What is Vitreous Enamel?

Enamel is highly pigmented glass, usually in powder form.   Enamel (or vitreous enamel or porcelain enamel in U.S. English) is the colorful result of fusing powdered glass to a substrate by firing, usually around 1550 deg. F.   The powder melts and flows and hardens to a smooth, durable vitreous coating on metal,  glass or ceramic.