Description
Black oxide or blackening is a conversion coating for ferrous materials, such as stainless steel, and carbon. It is used to add mild corrosion resistance, for appearance and to minimize light reflection. Black oxide is a conversion coating formed by a chemical reaction produced when parts are immersed in the alkaline aqueous salt solution operated at approximately 285 degrees F. The reaction between the iron of the ferrous alloy and the hot oxide bath produces a magnitite (Fe3 O4) on the actual surface of the part.