Here in the U.S. Midwest there is one company that sells black aluminum
cookware. Along with the pots and pans they sell jars of a rub-on refinisher
that is supposed to restore the black color. I think it is a national brand
for the US. You might check to see if there is something comparable in AU.
Second, I think you can do the anodizing yourself but retreiving the
instructions will require a froth search of my office and I am not prepared
for that just now.
Third, check with a local supplier of trophies and plaques. Here in the US
many of the engraved plates that go with these are aluminum and many have
black backgrounds. This may be a local shop process.
Fourth, I have some elaborate and weird instructions for preparing aluminum to
receive coatings. The instructions claim a black finsh that can be used on
the outside of pots without damage. However, the chemicals are just a
dangerous as the arsenic solutions from the earlier post from Greg Schmitz.
Fifth, one source claims that coating the aluminum with olive oil and then
repeated heating and recoatings will generate a durable black coating. This
strikes me as creating a char layer but maybe the olive oil gives a genuine
reaction product. Judging by how hard it is to clean burned residue from some
cookware this might work but I question just how even the coating will be.
Sixth, it is relatively easy and safe to generate a thin copper coating on
aluminum without electroplating. The copper is easier to blacken. Let
me know if you want those instructions.
I've electroplated copper on aluminum and eventually the aluminum oxidizes
under the copper and the copper comes off in big flakes but it took several
years. One warning though, do not try to generalize copper plating to any
other metal. Most methods require cyanide solutions to avoid forming highly
explosive touch sensitive by-products. Even copper is better from cyanide
solutions but for copper there are safer alternatives.
I might even have some other stuff buried in the rat's nest here but this is
what turned up with with just a few stirs of the pot.
E. Robkin
erobkin@uwcmail.uwc.edu
None of these opinions are shared by my employer. For that matter they are
not mine either since it is University policy that only administrators may
have opinions.