Controlled crystallisation in porcelain glazes

Abstract

Artistic crystalline glazes generally indicate heterogeneous surface crystallization. Therefore, it is not possible to control the location, amount and the size of possibly occurring crystals unless bulk crystallization is deliberately supplied. Conventionally produced porcelain crystal glazes are based on the SiO2-Na2O-ZnO ternary system where TiO2 is added as nucleation agent. In this study a transparent glaze which is capable of producing willemite (zinc-silicate) was chosen. Depending on time and temperature, the crystal growth rate was primarily designated. Coloring agents like NiO was added into the glaze batch and then both the coloring and crystallization effects of such modifications were studied. Results showed that as well as producing controlled crystallization, color variety was also achieved.