Pottery Glossary


A simple inner skeleton usually made of metal, wire or wood, to support exterior material such as modeling clay, clay bodies, paper mache, plaster, etc.


A round, flat disc used for a base to throw clay using a pottery wheel. May be made of plaster, wood or plywood.


Biscuit or bisque firing – initial firing usually to allow the ware to be decorated before the second firing.

Bone China

Ware to which bone ash has been added. It fires at a lower temperature than true porcelain and is used to make mass-produced fine white china.

Bone Dry

Unfired clay which is warm (not cool or damp), dry, and dusty/chalky in feel. Ceramic ware needs to be bone dry prior to buique firing whereby the physical (free) water has evaporated.


The surface polishing seals the outside of the vessel and makes it smooth to touch. This is usually achieved with a hard river pebble or metal spoon.


Method of building an object by pouring a fluid material into a mold and then it sets up/becomes hard. The mold is removed and the object holds that shape. Materials used may be plaster, clay slips, bronze, waxes, rubbers, resins and other synthetics.


The process for taking a ball of clay and making it perfectly round in the center of a pottery wheel before proceeding to make it into a vessel.


To construct pottery or sculpture by rolling out clay in thin ropes to build a form.


An image, pattern or drawing created with ceramic oxides on a paper, (usually a commercial process) designed to be transferred onto previously glaze fired ceramics and then fired to a very low temperature around cone 020.


Clay bodies fired at temperatures below cone 1 (2110° F) that remain somewhat porous and open in structure. The vast majority of the world's pottery has been earthenware because of the wide prevalence of earthenware clays and the relative ease of reaching the kiln temperature necessary to mature the claybody. Two examples are terra cotta and whiteware (sometimes referred to as talc body).


A type slip or underglaze. It is a type of slip that when fired is vitreous or in maturation is halfway between a glaze and a clay. It may be white or colored, and is usually applied to high firing stonewares and porcelains at the green or bisque state.


A ceramic oxide or mineral that is added to a glaze, claybody or underglaze to lower the maturing (or melting) temperature. In the proper proportion and at the appropriate temperature, fluxes enable silica and alumina to melt and form a glaze. Flux sources include feldspars, barium oxide, bone ash, calcium carbonate, cryolite, dolomite, lead carbonate, lithium carbonate, magnesium carbonate, potassium carbonate, sodium carbonate, spodumene, talc, wollastonite, and more.


a material used in making glazes. Ground glass or glaze usually produced, frequently used, and formulated to render raw chemicals insoluble or non-toxic.


Refers to any state of raw/unfired clay. Including wet, leatherhard, and dry/bone dry.


A gritty, sandlike substance. Grog is added to claybodies for strength, texture and/or tooth. It reduces cracking and warping. It is made from grinding up fired clay.


A stage in the drying process of clay when it becomes stiff but still flexible, but is still damp enough to be joined to other pieces. The name is akin to the description of shoe leather and clay at this stage may also be carved, incised, engraved, planed, and trimmed/turned. It can also be said that its consistency is similar to hard cheese.

Luster or lustre

usually an iridescent, pearly or metallic glaze surface effect created by painting an application of a metallic solution onto previously glaze fired ceramics and then firing at a very low temperature around cone 020.


the optimum fired condition/potential or temperature of a fusion of glaze and/or clay when it achieves maximum hardness and nonporosity.


In our studio, refers to the technique of applying pigment over a raw glaze - one example of this technique is majolica. Otherwise it also refers to very low temperature (up to cone 013) paints, pigments, or metallic salts applied on top of a fired glaze such as china paints, enamels, decals, and lusters/lustres.

Oxidation Firing

A kiln atmosphere in which the presence of oxygen is sufficient in quantity to cause combustion of carbon gases. An electric kiln has a normal oxidation atmosphere. Fuel fired kilns can also fire in oxidation providing there is adequate air intake and the atmosphere remains clear.


A general term used to casually discuss raw ceramic materials, whether oxides or carbonates. A few examples: zinc oxide, red iron oxide, lead oxide, and for carbonates like magnesium carbonate, potassium carbonate. Oxides are used in formulating glazes, clays and for coloring glazes and clays.


A characteristic typical of unfired clay when it is moist, soft, pliable, and capable of being formed, manipulated, or easily molded, and still maintains its shape without cracking or sagging.

Pyrometric Cone

heat indicators in the form of sticks/bars or elongated pyramids of ceramic materials which deform/bend at a given temperature range with time enabling the potter to determine when the firing is complete.


A term in Western terminology taken from Japanese method and altered. A low temperature firing technique usually below cone 06 involving a very rapid firing cycle, removal of ware with tongs from a red-hot kiln, normally post-reducing the ware in a fireproof container with dry organic combustibles for a variable short amount of time, and removal again with tongs and quenching to prevent re-oxidation.


A decoration method where a substance such as wax, shellac, newspaper, tape or many other things are applied to a clay surface to keep glazes and slips from adhering.


Making scratches, usually in a cross-hatch pattern, with a knife, needle or serrated tool and using slip, to help make two pieces (coils, slabs, handles, etc.) of clay adhere to each other.


In ceramics, a tecnique where clay is coated with a colored slip which is carved through to expose the clay. Actually, any coating that is scratched through to expose the background.


The progressive lessening or contraction of clay in measureable dimensions and volume during both drying and firing. Different types of clay shrink at different rates, usually ranging from 6-14%.

Slake (slaking)

A process where clean, dry clay is covered with water to return it to a wet, usable state. Also the breaking down of other ceramic materials in water (soaking) with the end product usually being slurry.


Clay that is mixed with enough water to be as fluid as cream or as thick as yogurt. Uncolored slip is used to attach together unfired and moist clay pieces to create functional and non-functional art. Colored slip has ceramic coloring oxides added and is used to decorate. Other liquids similar to colored slip are underglaze and engobe. These can be commercially manufactured or made by hand.

Trimming or Turning

The final action in the throwing process. A leatherhard wheel thrown form is inverted onto the potter's wheel head and a foot ring is carved into the bottom or base of the form utilizing specialized tools and also to remove excess clay.


Usually refers to pigments, applied to raw or bisqued clay, that are normally covered with a glaze, such as commercial liquid underglazes like AMACO, chalks/crayons, and pencils. May also describe the technique of application of pigments such as washes.


The non running quality of a glaze during firing, a highly viscous glaze is stiff and does not flow much during the firing.


The hard glassy and nonabsorbent quality of a claybody and/or glaze when fired to maturity.

Wax/Wax resist

Melted paraffin or a synthetic wax solution. It is a liquid substance painted or dipped on ceramic art to resist water based liquids such as glazes, slips or stains. Wax is often applied to the entire bottom of ceramic art to help keep glaze from the bottom before firing.


A process by hand where clay is mixed, cut & slammed, and "kneaded" to eliminate air pockets, made smoother, denser and homogenous.