Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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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
⇦this on
eBay or
Amazon [affil links] & sodium thiosulphate
⇦this on
eBay
or
Amazon [affil links]
. 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?
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 - Forest, Virginia 2007 If you like to do it yourself try 200 gm copper carbonate ⇦this on eBay or Amazon [affil links] / 1 lit ammonia ⇦this on eBay or Amazon [affil links] solution.Bad smelling but very effective-be careful ammonia fumes are very unpleasant, use rubber gloves ⇦this on eBay or Amazon [affil links] and safety googles ⇦this on eBay or Amazon [affil links] !Good luck! Goran Budija- Cerovski vrh Croatia 2007 |
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