I mostly posted this to the net so that folks could pick up
the number for Small Parts, a great place to pick up all
sorts of, well you guessed it already, small parts.
Hmmm, let's assume for the moment that the
Brass (CuZn) was not treated with another metal.
The color would then arise from the copper.
CuO is black, many Cu+2 ions give very deep
blues, you might even call them blue-black.
Examples are [Cu(OH)4]2- and [Cu(NH3)4]2+.
Perhaps the surface of the brass was oxidised
Silver coating sounds like an awfully expensive
way to make colors easily generated without the
silver, but this is the British car industry.
There is a company that still makes what are called metal coloring liquids.
It is called Birchwood Casey. I don't have a direct phone number for
them. A company called "Small Parts Inc.", located in FL sells their
products. 1-305-557-7955. This is a really nice company for screws,
fittings etc.
There are two of possible interest.
One is called Super Blue, gives "deep blue/black" finish on all ferrous
metals. Although, I would have no idea why your Brass would contain iron.
The other is called Brass Black, they say it turns the brass black. Small
Parts could probably put you in touch with Birchwood Casey.
Mark M. Banaszak Holl
Brown University
401-863-2738
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