Also see "The Synthetic Enamel FAQ"
Porcelain enamel is a specially formulated, highly durable glass permanently fused to metal under extremely high temperatures. The metal may be steel, cast iron, or aluminum. It may be a protective surface for cooking utensils, kitchen and bathroom fixtures, and appliances such as dishwashers, ranges, refrigerators, washers and dryers. It is acid resistant. Porcelain enamel may be a decorative surface of metal, glass or pottery. Porcelain enamel while very durable is also expensive to apply and so is being replaced by synthetic enamels or plastics in many appliances today, in such places as cabinet sides, tops and doors. Range tops and ovens will remain porcelain enamel because there is no good substitute presently to withstand the high temperatures. Older appliances may have more porcelain enamel surfaces.
Appliances. Wash with detergent and warm water and rinse. Do not use abrasive pads or scouring powders as these will scratch the glassy surface.
Decorated enamelware --wash in sudsy water, dry with a soft cloth.
Bathroom fixtures can be cleaned in a solution of 1 tablespoon detergent to 1 gallon hot water or with a foam bathroom cleaner. Avoid using household cleaners which contain abrasives. Porcelain enamel bathtubs made since 1964 are acid-resistant. Older ones may be dulled by acid contact, or other chemicals spilled in the tub.
Kitchenware wash in sudsy water. If necessary use a plastic scouring pad or wooden scraper to remove burnt-on food. Burnt on food may be loosened by soaking in a solution of 2 teaspoons baking soda and 1 quart water. Avoid abrasive scouring powder or steel wool. For heavy baked-on grease, or spills, occasional use of a fine steel wool pad or scraping with a razor blade is ok; just be very careful not to scratch the enamel. Using abrasives, such as steel wool or abrasive powders tends to permanently scratch the smooth glassy surface, and make it harder to clean thereafter.
Lime deposit in teakettles may be removed by a solution of vinegar and water. Bring to a boil.
Bathroom fixtures should be disinfected weekly with a solution of chlorine bleach and water or a spray-on disinfectant or by using a disinfectant cleaning foam.
Rust stains can be removed by using commercial rust remover or by using a solution of 1 tablespoon oxalic acid crystals (poison), dissolved in 1/2 cup warm water. Apply to stain, allow to stand a few minutes, then rinse well.
Sinks. Do not leave acid foods sitting on the sink surface for a long time. Many porcelain on cast iron sinks made before 1964 were not acid-resistant. But many acid fruits such as lemons and other citrus fruits, cranberries, etc., vinegar, salad dressings and other acid foods could possibly etch even acid-resistant porcelain enamel if left in the sink a long time. Perforated or plastic mats protect sinks from damage.
Repairing Porcelain Enamel. Modern porcelain enamel can be chipped but only with a very hard blow that bends the base metal. Damaged porcelain enamel fixtures and appliances can be repaired, with do-it-yourself-kits, or by professionals who do the best, most lasting repairs. A special type of paint is used, as porcelain enamel itself must be baked on under very hot temperatures, so it will not be as durable as the original porcelain enamel surface. Never attempt such repair on utensils used for preparing or cooking food.