200°C
Opaque
Recipe:
Bentonite P V 53
19
Feldspar
66
Whiting
6
Zinc Oxide
9
Result: A very reserved opaque glaze.
Oxide Colour Bands:
CoO plus M n 0 2
Mn02
veiy dark inky blue
-brown
Fe203
pale brown
Fe203/rutile mix
matt chocolate brown
137
Glaze N o . 60.22
Cone 6 (Seger) 1200°C
Granite Celadon
Recipe: Bentonite PV 53 18
Granite dust
40
Barium Carbonate
11
Whiting
14
Silica
17
Result: This glaze was a very good slightly speckled green. The
granite was sieved through on 80 mesh sieve (.0071 m m ) .
With ball milling to afinermaterial the specks would be
eliminated.
With the addition of 1 0 % Fe203 the glaze became an iron
black. Fine grinding of the glaze was necessary.
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
138
Glaze N o . 60.25
Cone 6 (Seger) 1200°C
Opaque Semi Matt
Recipe:
Bentonite P V 53
22
Feldspar
27
Dolomite
7
Whiting
15
Zinc Oxide
4
Silica
Result:
25
Very good reserved semi matt glaze.
Oxide Colour Bands:
CoO plus M n 0 2
-
quiet grey blue
Mn02
-
medium brown
Fe203
-
grey green
Fe203/rutile mix -
olive to brown
139
Glaze No. 60.26
Cone 6 (Seger) 1200°C
Matt
Recipe: Bentonite PV 53 22
Soda Feldspar
57
Whiting
13
Soda Ash
4
Zinc Oxide
4
Result: Excellent matt glaze.
Oxide Colour Bands:
C o O plus M n 0 2 -
matt mid-blue
Mn02
-
brown
Fe203
-
olive grey
CuC03
-
copper pink
140
Glaze N o . 60.27
Cone 6 (Seger) 1200°C
Opaque semi-matt
Recipe: Bentonite PV 53 18
Feldspar
58
Soda Ash
3
Whiting
8
B arium Carbonate
11
Silica
2
Result: Very good opaque semi matt.
Oxide Colour Bands:
CoO plus M n 0 2
-
strong opaque blue
Fe203
-
olive grey green
CuC03
-
pink red
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
141
Glaze N o 60.27
142
Glaze N o . 60.28
Cone (Seger) 1200°C
Average Basalt Glaze
Recipe: Bentonite PV 53 20
Average basalt
44
Whiting
4
Barium Carbonate
3
16
Zinc Oxide
Result: This glaze was developed to use any basalt where the
analysis was unknown or unavailable. The glaze is
suitable for other igneous rocks as well.
No. 60.28 R Raymond Terrace Dacite.
Off white almost clear.
No. 60.28 B Bumbo Latite.
Veiy good smooth olive green.
No. 60.28 W Walcha Basalt
Excellent almost black olive turning yellow where thin
No. 60.28 Gl Glen Innes Basalt
Excellent dark crystalline brown, yellow where thin
No 60.28 GS Mr Gibraltar Syenite
Dark mottled with green
Warning: The above glaze contains barium carbonate which is a poison and
should be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
143
Glaze N o . 60.29
Cone 6 (Seger) 1200°C
Clear
Recipe:
Result:
Bentonite PV53
13
Frit P2244
24
Feldspar
23
Magnesium Carbonate
4
Kaolin
9
Silica
27
A good semi transparent glaze tending towards.yellow
green.
Oxide Colour Bands:
CoO plus M n 0 2
-
blue black
purple brown
Mn02
pale brown
Fe203
Fe203/rutile mix -
matt dark brown
CuC03
brown red
Leach C u red pigment-
brown red
Chrome oxide
-
unmelted green
144
Glaze N o . 60.30
Cone 4 (Seger) 1160°C
Clear
Recipe:
Bentonite P V 53
17
Borax
21
Whiting
14
Barium Carbonate
17
Kaolin
9
Silica
22
Result: Very good clear glaze tending towards celadon.
