Profile: Metal Finishings Ltd. specializes in a range of treatments such as anodizing (sulphuric, chromic and hard anodising), conversion coatings, zinc plating and passivation on stainless steel. We supply to the aerospace, military and commercial sectors. We offer both nitric acid passivation and nitric/dichromate passivation. Both of these are industry standard. Stainless steel passivation works by removing any free iron (exposed iron on the surface of the part). This leaves a thin, passive layer usually comprised of chromium and nickel that was already present in the material. Since nickel and chromium are so corrosion resistant, this layer provides greater protection to the already resistant base metal.