Passivation is a chemical process that is used to help restore contaminated stainless steel to original corrosion specifications. Parts are placed in baskets and submersed into a diluted nitric acid or citric acid solution for a specified length of time and temperature. This process is designed to remove free iron or other foreign matter from the surface of the metal. Passivation, however, is not effective for removing heat tint or oxide scale as a result of heat treating or welding. Other than giving the part a clean finish, the process does not brighten or change the part appearance.