Oxide Colour Bands:
CoO plus M n 0 2
-intense inky blue which bled slightly
Mn02
-
dark coffee brown
Fe203
-
green brown
Fe203/rutile mix -
crystal brown
CuC03
-
metallic purple brown
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should be handled very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
145
Glaze N o . 60.44
Cone 6 (Seger) 1200°C
Clear
Recipe:
Result:
Bentonite P V 53
17
Feldspar
31
Dolomite
3
Whiting
18
Kaolin
5
Silica
26
A good white semi matt.
Oxide Colour Bands:
CoO plus Mn02i!iMn02
Fe203
Fe203/rutile mix CuC03
strong blue black
brown
pale green
strong brown
pale mauve
146
Glaze N o . 60.60
Cone 6 (Seger) 120QOC
Recipe: Bentonite PV 53 21
Feldspar
26
Dolomite
1
Talc
19
Borax
12
Zinc Oxide
15
Kaolin
5
Silica
1
Resuk: A good shiny opaque glaze the colour of which in my test
was a beige-brown from the iron picked up from the
Feeney E clay.
147
Glaze N o . 60.61
Recipe:
Cone 6 (Seger) 1200°C
Bentonite P V 53
20
Ferro Frit 4108
15
Feldspar
38
Whiting
19
Silica
7
Result: Good clear grey green. The green colour probably results
from iron pickup from Feeney E clay.
148
Glaze N o . 60.62
Cone 6 (Seger) 1200°C
Recipe: Bentonite PV 53 120
Result:
Feldspar
37
Talc
18
Zinc Oxide
17
Lithium Carbonate
1
Kaolin
3
Silica
5
Excellent smooth opaque white.
N o . 60.63
Cone 6 (Seger) 1200°C
Bentonite P V 53
24
Ferro Frit 4108
50
Magnesium Carbonate
Kaolin
9
17
A very good clear to pale green glaze. The green is due to
the pick up of iron oxide from the Feeney E clay.
150
Glaze N o . 60.65
Cone 6 (Seger) 1200°C
Bentonite P V 53
14
3
1
35
6
5
13
23
Feiro Frit 4108
Dolomite
Feldspar
Borax
Barium Carbonate
Whiting
Silica
Result:
The glaze was an excellent clear tending towards celadon
because of the pick up of iron from the Feeney E Clay.
Warning: The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
151
Glaze N o . 60.66
Cone 6 (Seger) 1200OC
Recipe: Bentonite PV 53 16
Whiting
12
Feldspar
30
Barium Carbonate
16
Zinc Oxide
2
Silica
24
Result: This glaze is a superior opaque pale green the opacity
resulting in part to myriads of tiny enclosed bubbles. The
celadon like green occurs through the solution of iron
oxide from the surface of the Feeney E Clay
W a r n i n g : The above glaze contains barium carbonate which is a poison and
should
be handled
very carefully.
It is advisable to use gloves and face
masks when handling the dry material.
BIBLIOGRAPHY
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November (1982): 54-55.
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..., "Cone 3-8 Rutile Glazes." Ceramics Monthly May (1986): 73.
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APPENDIX 2
Clay
CLAY
While this work specifically deals with ceramic glazes it should be emphasised that glazes
cannot be considered separately from the clays or clay bodies upon which they are
applied. In this study I have used several commercially available clays as well as m y o w n
traditionally prepared bodies. In the early stages of this research I used m y stoneware
clay, Walkers PB103. This was reasonably successful at the higher temperatures in m y
study but was too porous in m y opinion at the lower. I then used Clayworks S W E as a
near white body and Feeney's E as a darker clay both proving very satisfactory, easily
thrown and satisfactory in the kiln. M y o w n personally prepared clay was very good also
but it is based on a local material not generally available. However, I did m a k e many
tests of clay bodies mixed from milled materials and which were successful at the
"middle" temperatures of this study. These are easily prepared.
Body 1 This is a near white body, quite
plastic with small shrinkage.
Kaolin
20
Silica
35
Ball Clay
Nepheline Syenite
30
15
Body 2 An excellent wheel clay. Fires water
tight at Cone 4 but can be fired to
stoneware.
Kaolin
31
Ball Clay
31
Nepheline Syenite
25
Silica
13
Bod
y
3
A white plastic body, non porous at
Cone 4 and above.
Ball Clay 50
Silica
17
Feldspar
Bod
y
4
33
Good throwing body. Its whiteness
depends on the choice of both kaolin
and
ball clay, non porous at Cone 4.
