Pinch
Slip
Inlay
Carve
Pierce
Coil
Variety
Organic
Geometric
Repeating / Pattern
Slip
Score
Green
Leather Hard
Bone Dry
Pugged
Pugg Mill
Pin Tool
Loop Tool
Rib
Kidney
Chamois
Cutting Wire
Boxwood Tool
Extruder
Kiln
Bisque
Glaze
Wax Resist
Foot
Lip
Slab
Slab Roller
Fettling Knife
Blue Trimming Wheel
Bat
Canvas
Calipers
Pulling / Raising
Opening
Centering
Base
Walls
Slope
Right Angel
Parallel
Body
The bulk composition of a ceramic vessel,
Burnish (G&W)
The smooth, sometimes faceted effect on the surface of a vessel produced rubbing
leather-hard clay with a rounded tool. It can be done with a circular motion but more
commonly was done with short, linear strokes; some Romano-British vessels were
burnished on the wheel, producing long facets running all the way round the pot. The
process compacts the surface, slightly reducing permeability, and often imparts a high
shine; it is thus both functional and decorative. On occasions, mineral particles (for
example, graphite or hematite) were applied to the surfaces of leather-hard vessels and
burnished, the burnishing providing the most effective method of keeping the pigment in
position. It is sometimes called polish (U.S.), but this term is more correctly used to
describe a post-firing treatment of glazed wares. Water-worn pebbles are common
burnishing tools used by modern traditional potters but other materials, such as bone,
may also have been used.
Burnishing (S)
Finishing technique, rubbing leather-hard vessel with hard tool, such as a stone or
potsherd, to produce glossy surface, with irregular luster and polishing marks visible.
Coiling or coil-building (G&W)
Method of pot manufacture utilizing long ropes of clay. The potter winds the ropes of
clay round to form the desired vessel shape or part thereof and then joins them together
by smoothing the internal and external surfaces. This basic shape is then usually further
refined by thinning and expansion of the walls. It is generally almost impossible to
distinguish it from ring-building.
Coiling (S)
Hand-building technique, involves forming and joining narrow coils of clay to build up
vessel walls.
Drying shrinkage (G&W)
All clays shrink as they dry. After a pot has been made, it is left to dry before firing; the
water of plasticity evaporates from the surfaces of the vessel and the clay particles are
gradually brought into contact with one another. The finer the clay, the greater will be the
shrinkage on drying. Thin parts of a vessel obviously dry more quickly than thick parts,
creating stresses that cause cracks. The drying rate can be made more even and drying
shrinkage reduced by the addition of opening materials.
Firing (G&W)
The process whereby clay is converted to ceramic. A temperature in excess of 550° C is
required to drive off chemically combined water from the clay molecules and make them
ceramic; when this process has occurred, the clay will be hard and will not become
plastic when in contact with water.
Glaze (G&W)
Glazes are vitreous coatings consisting of a glass former (usually silica) with the addition
of a glass modifier, or flux, to lower its melting point. Typical modifiers are lead, sodium
and potassium. Color is achieved by the addition of metallic oxides, such as copper and
iron.
For example, early glazes on pottery in western Europe were lead-based and arrived with
the Romans. This type of glaze, which was again used in the medieval period, is easily
prepared by applying crushed lead sulphide or oxide to the surface of a leather-hard
vessel; during firing, the lead reacts with the silica present in the clay to form a glaze. In
thin section, glazes are transparent in plane polarized light, inactive under crossed polars,
and frequently exhibit highly rounded voids, a characteristic of molten material.
Glaze (S)
Composed of silica, fluxes, and metallic oxides, glaze becomes vitrified or glasslike
when fired at high temperatures.
Incised decoration (G&W)
A very common surface treatment used throughout prehistory and indeed later. It
involves dragging a sharp instrument through leather-hard clay. The technique can vary
considerably in sophistication and in the type of incisions made.
Inclusions (G&W)
The term used to describe all non-clay and/or non-plastic materials present in a clay body
or fired fabric. They may be naturally occurring or added by the potter. See also filler,
opening materials, or temper.
Inflection (S)
Point on vessel profile where vessel wall changes direction.
Kiln (G&W)
A structure for firing ceramics. Kiln are almost invariably associated with wheel-thrown
pottery, as the finer clay bodies required for that process contain few opening materials
and must therefore be fired slowly at first, so that the water of plasticity can be removed
gradually and thus prevent fire spalls and explosions. Kilns consist of a firebox, a flue, a
firing chamber, a dome (which may or may not be permanent) and an exhaust vent. The
raw clay vessels are placed in the firing chamber, thereby being separated from direct
contact with the flames from the fire.
