Ceramics Glossary

A highly plastic secondary clay used to add workability to clay bodies. Fires to a light color and is a key ingredient in many stoneware and porcelain recipes.

The initial firing of raw clay (greenware) to drive off water and organic matter, producing a hard but porous state suitable for glazing.

Polishing the surface of leather-hard clay with a smooth tool to create a low sheen without the use of glaze.

The fundamental first step in wheel throwing, in which the potter forces a lump of clay into a perfectly symmetrical, wobble-free form on the spinning wheel head.

A formulated mixture of clays, fluxes, and fillers designed to have specific working properties and fired characteristics.

A hand building technique using ropes of clay stacked and blended to form vessel walls.

A standardized indicator of heat work inside a kiln, combining the effects of temperature and duration of firing.

A glaze defect consisting of fine cracks caused by a mismatch in thermal expansion between glaze and clay body.

Low-fire ceramic that remains porous after firing, typically fired between 1000 and 1150 degrees Celsius.

A coating of colored slip applied to the surface of clay before or after bisque firing for decorative purposes.

A material that lowers the melting point of silica in glazes and clay bodies, promoting vitrification. Common fluxes include sodium, potassium, calcium, and lithium compounds.

A glassy coating applied to ceramic surfaces that melts during firing to form a smooth, often decorative, waterproof layer.

Unfired ceramic objects that are air-dried but have not yet been fired in a kiln.

Ground-up fired clay added to a clay body to reduce shrinkage, add texture, and improve thermal shock resistance.

A pure white primary clay mineral essential for making porcelain, with the chemical formula Al2Si2O5(OH)4.

A thermally insulated chamber used to fire ceramics at controlled temperatures.

The stage of drying when clay is firm enough to hold its shape but still damp enough to be carved, trimmed, or joined.

A high-fire, vitrified, white, and often translucent ceramic made from kaolin, feldspar, and silica.

A Japanese-origin firing technique involving rapid heating and removal of glowing-hot pots for post-firing reduction in combustible materials.

A kiln atmosphere with insufficient oxygen, causing carbon monoxide to strip oxygen from metal oxides and alter glaze colors.

A decorative technique of scratching through a layer of slip or underglaze to reveal contrasting clay beneath.

The process of fusing ceramic particles together at high temperatures without reaching the full melting point of the material.

A forming method in which liquid clay is poured into absorbent plaster molds to create uniform, often complex shapes.

A mid-to-high-fire ceramic that is dense and durable, partially to fully vitrified, fired between 1200 and 1300 degrees Celsius.

The progressive fusion of clay particles and formation of a glassy phase during firing, making the ceramic body dense and waterproof.