Molochite is a pure white made-made granular material. The granules are hard and refractory. It is made by firing raw low-iron kaolin to very high temperatures (about 1500℃) to bring about maximum conversion of the clay crystal to crystalline mullite (usually 95%+). The latter has high mechanical stability and resistance to thermal shock. Any free SiO2 present become amorphous silica glass rather than crystalline quartz. The result is a material of very low thermal expansion. Molochite is available in a wide range of sizes (from 8 to 325 mesh) and in dedusted form. It is a very uniform. It can be used as a very white firing porcelain grog and aggregate material (but be careful with the material you choose to be sure it has no iron particles). However, its chief use is in the investment casting industry, where successive coats of increasingly coarser molochite slurry are applied onto wax models. After drying, the wax is melted out and the molten metal poured in.