Blackodising Corrosion Resistance is a conversion coating formed by a chemical reaction produced when parts are immersed in the alkaline aqueous salt solution operated at approximately 135º C. 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. It is possible to oxidize non-ferrous metals under suitable conditions to form black oxides. It is possible to apply black oxide at room temperature, however it is not possible to achieve all of the benefits available from the "hot" oxide process. The cold black oxide process routinely shows color variation from part to part and the black material frequently rubs off in your hands.