Passivation refers to a material becoming "passive," that is, being less affected by environmental factors such as air and water and is the neutralization of ferrous (iron) contaminant in the surface of stainless steel components. Passivation is accomplished by immersing the parts in a solution of nitric acid. The nitric acid dissolves the ferrous surface contaminants resulting in a corrosion resistant passivized surface.
Ferrous surface contaminants can be the result of contamination caused from the original alloy formulation of the stainless steel. Other forms of ferrous contamination can be from the tooling used in the fabrication, cutting or forming of stainless steel parts. Passivation also adds no surface thickness to treated parts.