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Copper contamination in cadmium cyanide bath

Q. I have inherited a cadmium cyanide bath at work which can only plate at low current density without getting a dark grey to black deposit. The carbonates are high at approximately 9.25 oz/gal but my real concern is I had the bath analyzed for copper contamination and it was 2537 ppm Cu. I took a liter sample and treated it with zinc dust [on eBay or Amazon] treatment. A third part of the triad of working with your situation would be to have your chemical vendor sell you a non metallic brightener/grain refiner. If you are not using one, I feel you should. Certain ones on the market meet the definition for not being a brightener, i.e., no co-deposited organics.

Gene Packman
process supplier - Great Neck, New York
August 26, 2008

Q. I am trying to find the maximum copper content for a cyanide cadmium plating bath. I've seen recommended numbers as low as 10 ppm. In addition, if the copper content gets high (i.e., 2000-3000 ppm) and the operators compensate by increasing the current density, what problems might that lead to? For example, are you now plating a cad-copper alloy? Are you going to see stress, adherence, efficiency problems?

Chad Leach
Plating Shop - Dayton, Ohio
April 28, 2010

A. Yes you are co-plating the copper, so all of your properties are impacted. I can't give you a hard limit, but <10 would be good, <50 might be okay, above 80 is too high for sure. 2000 means you need to forget about salvaging your bath. Eliminate the source of your copper contamination and start over with a fresh bath. That's my opinion anyway.

Jon Barrows, MSF, EHSSC
GOAD Company

Independence, Missouri

April 30, 2010

Q. How do we remove copper contamination in a cadmium bath solution? Only by dummying? Thank you

Pierre Legault
shop employee - Montreal, Quebec, Canada
February 12, 2019

A. Hi Pierre. We appended your question to a thread which discusses quite exacting copper contamination levels and what to do about them. If questions remain, please give us good details of your own situation rather than phrasing questions in the abstract -- the thread is moving backwards :-)
Thanks!

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2019

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