Re: flash copper
I find the zincate doesn't penetrate a polished Alluminum. Even after 30 seconds in the Zincate (and that's a lot) you can still see a sheen through the zinc. You can plate over it with Flash copper but it will peel off easily.
A sanded Aluminum reacts a lot quicker in the Zincate say 5 to 10 seconds. The danger here is too much Zinc deposit (darker appearance). Plate over this and it will blister.
So what I do is I Zincate till it starts to change color noting the number of seconds. Rinse it off and examin it. If too dark to my liking, I stick it in pickle #3 for15 seconds, rinse and start over, this time reducing the number of seconds.(or vica versa if it looks too shiny). Do this as many times as you wish until the zincated Aluminum is exactly the right color.
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