Alumina, calcined, 325 mesh (for glaze)

When used as a direct source of alumina in glazes, alumina has the effect of increasing glaze viscosity and firing range and resistance to crystallization.

The crawling tendency of glazes with high clay content is reduced by introducing alumina as part replacement for clay.
 
Calcined aluminas are generally used in porcelain and whiteware bodies.

A melting point of 2050C makes alumina useful in batt washes, etc.