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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]& sodium thiosulphate [on eBay or Amazon] . 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
BarrysRestoreItAll

Carlsbad, California

2007

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/ 1 lit ammonia [on eBay or Amazon] solution.Bad smelling but very effective-be careful ammonia fumes are very unpleasant, use rubber gloves [on eBay or Amazon] and safety googles [on eBay or Amazon]!Good luck!

Goran Budija
- Cerovski vrh Croatia
2007

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