Ceramics are produced when metals combine with non-metals. The ionic bonding holds the structure together and the covalent bonding provides chemical resistance. This combination produces materials which have great chemical stability, have high melting points, great rigidity and hardness. Unlike metals which have characteristic melting points, at which they change from liquids into crystalline solids, glasses merely soften as they are heated. This is because they are supercooled liquids and not true solids.
Domestic porcelain contains much more kaolin than dental porcelain, which contains more feldspar.
This makes the domestic porcelain opaque and the dental porcelain translucent. The constituents of domestic porcelain are mixed together, moulded and then fired, during which time a pyrochemical reaction occurs. They are then coloured and glazed. The constituents of dental porcelain are mixed together, fired and poured into water to produce a frit . The porcelain thus produced is then ground, sieved and packed.