What causes crazing on dishes?

Crazing is caused by the glaze of a dish being too small for the clay body. When the dish reaches a high temperature and then begins to cool, the glaze contracts more than the clay body. This creates tension and causes small cracks to form on the surface.

Other common causes of crazing include poor fit between the clay body and the glaze, expansion of the clay body due to absorption of moisture and thermal shock to abrupt temperature changes. For homemade pottery and dishes, crazing can be reduced by firing to a higher temperature or by introducing a longer soak at the end of the firing cycle. Crazing is generally considered undesirable and it lowers the value of certain antiques and fine china.