Pottery Glossary
New to pottery or brushing up on your ceramics knowledge? This glossary explains common pottery, clay, glaze, kiln and firing terms in simple language to help you feel more confident in the studio.
A
Absorption
The amount of water a fired clay body can absorb. Lower absorption usually means the clay has become more vitrified and less porous.
Alumina
A key ceramic material that helps stiffen glaze, improves durability and affects how a glaze melts and flows during firing.
B
Banding Wheel
A rotating platform used for decorating, carving, trimming or applying glaze evenly around a piece.
Bisque / Biscuit Firing
The first firing of clay. It turns greenware into a stronger, porous ceramic piece that is ready to glaze.
Blistering
Bubbles or raised areas that appear on a glaze surface after firing, usually caused by gases escaping during the melt.
Bone Dry
Clay that has completely dried before firing. Bone dry clay is very fragile and contains no visible moisture.
Burnishing
Polishing leather-hard clay with a smooth tool or the back of a spoon to compact the surface and create a sheen.
C
Clay Body
A prepared clay mixture designed for a particular forming method, firing temperature, colour, texture or purpose.
Coiling
A hand-building technique where long rolls of clay are stacked and joined to create a form.
Cone
A pyrometric cone measures heat-work in a kiln. It helps indicate when the correct firing temperature and time have been reached.
Crawling
A glaze fault where the glaze pulls away from the clay surface during firing, leaving bare patches. Often caused by dust, oils or overly thick glaze application.
Crazing
Fine crack lines in a glaze surface, usually caused by a mismatch between the clay body and glaze during cooling.
D
Dipping Glaze
A glaze mixed for dipping pottery pieces into the glaze bucket, often used for quick and even application.
Dry Foot
The unglazed base of a pot. This prevents glaze from sticking the piece to the kiln shelf during firing.
Dunting
Cracking caused by thermal shock when a kiln is heated or cooled too quickly. Most common around quartz inversion temperature.
E
Earthenware
A low-fire clay body that remains more porous after firing. It is often used for terracotta, decorative ware and low-fire glazing.
Engobe
A coloured clay slip applied to leather-hard or dry clay for surface decoration.
F
Feldspar
A naturally occurring mineral commonly used as a flux in both clay bodies and glazes. It helps promote melting and contributes to a glaze's finished surface.
Firing
The process of heating clay and glaze in a kiln to transform them into ceramic material.
Flux
A material that helps lower the melting point of glaze ingredients, allowing the glaze to mature during firing.
Food Safe
A term used for finished ceramic surfaces considered suitable for contact with food when correctly fired and used as intended.
Frit
A pre-melted and ground glaze material. Frits are used to make certain glaze ingredients safer to handle and more stable during firing.
G
Glaze
A glass-forming coating applied to ceramic ware. It can add colour, texture, decoration and surface protection.
Glaze Fit
The compatibility between a glaze and clay body. Poor glaze fit can cause crazing, shivering or other defects.
Greenware
Unfired clay work. Greenware can be soft, leather-hard, dry or bone dry before bisque firing.
Grog
Pre-fired clay particles added to clay bodies to improve strength, reduce shrinkage and add texture.
H
Hand Building
Creating pottery without a wheel, using techniques such as pinching, coiling, slab building and sculpting.
Heat Work
The combined effect of temperature and time inside a kiln. Two firings can reach the same peak temperature but produce different results depending on how long heat is held.
High Fire
A firing range commonly used for stoneware and porcelain, producing strong, vitrified ceramic ware.
K
Kaolin
A pure, white-burning primary clay and key ingredient in porcelain. It is also used in glazes to add alumina and improve suspension.
Kidney
A smooth, flexible tool — usually rubber or metal — used for shaping, smoothing and compressing clay on the wheel or by hand.
Kiln
A specialised furnace used to fire clay and glaze at controlled temperatures.
Kiln Furniture
The shelves, posts and props used inside a kiln to support and stack work during firing.
Kiln Wash
A protective coating applied to kiln shelves to help prevent glaze from sticking permanently to the shelf.
L
Leather Hard
A stage where clay has firmed up but still contains moisture. It is ideal for trimming, carving and attaching handles.
Low Fire
A lower firing temperature range often used for earthenware clay and bright decorative glazes.
M
Maturing Temperature
The temperature range where a clay or glaze reaches its intended strength, surface and fired result.
Mid Fire
A popular firing range for many studio potters, often around Cone 5–6. Most Decopot clay bodies (Primo and PrimoPro) and Abbots glazes are used in this range.
O
Oxidation Firing
A firing atmosphere with enough oxygen, commonly used in electric kilns.
Overglaze
Decoration applied over an already glazed and fired surface, often requiring an additional lower-temperature firing.
P
Pinch Pot
A simple hand-building method where a ball of clay is shaped by pinching with the fingers.
Pinholes / Pinholing
Small holes in the glaze surface after firing, often caused by gases escaping through the glaze during melting.
Plasticity
The workability of clay. Highly plastic clay is easier to shape, stretch and form without cracking.
Porcelain
A fine, often white clay body known for its smooth surface, strength and sometimes translucency when fired thinly.
R
Raku
A fast-firing ceramic process where pieces are removed from the kiln while hot and often placed into combustible material.
Reduction Firing
A firing atmosphere with limited oxygen, often used in fuel-burning kilns to create distinctive clay and glaze effects.
Rib
A shaping tool used on the wheel or for slab work to refine, smooth and compress clay surfaces.
S
Saggar
A protective container placed inside a kiln to shield work from direct flame or to contain materials used for atmospheric effects.
Sgraffito
A decorative technique where a layer of slip or glaze is scratched through to reveal the clay body beneath.
Shivering
A glaze fault where small pieces of glaze flake off the clay body, usually caused by poor glaze fit.
Shrinkage
The reduction in size as clay dries and fires. Different clay bodies shrink at different rates.
Silica
A core ingredient in both clay bodies and glazes. In glazes, silica forms the glass structure and affects durability and surface quality.
Slab Building
A hand-building technique using flat sheets of clay to construct forms.
Slip
Liquid clay used for joining pieces, casting, decorating or surface treatment.
Soaking
Holding a kiln at its peak temperature for a period of time to allow heat to even out and glaze or clay to fully mature.
Stoneware
A durable clay body fired to mid or high temperatures. It is commonly used for functional pottery.
T
Throwing
The process of forming clay on a potter's wheel.
Trimming
Removing excess clay from a leather-hard piece, often to shape the foot ring or refine the form.
U
Underglaze
A coloured decoration product applied before glazing. It is commonly used for painting, drawing and detailed ceramic design.
V
Vitrification
The process where clay becomes dense, strong and less porous during firing.
W
Wax Resist
A wax coating used to prevent glaze from sticking to certain areas, such as the base of a pot or decorative sections.
Wedging
Kneading clay to remove air pockets, even out moisture and prepare it for use.
Wheel Throwing
Shaping clay on a rotating potter's wheel to create bowls, cups, vases and other forms.