Black oxide is a conversion coating formed by a chemical reaction. The reaction between steel and hot oxide bath results in a magnitite coating being formed on the part. The part surface is normally a dark to matte black color after the process. The finish would not be considered decorative but adds an antique or flat black type look. The finish will not flake and is durable. The process also provides improved lubrication to the part to resist galling. It does not exhibit "white rust" so it is excellent for elecrical cabinet brackets.