The passivation process is an immersion method of improving the corrosion resistance of stainless steel parts. This is caused by removing ferrous contaminants like free iron from their surface, restoring them to their original corrosion specifications. Typically, nitric or citric acid is used to accomplish this process. This process is especially useful for 304 commercial grade stainless steel. Commercial grade stainless has small amounts of ferrous iron that remains on the surface and will potentially spot rust if left untreated. Tooling used in the formation of any grade of stainless, including 316 medical grade stainless steel, can leave ferrous iron in the surface. Passivation will stop spot rusting of your stainless steel items. No coating is necessary following this passivation process but it can be used to help long term corrosion on powder coated stainless steel parts.