Kaolin
35
Ball Clay
20
Silica
25
Nepheline Syenite
20
Body 5 A good throwing clay which fires
well at Cone 4 and is coloured by the
red clay.
Kaolin
27
Ball Clay
9
Silica
23
Nepheline Syenite
18
Red Clay
23
APPENDIX 3
The Exhibition
BLOOMFIELD
GALLERIES NEWS! NEWS! NEWS!
The
Bkxxiifielcl
Galleries
Lin has returned from her trip to France and Spain filled with enthusiasm for Australian art today. "Even though our
artists suffer from the tyranny of distance and consequent lack of access to major museums, they are right up
there w h e n it c o m e s to expertise In painting and sculpture across a broad spectrum of subject matter and our
commercial galleries compare very favourably with those I saw", she says. Highlights of the trip were the Matisse
exhibition at Georges Pompidou, the Titian and Amenoteph III at the Petit Palais and the Zadklne at the Musee
Zadkine In Paris; the Prado, M u s e u m of Contemporary Art and the new Thyssen Bornemlsza M u s e u m in Madrid.
In her new capacity as consultant to the Gallery under the directorship of Jane, Lin will be In attendance at the
Gallery by appointment only on Wednesdays for valuations and authentications and also be available for hanging
collections both private and corporate.
This month Bloorrfleld Galleries Is holding a Norman Lindsay exhibition with a difference. Fifty two small pen and
pencil drawings from a folio personally collected by Rose Lindsay and dating from 1900 are a fascinating Insight
into Rose's preferences. Pen drawings from Vfefon, studies for published works, Springwood compositions, single
figure nudes, motifs for decorations, pen and pencil compositions and numerous others including a kookaburra
study comprise this unique exhibition.
van" Englund, Walcha based potter, will be shnwjn^frnm Tuesday August 31 tojSeptember 18. Represented In
state and regional galleries andjiniverettte^TrTAustralia, Japan, U S A , ChinF^ncTRnssia^Jyan Is currently
completing his Doctojjle-of^feative Arts at the University of Wollongong. This exhibition, IvanVTkst major solo
Sydney showtef-ZtTyears will feature exciting n e w glazes on a variety of superb pots. All ofjfje-pots exhibit his
preferencS'for simple, conventional shapes, are wheel thrown arid^we_b2JjjhJox-deeorattorTln wax, cobalt and
peuoxidsa,
—
Lin's visit to Bulgaria last year proved very successful. Since the collapse of communism a new Ministry for the
Arts Is being formed and Lin had meetings with the dynamic Minister of Culture In Sofia (Professor Elka
Konstantinova) and, In Varna, the Director of the Varna Art Gallery, foremost Bulgarian artist Vanko Urumov.
Privately conducted tours of galleries and visits to artist's studios were arranged. A highlight w a s the trip to the
Tryavna Art School with its ancient tradition of wood sculpture. Bloomfield Galleries will be holding a showing of
works by Todor Velln, a Bulgarian artist n o w living In Sydney from late September to early October.
October is Reinhard month! Professor Ken Reinhard, Dean and Director of the College of Fine Arts, University of
N S W Is widely represented In state and regional galleries, universities and private collections In Australia and
overseas. H e has represented Australia in exhibitions In France, U S A , N e w Zealand and Yugoslavia in a variety of
media and since his first exhibition at the Macquarie Galleries In 1964 and has been a prominent figure In Ihe
Australian art world. Ken's work has always been controversial and this exhibition. The Naked Chair, promises to
be a show sfopperl
During the first week in November, marine artist Peter Yeomans will be showing his new works, the Venetian
Series Peter studied at East Sydney Technical College and St Marlins School of Art, London and In 1988
obtained his post graduate diploma In painting from the College of Fine Arts, University of N S W . Although wel
known as a marine artist he has approached diverse subject matter with notable success. In 1993 his Pilot
Boarding won the prints and drawing category prize at the P 8,0 Awards, Australian Maritime Museum.
In November we will be sending out our last newsletter of the year with information about our final exhibition for
1993.
