The basic composition of enamel is quartz, feldspar, borax and fluoride, belonging to silicate material, the same with
ceramic glaze, liuli (similar with azure stone) and glass. In ancient China, this matter
attached to the surface of pottery or inserter was habitually in the
calling of ceramic glaze, attached to the surface of tile pieces for
building was in the calling of liuli. But attached to the surface of the metals then be called "enamel".