(aluminum) (Al2O3) a refractory material that increases the viscosity of a glaze, making it less runny, and that helps to control the melting point to a glaze.  The main sources of alumina are china clay and ball clay.  Because of its high melting point, only a small amount of alumina is needed.  Alumina also helps make glazes more durable

(bisquit) Unglazed ceramic are that has been fired at a low temperature to remove all moisture from the clay body and to make handling easier during glazing.  Usually fired up to ∆08 to ∆06

(calcining) To heat a substance to a high temperature, but below its melting point, causing loss of moisture.

Objects made from earthy materials with the aid of heat; the process of making these objects.

A term usually applied to any white ware fired at a low porcelain temperature.  It was developed in Europe to compete with the expensive imported Chinese porcelain.

An opaque overglaze paint that is fired onto already-fired glazed ware at various low-range temperatures, usually 1175-1325ºF.  Because of the low firing temperatures, colors such as red and orange remain stable and do not burn out.  Sometimes called overglaze enamel or enamel.

A variety of earthy materials formed by the decomposition of granite.  In the process, these may have been combined with a variety of other materials, forming clay bodies with differing maturing points.

Clay found in nature that was formed in place rather than transported by the action of water.  Also called residual clay.  Kaolin is primary clay.

Natural clay that has been moved by water or wind from its source and settled elsewhere in deposits 

Material, such as sodium carbonate of sodium silicate, added to slip for casting to maintain its fluidity.  Less water is needed in a slip containing deflocculant; thus less shrinkage will occur in drying the cast object.  When spraying a glaze that is too viscous, add Darvan #7 to it to thin the solution.

Originally, the term referred to slip that is applied over the entire surface of an object to change the color and/or texture of the clay body.  The term now often refers to slip used for decoration

A combination of two or more ceramic materials whose melting point is always lower than that of any one of the materials used alone.

Any of a group of common rock-forming minerals containing silicates of aluminum, along with potassium, sodium, and calcium.  Used extensively in stoneware and porcelain bodies and in glazes as a flux.  Feldspars melt at a range of temperatures between 2192-2372˚F depending on their composition.

A substance that lowers the melting point of another substance.  Oxides such a s those of iron, sodium, potassium, calcium, zinc, lead, boron, and others that combine with the silica and other heat-resistant materials in a glaze, helping them to fuse.

A glaze material that is formed when any of several soluble materials and melted together with insoluble materials, cooled rapidly, splintered in cold water, and the ground into powder.  This renders them less soluble and less likely to release toxic material.  Feldspar is a natural frit.

An essential component of any glaze.  The main glass former is silica.

Any vitreous coating that has been melted onto a clay surface by the use of heat.  Made fine-ground minerals that, when fired to a certain temperature, fuse into a glassy coating.  Glazes may be matt of glossy, depending on their components.

The firing of clay and glazes in which the kiln temperature reached is usually in the ∆8 up to ∆10-12 (2316-2415˚F) range.  Ware fired in this range is usually considered to be stone ware.

A white-firing primary clay that withstands high temperatures but is not very plastic.  An essential ingredient in porcelain its presence in large quantities in China allowed the potters there to develop their fine white porcelain.