In contrast to open firing, kiln firing utilizes hot gases rather than direct contact with the
flames to fire the pots. It is a much slower and less economical process, as much time and
fuel are expended in heating the kiln structure itself. However, the end products are
generally of higher quality, because finer bodies are used and higher temperatures may
(but were not always in antiquity) be reached.
Kiln (S)
Firing facility; fuel and vessels are placed in separate chambers linked by flues.
Leather-hard (G&W)
The stage reached in the drying of clay when most of the water of plasticity has
evaporated off, maximum shrinkage has occurred and the clay particles have come into
contact with each other. It is at this stage that most surface treatments and some
secondary manufacturing techniques, such as paddling, are executed, because the clay is
still moist enough to allow alteration. Also known as green-hard.
Leather-hard (Sh)
The condition of a clay body or paste when it has become firm but not dry. It is not a
state that is strictly defined, but clay workers judge it confidently from experience. A
vessel in the leather-hard state can be handled without risk of deformation because the
clay is no longer plastic and it can be carved of incised without chipping because it still
retains considerable moisture.
Leather-hard (S)
Clay that has dried to the point that it has lost most of its plasticity but is still soft enough
to be carved or altered.
Lip (S)
The edge of the vessel orifice.
Molds (S). Hand-building techniques using permanent forms into or over which clay is
impressed to shape vessels.
Neck (S)
Part of jar or restricted vessel between body and rim, marked by constriction and change
in orientation of vessel walls.
Pinching (S). Hand-building technique, involves forming vessel by opening clay ball and
pulling vessel walls up between fingers.
Pinch pottery (G&W)
The simplest method of pottery manufacture, involving the opening out and expanding of
a ball or cone of clay by squeezing the clay between the fingers, while the shape is
supported by and turned in the potter's hand. It tends to result in small, round-based, open
shapes (such as bowls), in which the method of manufacture can be recognized by the
indentations in the vessel walls left by the pressure of the potter's hands. It can, however,
be used as a preliminary method of manufacture, the shape so formed being added to later
by the addition of coils or rings of clay: present-day Gciriku potters in the Kavango
region of Namibia start all their vessels by forming the base in this way, adding flattened
rings, or straps, of clay and finishing the vessels by using a tool known as a rib. It has
generally been thought that pinch pottery was probably not used in antiquity or, if the
technique were employed, it was purely for the manufacture of small vessels, but this is
to deny the possible use of the technique as a preliminary method of manufacture, to be
supplemented by other methods, as in the African example give above; as with other less
immediately obvious methods of manufacture, it may have been missed because such
researchers have not known what to look for.
Plasticity (G&W)
The property of clay that allows it to be deformed by pressure and to retain the shape
created once the pressure has been removed. It is the result of water being present
between the clay particles, which allows them to glide over each other. The smaller the
clay minerals involved, the more water can be absorbed between the particles in a give
volume of clay; therefore, sedimentary clays, the particles of which have been physically
broken down by transport, are more plastic than residual clays.
Plasticity (S)
The ability of clay to be molded and maintain its shape.
Shrinkage (G&W)
Clay shrinks during drying and, at temperatures in excess of about 900° C, during firing.
During drying, shrinkage is a direct result of the amount of free water present and fine
clays will shrink more than coarse ones. The smaller the clay particles, the greater the
amount of water that can be absorbed between the particles to make the clay plastic, and
therefore the greater will be the shrinkage as the clay dries. Drying shrinkage can be
reduced by the addition of opening materials, which effectively take the place of clay in a
given volume. Less water will therefore be needed to produce a workable body and, as a
consequence, less shrinkage will occur as the clay dries. Drying shrinkage frequently
results in voids around opening materials.
Firing shrinkage occurs as the clay particles begin to melt at high temperatures. It rarely
occurs at temperatures below about 900° C; in contrast, most clays actually expand by
small amounts, becoming increasing porous during the early stages of firing up to about
800° C. Few vessels produced during prehistory are likely to have been affected by firing
shrinkage.
Slab building (S).
Hand-building technique which involves forming flat slabs of clay and connecting them
to form a vessel.
Slip (G&W)
Surface treatment involving the application of a suspension of clay in water to a vessel in
the leather-hard stage. It can be both decorative and functional: it is most usually
employed to change the color of a vessel but may also be used to reduce the permeability
of food and drinking vessels by partially sealing the surface. Slips are applied in a viscous
state by dipping, pouring or painting. They are not absorbed to any great extent by the
clay body and in thin section are easily distinguished as an optically inactive, separate
layer on the surface. Slip-trailing, a technique akin to icing a cake, was also used to build
up plastic features on the surface of a vessel or to add different colored slips.
