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Thesis/Dissertation Collections
6-1-1976
Ash glazes, local slip glazes and once fire process
Howard Skinner
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ASH
GLAZES,
and
LOCAL SLIP GLAZES
ONCE FIRE PROCESS
BY
Howard Skinner
B.F.A.
Rochester Institute
June,
1976
of
Technology-
Preface
My
findings
have
which
development
techniques
surface
for writing this
reasons
steady line
glazes,
be
will
striving to join
into these
myself
natural
clay glazes
process
itself.
great
This
ash
savings
fire
once
glaze
clay by
a
one
of
the
step
with
the
to
Also
the
was
used
on
a
accessories.
closeness
of
the
fire
method
which
time-wise,
ash
by
a
and
clay-forming
joins
the
raw
from
raw
has
clay
and
raw
11.
in
resulted
slip clay
quality
clay to finished
process.
the
ecologically.
and
taking away the fresh
fired
glaze
stismlated
of
fire
the investigation has led toward
once
process
areas
and
my
into the
once
ash
to be
enough
relation
economically,
without
being
consistent
oriented
an
functional dinnerware
of
Investigation
development
of
present
explorations
local slip glazes,
the production
and
which
from my
resulted
ash
of
thesis is to
of
product
the
in
TABLE OF CONTENTS
I.
Preface
Page
1
II.
Introduction
Page
2
III.
Problem
1.
Location
2.
3.
Reasons for once fire technique
Treatment of slip readying for glaze
4.
Combining
5.
Kinds of wood ash
Ash glaze additions
Ash chemical analysis
Ash glaze colorants
Glaze applications
Once fire clay body considerations
Design elements for once fire
6.
7.
8.
9.
10.
11.
IV.
of natural
slips
and
glaze
slips
ashes
Page 3
Page 3
Page 5
Page
Page
Page
Page
Page
Page
Page
Page
6
6
7
8
9
13
14
15
Page 15
Conclusion
111,
ASH
GLAZES, LOCAL SLIP GLAZES
ONCE FIRE PROCESS
and
glaze
formulas
are
available
provided
in books
and
periodicals
Many
mation
companies.
glaze
formulate
should
instant
from
So why
my
own
else
to be
far
cupboard
a
glaze
used
removed
on
it down,
bag it,
which
glaze,
I have
glaze
no
which
can
be
slip
glaze
and
the
made
one
else
made
ash
so
my
and
surface
I may do
wood
screen
it,
own
ball
slip
glaze
to
glaze.
1.
comes
of
I
If
which
When I
mill
I
produce
want
ashes
can
I
dig
it, dry it,
base for my
to
use
united
another
from burned
also
still
my
individualized
the formed pottery is
glaze.
a
ready for
has been
spirit
glaze
when
commercially
created.
by using the
into
own
from the
do.
can
movement
which
my
are
pottery
of
one
slips
clay
particular
to the
go
reproduce
seem
slake
in
natural
own
commercial
to why
formulas
glaze
or
into the pottery that I have
This
way
I
and
someone
glazes.
a
glazes
making my
should
would
clay,
then
and
by
This
put
me
chemicals
developed
work?
unknown
with
as
It is transmitted through the
within.
prepared
have
To
use.
hands.
dealing
obtainable
proven
other
asked
glazes
from
and
The question may be
infor
from the
today
combine
another
the
type
of
2.
Ash
texture
would
can
which
sarily the
these glazes,
smooth
The
glazes
a
the
qualities
fully
developed
which
may be
of
will
in
potters.
Two
have described
slip
Rhodes
known
who
wrote
potter
produce
for
glaze
the
which
Rochester
introduced
Institute
me
to
introduction led
separately
with
other
varying
by
I
or
by
a
me
whose
and
glazes
ash
observed
of
combining
formulas when
surfaces
stemmed
pottery.
from
from personally
I have
once
used
are
read
and
and
One
summer
well
at
Technology is Frans Wildenhain.
consider
combining
It
textures
using
who
Daniel
Potter.
of
by
techniques
fire
my first
shore
both
use
production
and
the
for
textural
will
glaze
elements
and
during
slip from the
to
rough
and
dinner-
In
surface.
Pioneer Pottery
Glazes
and
rough
has
books
authors
chemicals.
surface
glaze
of
of
quality
elements
it
be
qualities
in making
use
neces
suit
These
consistent
not
to
surface
eating
varying
ware
my
accenting
from reading books
Clav
whom
an
glazes.
