Re: Cast iron in zinc
Ken:
If your dimensions are close, I come up w/236 sq-in. Adding in for nooks & crannies, and center cavity, might bring it closer to 280-300. You'll need 15-20 amps at least.
Do your anodes add up to 250-300 sq-in? They may be too small even though you've got 4 of them. And 1/2" separation is WAY too small.
Don't know for sure what your yellow shavings would be. After a number of plating runs, I'll build up a yellow sediment in the tank, which doesn't seem to affect plating, but I filter it occasionally anyway, just to be able to see the parts better.
A couple of options:
1) Don't try to plate the whole thing at once. You can plate one half, rinse it, flip it over and plate the other half. It shows a parting line where the 2 halves plated, but most of that will disappear if you acid bright dip afterwards. Don't touch the raw zinc on the first half with your fingers! It will etch your fingerprints into the zinc. Wear rubber gloves if you have to handle to part while flipping it.
2) Put all your anodes on one side of the tank, and your part as far away on the other side as possible. This gets you maximum separation. You will have to rotate the part manually, so that each side gets even coverage. I've done this with larger parts.
3 gallons will certainly be easier to work with, and a rectangular tank helps a lot too.
I don't see any need to blast the anodes. All I do is rinse them off when I'm done, and hang to dry. They do turn dark where they've been immersed in the electrolyte, but it has never affected the plating action. I used a scotchbrite pad to clean them once, but it didn't make any difference.
Sean
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