Black oxide is used to provide a protective, corrosion resistant coating over metal. It has a uniform black finish that does not alter the dimensions of the part after processing. The coating does not chip or peel and acts as an absorbent to hold oils or wax. Black oxide coatings are used on sporting goods, spark plugs, furniture brackets, mower blades, and other products where a uniform black surface is desired. The coating is economical and offers a variety of valuable properties to extend the service life and improve the performance characteristics of a component. There is no dimensional change when using this surface coating.