Industrial porcelain enamel (also known as glass lining, glass-lined steel, or glass fused to steel) is the use of porcelain enamel (also known as vitreous enamel) for industrial, rather than artistic, applications. Porcelain enamel, a thin layer of ceramic or glass applied to a substrate of metal, is used to protect surfaces from chemical attack and physical damage, modify the structural characteristics of the substrate, and improve the appearance of the product.