Michael Cardew who wrote
are
or
ash
in
ways
of
a
develop
either
the
to
applied
smooth
natural
gleaned
observing the
other
a
reproduced
Interest
information
use
against
played
inherant
to be
are
to
wish
developing
reflecting both
surface
variations
surface
In
gradation.
for example,
ware,
I
which
is
This
once.
steady textursil quality
a
rough
or
produced
ash
to have
considered
often
only be
case.
maintain
smooth
is
surface
glaze
He
lake Ontario.
natural
slips
and
This
ashes
them or
by
further combining them
led
me
in the direction
also
available
by using
them for textural effects.
slips
or
of
ash
th*
alone,
The
in
ways
of
purpose
which
efforts
my
glaze
natural
chemically to form
a
making it
for
possible
to be fired once
therefore,
and,
gas
glaze
which
would
a
has been to
elements
over a
applied
time
on
combined
thus
over
clay body
a
the bisque firing stage,
eliminate
down
cut
be
fire body?
once
to be
glaze
would
could
develop
and
seek
for
loading,
on
and
for firing.
used
When seeking the clay from
which
are
glazes
slip
one
made,
*
look for
must
spots
of
vein
clays
located.
are
road
construction
sides
can
be found
Usually
the
in
a
vein
of
be
will
organic
bank
whole
It
is
which
Another
in
drainage ditch beside
clay
when
found
of
stones
particles
of
clay to
observe
excavations
because
good
a
place
that
of
debris
settle
are
made
clay.
of
rest
the
of
sand,
there may be
can
and
a
be
look for slip clay is
to
cuts
good
thus,
glazes
from stones,
however,
which
road
is particularly
it free
washed
size
glazing.
for slip
free from debris
quite
through
cut
large bank
a
be found
also
may
used
fairly free
Sometimes,
for slip
This
be
will
debris.
clay
They
different from the
color
a
used
a
in
the
found along
it necessary to
made
noticeable vein
clay in the bank.
other
has
banks.
The best clay to be
hills.
of
river
visible
most
large clay
where
These banks may be
lakes or along
the
in banks
are
The
clay.
sedimentary
of
shores
anf
of
sedimentary
deposits
where
a
though
a
bank.
because nature has
leaving
in the ditch.
for house
the
smaller
It is
well
to
foundations
clay deposits may be found below the topsoil.
After
4.
the
slip clay has been located
be
clay down.
the
slake
through a
run
dug, it is necessary to
and
to
thirty
The
to ball
the clay
into
ground
the
a
of
for
glaze
testing in
The
firing
the
ranges
the
to
a
or
feldspar,
a
or
The
ash.
will
contribute
it
can
streaks
of
the
of
wood
that
ash
tend
could
to the
result
of
the
of
slip into
firing
after
range.
may vary widely
After
clay.
a
make
are
finish
mat
flint silica,
added
frit to
or
syenite,
is
totally
firing
glazes
finish may be
mat
results
often
added
which
chemical
will
ash
kind
the
are
may vary from
surface
slip
to apply the slip
slip/s
composition
the
a
a
more
glassy surface,
it may be done by adding kaolin
zirkopax.
ash
wood
or
slip
is desired,
surface
of
natural
If the
Another flux
amount
these
or nepheline
pax
super
the
glaze
To
surface.
mat
to find
should
process
the
makes
time
order
chemical
slip
high gloss.
glassy
or
of
particles
This
Now it is
size.
the
upon
firing,
and
equal
step in the
next
creamy consistancy.
particles
depending
until
slip
to free
screen
mesh
sixty
from any remaining debris.
mill
it
After the clay becomes slurry,
add
in
the
of
surface
a
on
it
a
will
be
change
Fruit-wood
a
it
with
surface
found
can
be
made
glassy,
are
running
texture.
In the
glaze
such
hue
which
choice
that the different kinds
in the
yellow-brown
hue
varying the
By
there
is
glaze
slip
yellow
glaze
which
ash
a
slip.
the
to the slip,
make
content.
to give
carries
color
to the
added
beauty to the
ash,
will
be
to
as
color
apple,
the
and
the
for example,
glaze.
Hard-wood
5.
ash,
it
will
wood
ash
consists
to seventy
thirty
when
This is
caused
magnesia.
the
glaze
be
lime,
The
and
make
the
so
doing
a
mat
or
better
to
eight
cone
The
ash
the
firing
the
up to
potash,
phosphorous
to further flux
altered
to the
thirty
Clay
surface
of
the
be controlled.
can
glaze
also
must
to which the fluxes have been
be
can
can
range
As
acquired.
be
adjusted
a
result
between
of
cone
eleven.
of
gloss
itself.
surface
of
up to
percent
form
will
content
chemical
whiting.
adhere
the fluidity
opaque
these additions,
may be
possibly
ash.
iron oxide,
of
flint or
adding kaolin to the glaze
added
and
ten
cone
alumina,
percent
surface
ash
the
by
traces
some
glaze
to
heated
up to fifteen
silica,
adding felspar,
By
pottery.
