Re: flash copper
fullthrottle24,
From my experience, nickel will plate directly to a zincated piece of aluminum without the need for a copper strike coat. Copper could be used for filling in slight imperfections in the base metal, but a mirror polished piece of aluminum properly cleaned should take nickel and chrome beautifully. Caswell's suggests that you Zincate first, then Nickel, Acid Copper, Nickel again and Finally Chrome for a true triple chrome plate finish.
It sounds as if the black deposits you were experiencing may have been surface contamination on the aluminum. I restore a lot of antique silver plated pieces and some of the base metals I deal with (Pewter, Britannia Metal, White Metal, Pot Metal, Aluminum, etc.) will streak and flake from time to time in the Flash Copper. Sometimes it is impossible to get the surface clinically free of corrosion the very first time. It takes a lot of media blasting, polishing and de-greasing to make it all stick.
Best of luck,
Curtis
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