BLOOMFIELD GALLERIES NEWSLETTER - WINTER 1993
118 Sutherland Street, Paddlngton N S W 2021 Australia Ph: (02)326 2122 Fax: (02) 327 8148
Gallery Hours: Tuesday - Saturday 1:00-6:00pm
A DMelon of N M Bloomfield Holdlnoe Ply Limited A C M 002 «»» »59
IVAN ENGLUND
DAVE WOOD
GLEN MANNING
CALLIGRAPHY
CERAMICS
M A J O R EXHIBITION O F N E W W O R K
31 August - 18 September 1993
New England Landscape, 1993
ht 43 cm
The Bloomfield Galleries
118 Sutherland Street, Paddington N S W 2021
Phone: (02) 326 2122 Fax: (02) 327 8148
Tuesday - Saturday 1:00 pm-6:00 p m
ALAN F O X
EXHIBITION 6-28 AUGUST, 1993
OLD BAKERY GALLERY
22 Rosenthal Ave, Lane Cove 2066. PO Box 193. Tel: (02) 428 4565
Gallery Hours: 10 am to 5 p m Tuesday to Saturday
Studio Altenburg
AMINITE', 1993. HANDBLOWN GLASS FORM
JANE STURROCK NASH
FOX STUDIO GLASS
cl- POST OFFICE, KARRIDALE, W. AUSTRALIA 6288.
TELEPHONE: (097) 586 712
1 OCTOBER-2 NOVEMBER, 1993
104 Wallace Street, Braidvoood, NSW 2622
Telephone: (048) 422384
OPFN 10 AM TO 5 PM EVERY DAY
IVAN ENGLUND
NEW ENGLAND
LANDSCAPES
An invitation to attend the opening
of this major exhibition on
Tuesday 31 August 1993 from 6:00pm - 8:00pm
Exhibition extends until 18 September 1993
118 Sutherland Street, Paddington NSW 2021
Phone: 326 2122
Fax: 327 8148
NEW ENGLAND LANDSCAPES
Catalogue Statement
Making pots is not just about pushing clay into s o m e sort of shape and firing it though at its simplest it
could be just that. A lifetime could be spent in the study of clays and rocks, the geology of which is the
very basis of pottery. Then there is the interest of h o w clay is shaped. The most direct method of
making a pot is to build it by hand from coils or slabs. M a n y potters still use the potters wheel in one of
its m a n y forms to skilfully shape the clay. Slip casting allows not only the repetition of forms but allows
unlimited control of shapes. There is scope for designers of pottery forms for factories or for studies
and s o m e workers are interested only in decoration or painting. To complete a pot it must be fired so
there is a wide field of study in kiln design and building, in fuels and in the various effects of both kiln
and fuel best illustrated by the "fire" marks and slaglike glazes beloved of the wood firers with their
Bizen type a n a g a m a kilns and by the potters w h o "salt glaze" pots by throwing c o m m o n salt into the
hot kiln. Then there are real glazes. Glaze is closely allied to glass where certain substances are
mixed and fired to a temperature where they melt to b e c o m e glass. The glass worker forms the shape
while the glass is in the molten state while the potter applies the glaze mixture to the pot surface to
b e c o m e molten w h e n fired.
I have been fascinated by glazes throughout my long career as a potter. I have formulated low fire
glazes for a commercial roofing tile company and for m a n y years I worked exclusively in stoneware
fired at 1250oC to 1300oC. Glazes can be rough and stony, transparent and glasslike with or without
grazing (or crackle!), opaque either in white or offwhite, they can be heavily laced with iron oxide to
produce the black tenmokus, tan/orange kaki or greenish crystalline "tea-dust" of oriental pottery. With
a minute amount of the s a m e iron oxide it is possible to achieve the incomparable green oeladon "like
the blue of the sky after rain". Glazes can be stained with the various metal oxides, cobalt for blue,
manganese for brown purple, chrome for dense green and copper for the incredible "copper red", the
flambes, the peach blooms and the sang de boeufs. Modern chemists have produced a vast array of
stains with which to colour glazes.
Many years ago at the Wollongong Technical College I began an investigation into an area of
temperatures that had been largely neglected over the centuries; that is the glazes that would be fired
at cone 4 or 1160oC. I called such glazes "middle fire" to differentiate them from earthenware and
stoneware. In 1990 I started work and research for the degree of Doctor of Creative Arts at the
University of Wollongong and chose to further m y research into the middle fire glazes this time
calculating them to be applied to the unfired pots, the so-called "once fire" or "raw glaze" technique
rather than the more usual method of applying the glaze to an already fired pot.