By
by
to
added
up to fifteen
percent
and
darker brown color
a
by itself
of
percent
give
iron than does the fruit-wood
more
glassy surface.
which
will
maple,
contain
Any
a
as
such
the
ash
Hard-wood
ash
may be varied
glazes
such
as
maple
is
by the
made
up
kind
of i
of
Si02-
14.08, Al203-3.69, Fe203-0.94, P205-2.l4, Ca0-35.90, Mg0-5.44,
MnO-0.14,
K20-1.45, Na20-0. 55.
This ash
wood
ash
into
a
ash
also
glaze
of
to the
a
has
different color hue.
gives
chemically is
a
a
yellow-green
made
up
of:
hue
glaze
Apple
color.
ash when
to the glaze.
The
Fruit-
mixed
apple
Si02-2.7, ^zO^-k^, CaO-70.9,
K20-11.8, Na20-1.9, SO3-2.7
MgO-5.5,
cast
dark green hue
gives
which
leads to
a
yellowish
color.
Some
other
sources
of
ash
are
soft-woods
(pine),
straw,
6.
grass
an
cuttings
ash
color
and
to
hue
a
bleaching
and
are
with
in the
oxides
to
these may be
slip
using
such
as
oxides
glazes,
spodumene
To
formula
one
are
all
composed
produce
individual
an
certain
color
changes
slip,
Barnard
slip,
I
chose
crystal
to
produce
cobalt
glazes,
in
or
weret
and
oxides
flux,
a
iron,
a
cobalt
color
added
along
glazes.
Some
any
The
slip clay.
natural
art
slips
Most
produce
may be
Many
Albany
to
add^d
Most
glaze.
as
act
Rutile,
surface.
create
which
They may
may be
which
ash
oxides.
metalic
of
color additive.
a
oxides
glaze
to any
added
characteristic.
or as
red
rutile
may be
colorants
agent,
copper
changes
of
than
more
produce
will
ash
of
will
substance
glaze.
these colorants
have
burnable
Any
every different kind
and
Additional
of
leaves.
other
formulas
glaze
iron
clay
saturate
manganese
glazes
and
glazes.
iron
produce
saturate
ash
bone
at
glaze
I
started
with
the
of:
70f
Red art
Apple ash 30$
To
this
quality
I
next
and
to
added
add
formula next add
oxide
of
crystals
To
to be
produce
to
the
iron
work
formed
rutile
Hard-wood ash
Kingman feldspar
5% to induce
flux.
additional
percentages
to increase
iron I found
ash
best
in the
the glaze.
of
This addition
saturate
glaze.
crystal
glaze
35f
35$
glaze
to five percent iron
5%$ causing iron
at
opalescent
To this working
from two
content
an
I
started
with:
7.
China
Talc
Clay
20$
15$
2$
2$
Rutile
Ilmenite
In my testing
wood
have been
ash
I have found
effective
been
added
been
used
as
as
than
a
and
silica
to
the
glaze
rutile
the
is
to
added
may form
rutile
tributes
titanium
yellowish
To
halo
for
give
source
the
rutile
and
ash
50$
30$
15$
Albany
slip
Cobalt
Manganese
Chrome oxide
To
produce
of
the
feldspar,
is
Apple
added
as
to
add
and
act
both
contribute
To
to
glaze
additional
The
added.
iron
to
oxide
tan to brown
coloring
of
Ilmenite
also
further
glaze.
This
contributes
and
con
a
crystals.
glaze.
I
started
with:
1$
1$
a
apple
ash
and
alumina,
primarily used
to
has
Clay
.05$
this glaze,
glaze.
in the
titanium
manganese
Custer feldspar
Apple
also
a
iron to the
cobalt
produce
gives
crystals.
around
The China
flux.
of
is
ash
Kingman Feldspar has
silica
added
hard-wood
a
crystals,
rutile
ilmenite have been
and
and
is
maple
and
ash
develop
former.
rutile
glaze
wood
ash.
additional
a
to
which
alumina,
in turn
This
glaze.
ash
glass
of
apple
trying
Talc has been
magnesia
color
both
fruit*wood
and
source
formers.
glass
maple
the
flux
a
In
tried.
that the
more
as
this formula,
of
provide
is
used
as
a
high
percentage
contains
some
flux
ash
and
iron
and
glass
additional
the
magnesia.
former.
flux
and
major
The
of
portion
potash
ash
is
Custer feldspar
glass
former.
