Ceramic chemistry (or, more specifically, glaze chemistry) studies the relationship between the physical properties of fired ceramic glazes and their chemistry. Although ceramic technicians have long understood many of these relationships, the advent of computer software to automate the conversion from batch to formula and analysis has brought this science within the reach of many more people. Physical properties of glazes in fired products (like thermal expansion, hardness, index of refraction, color and melting temperature or range) are directly (but not solely) related to the chemistry. Properties of glass melts like viscosity and surface tension are also principally products of chemistry.