Black Oxide?

Our parts always came glossy, almost "waxy"... then we switched vendors and got the dirty, brown, crappy black oxide that comes off on your hands and clothes. The difference appears to be the "sealer"... or lack of sealer on the brown parts. Caswell sells their regular penetrating sealant and a new acrylic "non-oily" sealant.

Sounds like Electro Coating. Basically a THIN paint process that applies the coating using electrostatic spray or dip. Depending on the material it can be a good finish or a crappy one.

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Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Maybe... But it was 230 lbs. of small parts. Not likely that they went through all that trouble on small parts.

How about Iron Phosphate. It is a harder black conversion coating, which when oiled is VERY shiny and quite durable.

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That sounds like what I know as black oxide. The glossiness is due to a sealant applied after the oxide treatment. There are several variables to control (temp, concentration, time, cleanliness), besides the basic chemistry, so it's not unusual to see variations. One of my customers put in their own line in order to control the process themselves. They use the Penetrate Ultra Liquid on this page, after a very thorough degreasing and cleaning routine. As advertised, the parts come out a very dense black.