Glaze

A glaze is a thin coating of glass fused to a clay surface. A glaze is generally considered to be a thin, glassy coating fused to the surface of a clay form in the firing process.

This coating may provide: decorative effects...color, texture, opacity etc. functional qualities...hygienic surfaces, strengthened clay body etc.

A normal glaze mix can be represented theoretically as: Flux(es) + Stabilizer(s) + Glass Former(s) Fluxes: lower the melting range of the mix. Stabilizer: increase the viscosity and widen the melting range. Glass former: forms the glass.

Glazes are made by mixing raw materials available in the environment or from commercial suppliers. The glaze recipe is a list of raw materials which are chosen to supply the fluxes, stabilizers and glass formers necessary to make the glaze. Raw materials are complex or simple chemical structures of elements which, when heated during the firing, form or release oxides which combine with other oxides to make the glass or glaze. A fired glaze (glass) consists of a complex structure (matrix) of a number of oxides.Each glaze oxide can be classified in terms of the role it plays in the melt i.e. flux, stiffener, or glass former.

Some oxides commonly found in glazes are: Flux: potassium oxide sodium oxide lithium oxide calcium oxide magnesium oxide barium oxide zinc oxide lead oxide strontium oxide Stabilizer: Aluminum oxide Glass: Silicon oxide

Source: Glaze Teach, matrix2000.co.nz