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  for Metal Finishing since 1989
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Black Chromium and Aluminium?

2000

This is my problem:

I do black chrome on copper with a nickel layer in between. (Chromic Acid in acetic acid ⇦this on eBay or Amazon [affil links] with barium carbonate) To get the best results the iron content of the bath must be between 25-30 g/l. But as I use steel anodes, the iron concentration always gets too high before chromic acid is low, and this wastes a LOT of chemicals.

My question is:

I have read form the archives here at finishing, that it is possible to use aluminium anodes in chrome plating.

Does anybody know if it is possible to use aluminium anodes in a black chrome plating tank?

What do the aluminium degrade into? (does it precipitate in the tank)

And last, is these aluminium ions harmful for a black chrome bath?

Simon Oestergaard
- Copenhagen, Denmark

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Using steel or aluminum anodes for chromium, where did you hear about such ideas? For black chromium just as for decorative or hard chromium you should use lead anodes (93%) with 7 % tin.

Sara Michaeli
Tel-Aviv-Yafo, Israel
2000

Sara is right, You should use Lead anodes. We use them in our Black Chrome plating tank, as well as our bright chrome. Carlos

Carlos Cielak
plating shop - Mexico City, DF, Mexico
2001