Black Oxide


Black oxide, also known as gun bluing, is a conversion coating formed by a chemical reaction produced when parts are immersed in the alkaline aqueous salt solution operated at approximately 285-295 degrees F. The reaction between the iron of the ferrous alloy and the hot oxide bath produces a magnetite (Fe3 O4) on the actual surface of the part. It is possible to apply black oxide at ambient temperatures. You may not be able to achieve all of the benefits available from the traditional high temperature oxide process. The cold black oxide process can show color variations and the black material can frequently rub off. The cold process does not meet military or automotive specifications.


Benefits of black oxide coatings:

  • Does not create any dimensional changes
  • It does not chip or flake
  • Offers improved lubricity
  • Able to withstand high temperatures without discoloring
  • Can be welded
  • Offers cosmetic benefits (gloss or matte)
  • Inexpensive to apply

Black Oxide