Fellow Orchidites! I have a technical question to pose you all.
Does anyone know of a good formula for Black Gold? Traditionally
the only alternative was from oxidization. Hydro Tetrachloride
giving the richest, deepest black. But this means has proven to be
So far as I know, and I’ve been looking too, all the folks
selling/producing “black gold” are using a surface coloration, not a
true alloy color. Some are more durable than others. The most
durable I know of (I think) is a silicon nitride coating. It is, I
think, a vapor deposition deposit (though I’m not sure) and for
durability over most metals, is a multi step process requireing
several under coats of different materials to provide a secure
attachment to metal, as a direct coating straight on the gold isn’t
well compatible, and it comes off. Rado watchs use it on some of
their cases and watchbands. It’s an extremely hard material which
resists abrasion, damage, scratching, etc. very well. It can also be
manufactured as a solid material, such as tube sections, which can be
incorporated into jewelry, but as it’s a hard brittle material, not
malleable or ductile, one has to carefully consider how it’s used.
Rado (again) also uses the solid machined material in some of their
products. Machining is only possible with diamond tools, as it is
the equal of carbides (or harder), in hardness, I’m told.
The above, by the way, also applies to blue golds, that have also
been described and sold now and then. They’re surface colors, either
patinas or actual coatings. The sole real exception to this that I
know of is the aluminum/gold alloys which produce a lovely
purple/violet color. This is also a brittle material that can be
shaped only really by grinding, same as a lapidary material, though
it can be soldered, and I’d expect, welded (laser?).
Now, if anyone knows that I’m wrong, and can point me to a true
black gold formula, PLEASE do so. My boss is just itching to find
such a thing too, and I’d get major brownie points were someone to
point me in such a direction with success…