The Facts on Black Oxide
Black iron oxide is actually magnetite (Fe3O4).
The process provides a chemical conversion of an existing metal, mostly steel, to form an integral protective surface where nothing is deposited... as contrasted to applying a coating which bonds to metal but does not react chemically. Black oxidizing finishes parts and components with an overall uniformity, even the most complex shapes and configurations. Black oxide does not effect part dimension, hardness, temper or surface properties...
a polished surface retains its gloss, a dull surface retains its matte finish.
The black oxide finish will not chip, craze, peel, drip, crack or rub-off. A black oxide finish has excellent ability to resist abrasion, erosion and rust. Black oxidizing is a safe and non hazardous process for the operator and the environment. For the operator, normal precautions will suffice... adequate ventilation and protective clothing. If bodily contact is made with the solution, washing down with large volumes of water is usually sufficient.
Black oxide solutions contain alkaline materials and oxidizing agents. Prior to disposal, they are diluted and treated to bring the solution to a neutral pH. Sludge formed in waste treatment is normally iron oxide and sodium sulfate, which are not considered as hazardous waste. The advantages and benefits of black oxide finishing are many compared to painting, phosphating or plating: abrasion, corrosion and rust protection; dimensional stability; retention of waxes and oils for better lubricity and reduced friction of moving parts; improves appearance while reducing light glare; extends shelf life of stored parts; improves adhesion qualities for painting; suitable for electronic components as there is minimal reduction in conductivity; and it is certified for automotive and military specs.