Porcelain enamel is the application of glass-like coatings to metals such as steel, cast iron, aluminum or copper. The purpose of the coating is to improve resistance to chemicals, abrasion and water and to improve thermal stability, electrical resistance and appearance.
The coating applied to the workpiece is a water based slurry called a “slip” and is composed of one of many combinations of frit (glassy like material), clays, coloring oxides, water and special additives such as suspending agents.
These vitreous inorganic coatings are applied to the metal by a variety of methods such as spraying, dipping, and flow coating, and are bonded to the base metal at temperatures in excess of 500 °C (over 1000 °F). At these temperatures, finely ground enamel frit particles fuse and flow together to form the permanently bonded, hard porcelain coating.
At the time of the 1982 rulemaking there were approximately 130 porcelain enamel facilities in the United States.
This article comes from epa edit released