Black Oxide Brass

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I would like to know if anyone out there knows the proper process for black oxide on brass. Some people call it brown oxide but this is not true. I have learned that a process exists that you clean and activate the brass and then proceed to oxide. This does not make sense to me. Brass with all of the alloys that it contains would need a copper plate prior to oxidation to allow proper oxidation. Please advise!

Donal Hochstaetter
plating shop - Kansas City, Kansas, USA ++++

Dear Donald,

There are various methods and sequences for coloring copper and copper alloys. There are also proprietary solutions that you can contact any of the supporting chemical suppliers for. One non-proprietary formulation uses copper sulfate and sodium thiosulfate at 1 and 2 oz./gal respectively. Note that the parts may need to be lacquered to retain finish. Hope that provides some help.

Best of Luck.

Ira Donovan, M.S.F.
Kansas City, Missouri++++

You can use next solution:

200 gm copper carbonate 1 lit ammonia(25%) Cold immersion.Objects must be oxide and grease free!

Bad smelling but very effective.Good luck!

Goran Budija
- Zagreb, Croatia++++

You can use 200 gm copper carbonate/1 lit ammonia solution. Very effective but very bad smelling solution. Work outside, use rubber protective gloves, protect your eyes!

Good luck!

Goran Budija
- Zagreb, Croatia++++

If able take to plating shop and have them deposit a cyanide copper coating of approximately 30 microns. Take it home, a light rub under water with 00 grade [linked by editor to product info at Rockler] then immerse in solution of lime sulphur & unchlorinated water at 80 mls per liter. Agitation is needed to obtain an even finish whether you jiggle the object or use a pump to move the solution around do not touch the object until it has dried. The most consistent process I have found for a good result is to rinse in clean cold water then hang free in an oven to dry. Compressed air or hot water are not good as they affect the surface finish. Very lightly rub dusty dry surface with dry steel wool and lacquer.

Dave Coleman
Electroplater/metal polisher - Gordonvale, Qld, Australia++++

Yes, you are correct that per Mil-F-495 a copper alloyed part Should be copper flashed prior to processing, chem. black. Also as mentioned above a Cupric Carbonate solution will provide a black color directly to the brass-but this is not commonly called "black oxide" as the Mil-495 process is referred to.

Bill Grayson
- San Jose, California