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Gassing from cyanide copper bath

January 19, 2011

We are running a Potassium Cyanide barrel copper strike for heavy plating (.4 mils) on steel. The bath temp is 130 F, PH around 9.7 and we are running between 900 - 950 amps at 10 volts. We are working this 350 gallon bath like this about 14 hours/day 4 days/wk performing bi-weekly analysis and adds (typically 25-30 lbs copper cyanide and 50 - 60 potassium cyanide).

During plating, we are experiencing significant gassing. We have more than adequate ventilation so the fumes are by no means a health issue. Regardless, I would like to figure out how to limit the gassing as, from my understanding, this is a sign of inefficiency in the plating process.

Can anyone provide some insight as to what we can do to be more efficient with this bath? Any input would be greatly appreciated.

Paul Douglas
plating shop employee - Minneapolis, Minnesota, USA

A strike is intentionally a very inefficient bath and should not be used to put on 4 mil. You need a strike tank followed by a copper plate tank which can be cyanide or acid with the correct rinses. You can pay for this tank with chemical savings as the copper will come from the anode and not the solution. (as bad) A spray rinse over the plating tank will significantly reduce your dragout and thus cost. Copper is not cheap any more.

James Watts
- Navarre, Florida
First of two simultaneous responses -- January 20, 2011

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Second of two simultaneous responses -- January 21, 2011

There are significant differences between a cyanide copper strike, and a high efficiency cyanide copper bath, including a higher metal concentration. You should contact your chemical supplier for advice on this, because it is more usual to first use a strike and then go to a high efficiency bath in a separate tank. But they may be able to recommend something in between that will work.

Lyle Kirman

Lyle Kirman
consultant - Cleveland Heights, Ohio

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Is there excess cyanide in the bath!

T.K. Mohan
plating process supplier - Mumbai, India
January 21, 2011