Slip (S)
Liquid mixture of clay and water applied over surface of vessel to affect color and
texture.
Stonewares (S)
Ceramic vessels fired to temperatures of 1200-1350° C. Stonewares have partially
vitrified bodies, and most often are brown, gray or white.
Surface treatment (G&W)
Any decorative of functional method used to alter the surface of the vessel; examples
include: burnish, slip, glaze, incision, and cord-marking.
Terracotta (S).
Ceramic vessel fired to temperature of less than 900° centigrade, coarse and porous,
usually red.
Texture (Sh)
A property determined primarily by the particle size, shape, grading and arrangement of
particles. Surface texture is also influenced by finishing method. The expression apparent
texture is proposed for paste descriptions based on unaided visual inspection since the
finest grades cannot be seen and relative color contrast influences judgment. In defining
particle size by microscopic methods, the Wentworth grade scale is used.
Wheel-thrown (G&W)
The term used to describe vessels that have been made on the potter's wheel. Such vessels
are usually, though not always, flat-based. They can be recognized by the presence of
rilling as revealed in thin section and by X-radiography, and frequently, by the presence
of cheese-wire marks on the base. The term is not synonymous with wheel-turned, as
turning is a secondary process used to tidy up vessels in the leather-hard state; the two
processes are therefore quite different and require different terminology.
Writers in Britain frequently refer to slow wheels and fast wheels, the inference being
that the former is a simple, one-piece device, sometimes called a tournette or turntable,
and the latter the more sophisticated wheel with two parts (a flywheel and a wheel-head)
with which we, in the twentieth century, are all familiar. To make such a distinction in
terminology is clearly nonsensical: any type of wheel can be made to rotate either quickly
or slowly and, as long as sufficient speed has been obtained for centrifugal force to be
created, vessels can be spoken of wheel-thrown. It is worth noting that the highly
accomplished vessels of the Geometric, Archaic and Classical periods in Greece were all
thrown on what many modern writers would describe as a slow wheel.
*Wax Resist: A decorative technique where a wax based medium is used to create a
pattern, which is then covered, in another coat of glaze or slip. The wax resists the
subsequent coating creating the pattern. Paper stencils or tape can create a similar effect.
Latex is another effective resist with other advantages.
*Wedging: To kneed or mix plastic clay by hand. A hand process used to homogenize
the clay and remove air bubbles, thus making it workable. The techniques for wedging
are called; Spiral, or Chrysanthemum wedging, Rams head, or Monkey face wedging and
wire/slab wedging. Both Rams head and Spiral wedging involves the folding of the clay
on itself too build up an ever-tightening spiral of clay platelets. Wire wedging builds up
increasing layers of clay platelets and is the best for introducing other clays and fillers
into an already plastic clay body.
*Throwing: To make pottery by hand on the potters wheel. A delicate balance, which
defies gravity and centrifugal force as clay is coaxed up by hand from a spinning
turntable.
*Trimming, or Turning: Certain forms made on the potter’s wheel will not support
themselves unless excess clay is left at the base, alternatively, extra definition on the foot
of a pot may be needed. The solution to both these problems is turning, which is done at
the leather hard stage. The pot is inverted onto a potter’s wheel and a metal cutting tool is
applied to the bottom of the pot until the desired finish is achieved.
Underglaze: Ceramic colors combined with clay applied under a glaze, usually a clear
glaze. Although a durable method of decorating, colors can run especially if colorants,
which double as fluxes, are used, however more dependable than overglaze stains.
BISQUE WARE: Clay objects that have been fired for the first time and without
any glaze applied to them.
BONE DRY: Clay that is completely dried but not yet fired.
CERAMIC: Having to do with clay or glass or the making of objects from clay or
glass.
CLAY: The American Ceramic Society has defined clay as "a fine-grained rock
which, when suitably crushed and pulverized, becomes plastic when wet, leatherhard when dried and on firing is converted to a permanent rock-like mass." In
general, clay is considered to be hydrated aluminum silicate and can be
represented by the general formula Al2O32SiO22H2
COIL: rope-like form of clay.
EARTHENWARE / TERRACOTTA: A lowfired form of pottery or objects (below
1100oC, 2012oF) made from fire clay, which is porous and permeable. The clay
can be any color although iron red is usually associated with Terracotta. The low
temperature vastly expands the range of glaze colors available these are often
alkaline or lead based
FETTLING KNIFE: A special knife-like tool with a fairly flexible blade for cutting into
moist and leather-hard clay.
