What is the composition of enamel used in cookware?

The term "enamel" in cookware usually refers to porcelain enamel, which is a type of vitreous enamel. It's not a single material, but rather a composite made of several components:

1. Base Metal: The foundation of porcelain enamel is a base metal. This is typically steel, but can also be cast iron or aluminum. The choice of base metal affects the cookware's weight, heat distribution, and durability.

2. Ground Coat: A layer of finely ground glass powder, called the ground coat, is applied to the base metal. It acts as a bonding agent between the base metal and the top coat, creating a strong and durable bond.

3. Top Coat: The top coat is the decorative and functional layer of porcelain enamel. It's made of a mixture of finely ground glass, pigments, and other additives. The top coat provides the cookware's color, finish, and resistance to heat, scratches, and stains.

4. Frit: The raw materials for the ground coat and top coat are combined and melted into a glass-like substance called frit. The frit is then ground into a fine powder and mixed with water and other additives to create a slurry that can be applied to the base metal.

5. Pigments: The color of the porcelain enamel comes from pigments added to the top coat. These pigments are typically metal oxides, which give the enamel its desired color and opacity.

6. Other Additives: A variety of other additives may be included in the porcelain enamel to improve its properties. For example, silica and feldspar are added to increase the glass's hardness and durability, while boron oxide is added to lower the melting point of the frit.

In summary, porcelain enamel cookware is a composite material composed of a base metal, a ground coat, a top coat, frit, pigments, and other additives. This composition provides a durable, non-reactive, and aesthetically pleasing surface for cooking.