The present exhibition shows glazes developed over the last three years in the temperature range of
1100oC and 1200oC and constitutes part of m y presentation together with m y written submission for
the Doctor of Creative Arts degree. All the pots have been thrown on a potters wheel in deliberately
simple shapes to allow the glazes full attention. The decoration is simple using wax, cobalt and copper
oxides. I present this work as proof of m y thesis that excellent glazes are achievable in the middle fire
temperature range.
Ivan Englund
BLOOMFIELD GALLERIES
IVAN ENGLUND
31 August -18 September 1993
NEW ENGLAND LANDSCAPES
TITLE
DATE
GLAZE
SIZE (mm)
PRICE
1. Pared*
1993
Celadon Glaze
280
$200
2. Towards Evening
1993
Chun Glaze
300
$200
3. B I I M Streamer
1993
Red, White and Blue
304
$200
4. Valley Mist
1993
Chun Blue Glaze
320
$250
5. Variations In Blua
6. H o m a g e to Beryl's Blue
7. Potntlllst Platter
1993
Chun Blue Glaze
330
$250
1993
Ilmenite Glaze
$250
1993
Ilmenite Glaze
350
356
$250
B. Seaside
1993
Cobalt Glaze
360
$250
9. Misty Morning
1993
Chun Glaze
325
$260
10. Fiery Landscape
1993
Copper Red Glaze
360
$260
11. Gesture In Blue
1993
Blue and White
295
$275
12. Celebration in Red
1993
Copper Red Glaze
340
$275
13. Dreams of S u m m e r
1993
Red and Blue Brush
290
$280
14. Polntlllst Blue
1993
Ilmenite Glaze
375
$280
15. Iron Landscape
1993
Iron Oxide
340
$290
16. Hanko
1993
Basalt Glaze
17. 1 Hear the Creek Falling
1993
Cobalt Glaze
320
375
$300
18. Heraldic Pelican
1993
Blue and White
395
$300
$300
19. D a w n
1993
Grey Glaze
405
$300
20. Marine Sunset
1993
Copper Glaze
410
$300
...2/
Gallery Hours: Tuet - Saturday 1:00pm - 6:00pm
Mornings by appointment
118 Sutherland Street, Paddington N S W 2021
Phone: (02) 326 2122 Fax: (02) 327 8148
BLOOMFIELD GALLERIES
D7AN ENGLUND
Page 2
TITLE
DATE
GLAZE
SIZE (mm)
320
PRICE
21.
Windblown
1993
Wax Resist and Blue
22.
Winter Landscape
1993
Wax Resist and Blue
320
$375
23.
Afterglow 2
1993
Copper Variations
340
$375
24.
Trees and Hills
1993
Blue and White
360
$375
$375
25.
Evening Sky
1993
Red Copper
310
$380
26.
Southeaster
1993
Wax Resist and Blue
315
$380
27.
May 5th
1993
Cobalt and Copper
320
$380
28.
Wedding Dat
1993
Copper Speckle
370
$380
29.
Afterglow 1
1993
Copper Variations
410
$380
30.
Blue Group
1993
Blue and White
445
$380
31.
Gala
1993
Matt Glaze
460
$390
32. Towards Ebor
1993
Celadon Glaze
385
$400
33.
Tablelands Landscape
1993
With Blue Oxides
415
$400
34.
Looking South
1993
Cobalt Painted
440
$400
35.
Blue Border
1993
Cobalt and Copper
470
$400
36.
New England Landscape
1993
Blue on White
495
$400
37.
The Blue Poplars
1993
White with Cobalt
480
$420
38.
Fire Shower
1993
Basalt Glaze
480
$450
39.
Valley Dawn
1993
Copper Glaze
485
$450
40.
Cool Valley
1993
Varied Copper Glaze
490
$450
Gallery Hours: Tues - Saturday 1:00pm - 6:00pm
Mornings by appointment
110 Sutherland Street, Paddington NSW 2021
Phone: (02) 326 2122 Fax: (02) 327 8148