FIRING: The process by which clay is heated in a kiln and converted to ceramic.
FOOTING: the bottom of a clay piece that rests upon a surface (may be hand-built or
wheel-thrown). There are two kinds of footing: raised and flush.
GREENWARE: A term used to describe unfired clay objects in general.
GLAZE: A chemical mixture composed of silica, fluxes, and metallic oxides, most often
with added colorants, that when applied in liquid form to bisque ware, and fired at high
temperatures in a kiln, becomes glasslike, forming an appealing, often glossy, coating to
the surface of the clay.
GLAZE WARE: bisque ware that has been glazed, then fired.
INCISING: A common decoration technique created by carving lines into the surface of
leather-hard clay or carving small areas out of the clay but not perforating it.
KILN: A furnace for firing ceramics. A kiln is specifically designed to heat clay to the
high temperatures necessary to make it permanently hard and stone like.
LEATHER HARD: A stage in the drying process of clay when the clay is pliable but
strong enough to handle. It is ideal for trimming and the addition of appendages such as
handles and spouts. Relatively wet clay can be attached to the pot at this stage and the
resulting bond will not form cracks.
LOOP TOOL: A special tool with a wooden handle and a wire loop at one or both ends,
used for carving and hollowing out clay forms.
MOLDS: Hand-building techniques using permanent forms into or over which clay is
impressed to shape vessels.
PINCHING: A method of forming clay, which is well described by its name.
PINCH POTTERY: The simplest method of pottery manufacture, involving the opening
out and expanding of a ball or cone of clay by squeezing the clay between the fingers,
while the shape is supported by and turned in the potter's hand. It tends to result in small,
round-based, open shapes (such as bowls), in which the method of manufacture can be
recognized by the indentations in the vessel walls left by the pressure of the potter's
hands. It can, however, be used as a preliminary method of manufacture, the shape so
formed being added to later by the addition of coils or rings of clay
PLASTICITY: The ability of clay to be molded and maintain its shape. It is the result of
water being present between the clay particles, which allows them to glide over each
other. The smaller the clay minerals involved, the more water can be absorbed between
the particles in a give volume of clay. Some types of clay are more plastic than others.
SCORE: to draw or make lines into clay.
SLAB: a flattened out piece of clay; you may use a rolling pin or slab roller to achieve a
slab of clay.
SLAB BUILDING: Hand-building technique which involves forming flat slabs of clay
and connecting them to form a vessel.
SLIP: clay that has been watered down; acts similar to a glue in slip/score technique.
SLIP/SCORE TECHNIQUE: method used in hand building to connect two pieces of
clay together.
SPRIGGING-ON: A term used to describe the technique of adding small clay forms as
decoration on the surface of pottery forms; also called applied decoration.
STONEWARE: Highly vitrified ceramics fired to above 1200oC, 2192 oF. Most of the
silica in a fired stoneware body is melted into a glassy matrix and the resulting body is of
high density and usually has a water absorption rate of less than 1%.
THROWING: To make pottery by hand on the potters wheel. A delicate balance, which
defies gravity and centrifugal force as clay is coaxed up by hand from a spinning
turntable.
TRIMMING, or TURNING: Certain forms made on the potter’s wheel will not
support themselves unless excess clay is left at the base, alternatively, extra definition on
the foot of a pot may be needed. The solution to both these problems is turning, which is
done at the leather hard stage. The pot is inverted onto a potter’s wheel and a metal
cutting tool is applied to the bottom of the pot until the desired finish is achieved.
UNDERGLAZE: Ceramic colors combined with clay applied under a glaze, usually a
clear glaze. Although a durable method of decorating, colors can run especially if
colorants, which double as fluxes, are used, however more dependable than overglaze
stains.
WEDGING: The process of kneading the clay so as to remove air bubbles and create
uniform consistency of clay making it workable.
WHEEL-THROWN: The term used to describe vessels that have been made on the
potter's wheel. Such vessels are usually, though not always, flat-based.
Handbuilding Terms
Handbuilding This term refers to the one of several techniques of
building pots using the only the hands and simple tools rather than
the potters wheel. The term used for creating pottery using the
potter's wheel is "throwing".
Pinch "Pinch" in ceramics is a method of shaping clay by inserting
the thumb of one hand into the clay and lightly pinching with the
thumb and fingers while slowly rotating the ball in the palm of the
other hand. [See resources for links to tutorials on how to create.
See the Assignment 2 page for examples of pinch pots.] Pots made
in this manner are called "pinch pots".
Coil This is the technique of building ceramic forms by rolling out
coils, or ropes, of clay and joining them together with the fingers
or a tool. (How to do this can be found at
http://www.jhpottery.com/tutorial/coil.htm and
http://www.jhpottery.com/tutorial/scoil.htm.
