Clay glossary

A thin glassy layer formed on the surface of a ceramic article by the exposure of the glaze coated article to a high temperature. Glaze is usually applied in the form of a suspension of ground glaze in a liquid medium, to the clay or biscuit surface of the article.

Colouring agent added to a glaze.

The relationship between thermal expansion of body and glaze. Ideally the glaze should have a lower thermal expansion than the clay body, so that on contraction the body puts the glaze into compression. This avoids crazing of the glaze due to tensile stresses in it.

A surface that has been glazed. A body that has gone through both a biscuit and glaze firing.

Unfired clay ware.

Ceramic material which has been heated to a high temperature to burn off moisture and other gasses therefore is predominantly inert. This is then ground to a required grain size to add to a body formulation.