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Black oxide on brass problem





2007

I'm trying to put a very dark black oxide finish on a 4" dia. brass disc. as part of an antique radio restoration project.

I tried a copper sulphate on eBay or Amazon [affil link] & sodium thiosulphate on eBay or Amazon [affil link] . It's not dark enough, nor is it very fast. The process leaves behind a yellow "smut".

1)Should I heat the bath?
2)Should the bath be agitated?
3)Is the "smut" typical?
4)How long should the item be in the bath?
5)Any better approaches or should I send the item out to a professional shop?

Brian Justin
hobbyist - Forest, Virginia



Heating the object stimulates the molecular action thus speeding the patina process. We sell a patina which will work simply and quickly to achieve this look, Regards

Barry Feinman
Barry Feinman - Chief Restoration Officer
BarrysRestoreItAll
supporting advertiser
Carlsbad, California
barrysrestoreitall
2007



simultaneous replies

My goal is not to add patina to make the knob look old, but rather to repeat the same process that would have been used in industry back in 1921 to create the very dark black oxide finish on the brass item when it was brand new. I have already stripped what was left of the original oxide with acid and
am down to the original raw brass.

Does your patina solution form a very black oxide layer?

Thanks!
-Brian

Brian Justin
- Forest, Virginia
2007


If you like to do it yourself try 200 gm copper carbonate on eBay or Amazon [affil link] / 1 lit ammonia on eBay or Amazon [affil link] solution.Bad smelling but very effective-be careful ammonia fumes are very unpleasant, use rubber gloves on eBay or Amazon [affil link] and safety googles on eBay or Amazon [affil link] !Good luck!

Goran Budija
- Cerovski vrh Croatia
2007


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