Slip Slip is liquid clay. The easiest way to make slip is to
gradually sift or spoon dry, powder clay into a small cup of water.
Stir well as you add because it will tend to thicken up after it sits
for a minute or two. You want it to be about the consistency of
thick cream.
Score and Slip Score and slip refers to a method of joining two
pieces of clay together. First, score the clay; this means that you
make scratches in the surfaces that will be sticking together. Then
you slip it; that is you wet the surface with some slip, using it like
glue. Next, you press the two pieces together. It is very important
to always score and slip clay that is leather hard. If you do not, the
pieces will likely pop apart when they are fired.
Molding In this technique, flat slabs of clay are pressed into molds
in order to create various shapes or forms.
Stages of Dryness When speaking of clay, we refer to three basic
stages of dryness: wet, leather hard and bone dry. They are selfexplanatory, but descriptions of each can be found here.
Decorative Techniques and Terms
Sgraffito Sgraffito is a decorating technique developed centuries
ago. In its simplest embodiment, leather-hard clay is coated with
an engobe or slip of contrasting color and then a pattern or picture
is added by carving through or scraping off the slip to reveal the
clay underneath. Example of an Asian jar decorated with sgraffito.
Example of Mexican ceramics decorated with sgraffito.
Wax Resist In this decorative technique, patterns or designs are
created by brushing a wax medium over an area of clay, slip, or
glaze to resist the final glaze application when the wax is dry.
Slip Trailing Slip trailing is another decoration method. Slip (a
liquid clay) is applied to the greenware through a tube or nozzle,
much like icing a cake. See a demonstration here. Example of a
casserole dish decorated with slip trailing.
Stamping This is the technique of pressing forms into the clay to
get decorative effects. Examples of shell stamped Early Native
American pottery.
Majolica Below is the definition from encyclopedia.com
(mejol´ike, meyol´-)or maiolica [from Majorca ], type of faience
usually associated with wares produced in Spain, Italy, and
Mexico. The process of making majolica consists of first firing a
piece of earthenware, then applying a tin enamel that upon drying
forms a white opaque porous surface. A design is then painted on
and a transparent glaze applied. Finally the piece is fired again.
This type of ware was produced in the ancient Middle East by the
Babylonians, and the method remained continuously in use. It was
extensively employed by the Hispano-Moresque potters of the 14th
cent. By the mid-15th cent. majolica was popular in Italy, where it
became justly famous through the decorations of the Della Robbia
family. The method is still widely used in folk art.
Bibliography: See G. Liverani, Five Centuries of Italian Majolica
(tr. 1960); M. Barnes and R. May, Mexican Majolica in Northern
New Spain (1980).
Examples of Majolica roosters.
Mille Fiore This refers to a method of creating designs by folding
different colored clays together into "rods" or bars, then slicing
them as if you were slicing rolled cookies. This duplicates a design
over and over for each slice. Here is an example of glass beads
made in this manner and another explanation and example using
polymer clays here.
Firing Processes and Terms Dealing with Firing
Firing This is the process of heating the pottery to a specific
temperature in order to bring about a particular change in the clay
or the surface.
Bisque The term bisque refers to ceramic ware that has been fired
once without glaze.
Greenware This refers to ceramic ware that has not been fired.
Glaze A glass-like surface coating for ceramics that is used to
decorate and seal the pores of the fired clay.
Reduction
A kiln firing in which there is insufficient oxygen to consume the
free carbon emanating from the heated glaze and clay, resulting in
the formation of carbon monoxide. Oxygen-starved carbon
monoxide pulls oxygen from the clay body and glaze, forming
color changes in the coloring oxides.
Oxidation A kiln firing with a full supply of oxygen (as opposed
to a reduction firing). Electric kilns are this type.
Raku Raku is a method of firing pottery that takes a ceramic piece
in its raw state, greenware, and quickly (in 45 minutes to an hour
rather than 8 to 18 hours) takes the temperature up to almost 2000
degrees. Examples and explanations:
http://members.shaw.ca/daniel51/artstudio/raku.htm
www.guild.com (Search for "raku".)
The Japanese Connection Glossary
Parts of a Vase
Note: The parts of a vase correspond to the parts of a human body.
Check it out here:
http://www.joslyn.org/teach/packets/pots/define.html
Mouth The opening at the top of a vase.
Neck The (usually) narrower part that leads from the body of the
vase to the mouth.
Body This is the main part of the vase. It is usually the largest part.
Foot This is the part of the vase that meets the floor.