Porcelain enamel is a glass-based coating that is fused at very high temperatures to steel. Porcelainized steel resists high temperatures, corrosion and abrasion, and it enhances the appearance of steel appliances because it comes in a wide range of colors and lusters. Porcelainized steel is used for range tops, oven cavities, laundry appliances, bathtubs, hot water heaters, cookware, food processing equipment, pipe linings and water-lubricated bearings. Porcelain enamels have the highest lubricity of any coating, because of low friction, according to Porcelain Industries. To produce porcelainized steel, a molten glassy mixture of minerals is cooled and then milled into a glassy powder, called frit, for coating steel.
Fuse a specified mixture of minerals in a smelting furnace to produce frit. The mineral mixture should contain silica and various metal oxides. Weigh them out carefully before smelting, because the composition varies depending on the intended application. Furnaces operate between 1,700 to 2,000 degrees F to make frit for porcelainized steel.
Pass the red-hot molten material between water-cooled rollers to generate thin sheets or ribbons of material. Quench the material with a water spray to shatter the sheet into glassy particles, called frit.
Grind the frit into smaller particles using a mill. Grind the frit into the specified size called for by the intended application or product.
Apply frit to steel, either as a water-based slurry (wet method) or as a dry electostatically applied powder (dry method). Fire the coated steel in a furnace with temperatures in the range of 11,000 to 16,000 degrees F. This process coats the steel with the "ground" coat and forms an inseparable chemical bond between the porcelain layer and the steel surface.
Apply a second and final coat to the steel to give it the desired color and appearance. Fire the coated steel again. Although many steel products require two coats, a ground and a cover coat, some products only need one coat.
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