Most of the chemicals to blacken brass are quite nasty, one of the older methods
is to use copper dissolved in nitric acid, this gives off really nasty brown
fumes as the copper an acid react, the resulting solution is then painted on the
brass ans heated, the brass will first turn green and then black, I think that
it's really a coating of copper oxide, it does stick to the brass but will rub
off with use.
there is a nother method used by kodak about 100 years ago, it uses copper clhoride
I cant remember the exact chemistry for this one but I will post it over the next
couple of days
Mike
Mike Hadley
Technical Manager
Spc plus
Wilbury Way
Hitchin
U.K
+44 1462 633100
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