chemically de-oxidizing cartridge brass

[MissingLink]

I recently came into a small lot of WWII-era .50BMG brass, but it was heavily oxidized leaving a dark brown patina. I wanted to use these to build a display, so I decided to shine them up a bit. At first, I tried tumbling them in walnut and corn cob, but that didn't do anything. I'm lucky enough to have access to a well-stocked clean line, and decided to give the brass a dip in Oakite 34. Oakite 34 is a mixture of: chromic acid, potassium bichromate, sodium silicofluoride, sodium hydrogen sulfate, sodium bichromate, etc., etc. It's normally used as an aluminum deoxidizer, but the manufacturer also recommends it for brass, copper and bronze.

So, all the brass to be cleaned looked like the piece on the left to begin with. A very dark brown, but smooth surface texture. After a quick 60 second dip in Oakite 34 (followed by 3 rinses in DI water), the brass looked like the cartridge in the middle; a pinkish-yellow, but the brown was gone. I tried tumbling in corn cob with mineral spirits at this point, but it's slow going. It's cleaning up, but taking a while. While the tumbler was running, I gave a couple pieces of brass a good polishing with Never Dull and got the case on the right.

So, it's a little work, but the Oakite 34 did most of the hard work.



-WRM

 

[HAZORD]

Never had access to Oakite, but the list of chemicals seems quite long. Have you tried tumbling it in the stainless steel pins used for small arms casings? They clean very well with some Dawn dishwashing soap, water, and some Lemi Shine.

 

[MissingLink]

HAZORD, I have not, but I certainly would have tried it if I had access to such equipment. I only have vibratory tumblers at home.

-WRM

 

[raymeketa]

Plain white vinegar with a dash of table salt works as well. Also, a dip in CLR will remove the brown patina and any corrosion hiding under it.

There are many, many formulas out there that will work. Probably as many formulas as there are collectors. And, once you have those cases nice and shiney, there are formulas to add back just a tad of the patina, but only enough to make them look their un-touched best. Collectors, as a rule, do not like bright shiney brass.

Ray

 

[MissingLink]

Collectors, as a rule, do not like bright shiney brass.

I can understand that, and would never do this for anything remotely collectible, but .50BMG brass is a dime a dozen.

-WRM