The
8.
slip is
Albany
has
both
added
high iron content
a
colorant
cobalt
contributes
hue is
formula
chrome
Cobalt oxide
Manganese
Iron oxide
crystals
in the
contains
lithium
glaze
spodwiiene
.1$
1$
mixture.
as
a
to
added
glaze
healer.
and
possibilities
colorant
which
glazes,
to apply
ash
glazes
to easily
clay
will
was
The
first consideration
or
powder
glazing
body
formula
for the
once
as
cause
flake
they
flaking.
the
glazes
are
The
still
combination
to
a
another
once
is that the
are
applied
third
not
problem
fire, green,
glaze
the clay surface.
off
fire ware,
when
use
oxides.
ash
It
The
and
1$
10$
1$
20$
After formulating the
me.
feldspar
of
20$
few color
clay body.
also
form
iron
15$
Lithium carb.
Barium carb.
the
a
the
out
30$
25$
20$
Zercopax
ashes
is
bring
is:
Iron
a
to
glaze
surface
Spodumene
Dolomite
Kaolin
are
a
This
Apple ash
Custer feldspar
when
manganese
.5$
may be
Spodumene
faced
greenish
30$
15$
Albany slip
wood
A
glaze.
a
manganese
colorant
cobalt
As
color.
ash
Custer feldspar
of
The
oxide.
The
the
to
color
the
to
It
forming.
glass
is:
Apple
These
blue.
color
blue-purple
by the
caused
the
for
and
clay
contributes
which
provides
deep
a
a
as
Secondly,
pulled
to bisque
consideration
tends
as
ware.
deep into
This
is to prevent
9.
stress
cracks
To
When applying
higher may be
or
from cracking
The
of
the
side
one
of
piece
then
surface
or
spraying
then
stress
By
order
using the
the
same
is desired,
surface
opposite
side
by glazing both
sides
is
to be
which
once
fire
ones
am
with
strong
formulate
This
such
slips
green
ware
a
good
once
is
special
Flint silica
AP Green fire clay
Custer feldspar
be
low
used
once
of
I have and
of
clays
fire body.
composed
for
percentage
strength.
30$
15$
5$
30$
3 to 5$
5 to 8$
as
may be applied.
body to
stoneware
EPK
Kyantitsue
Grog
glazed.
methods
high plasticity,
presently working
A9 White
to be
technique, glazing
clay
I
by
applied
putting
for the
can
If glazing only
may be
not
one
without
Considerations
I
by glazing
of
water
experimenting with many different kinds
hope
of
percentage
glazed
and
and
mixture
glaze
surface
other.
which
resist,
in drying
a
the clay
stop the flat
to
time
glazing the
wax
are
the
off
clay.
double dipping,
firing
plates
prevented
the
at
piece
the
be
can
pottery
dunking
the
on
cracks
the
allow
in
needed
flaking
or
bentonite to
to flat
glaze
immediately
of
add
glazes.
flaking.
or
stress
and
will
from powdering
it is necessary to
3-5$
5-7$
form uneven
result
the glaze
keep
surface,
at
which
of:
The
from
am
shrinkage
still
which
clay body
I
with
10.
Some
way in
that
be
thicker
walls
is
glaze
The
opment
the
form
ash
which
glazes,
of
production
an
I have
techniques,
within
the
essence
spirit
and
form with the
line
of
be
sharp
alterations
angle
are
fire
stress
glaze
foot or
enough
glaze.
In
changes
or
leave
This
to be done.
the chances for *s tress cracks
able
to
production
have been described
oriented
and
of
ash
once
glaze
accessories.
relate
when
green
or
its form.
pottery.
a
to be
piece
of
the
pottery holds
By combining the
highly spirited,
used
developing
technical abilities which
produce
techniques
fire
surface
In
my devel
to draw myself closer to
tried
thrown
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and
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for functional dinnerware
these
glazing
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to
while
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upon
reflected
applied.
procedures
of
try
will
pieces
pieces
onto
where
thickness
extra
the
trimming
the form
to be
elements
the
upon
to hold
surface
developing
and
put
When
process.
the
to handle
which
will
some
the design
of
but
closeness
of
I have found,
yet
saleable
Ash Clays
1.
Iron
2.
Rutile
crystal
3.
Cobalt
and
4.
Spodumene
5.
Formal
6.
Closeup
saturate
Illustrations
glaze
glaze
manganese
glaze
glaze
dinnerwar^ placesetting using
of
double
dipping
glazes
ash
glazes
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