aspeed

I used to work in a place where we did chromating.  First we dipped it in a hot tank of  I think.  just strong soap.  Then rinsed in cold water.  then a couple of minutes in etch which I think was nitric acid diluted a lot with water.  It would turn the aluminum black or grey, especially 6061 T6.  Then rinse in cold water.  It would make your fingers go black but you could wipe it mostly off unless it was left in too long (breaktime)  Then rinse and into deoxidizer  for a few more minutes.  This would take ALL the black off very well.  Then rinse and into the chromate tank for a very specific amount of time.  A few seconds for clear chromate and a couple of minutes for a gold chromate.  Then hot water rinse.  A motor would look nice in the gold colour.  I think  it would let the heat out better than some of the anodising coatings I have seen.  You could touch the alum. and your fingers would not turn black after.  Anyway,  the DEOXIDIZER would be the one to get a hold of.  No idea where to get it, or even if it is sold to the general public.  It might work for the black motor though, say after the etch and into the deoxidizer.  Maybe check into a coatings company in your area.  They would likely want money (who doesn't)  I would just leave it, tell everyone it is a special coating and charge them $20 to do theirs.  or study up on what the deoxidizer is made of. and try and get something similar.  I can't find out anymore.  I moved.  It would make you sneeze when you pulled the part out.