Crystalline glazes are fascinating and frustrating. Successful crystalline glazes are the result of using a clay body with no grog or sand (ideally porcelain), so that the glaze can freely move.

The crystals in these glazes can be large and spectacular. Crystal shapes such as fans, circles, rods and stars may appear in various sizes seeming to float in a smooth background. The crystals are formed from a combination of zinc and silica, similar to the naturally occurring mineral willemite.

This glaze is very fluid which is necessary to form crystals. During the melting process the positive and negative ions are attracted and bond to each other. As the glaze continues to flow molecules are attracted and bond to form the crystals.

There are numerous things that affect the formation of crystals in a glaze the thickness of glaze application, firing time, shape of the pot, maximum firing temperature, soaking temperature and soaking time. Minimize this information.