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Problems with plating brass?

I work in a plating shop and I've been plating for a year on a hex line. Now I know that brass should be the easiest to plate but I've been having problems with microfines and blistering. I can't figure out what the problem is but I figured out that if I Copper Strike (cyanide copper) brass after activating it in acid salts, it comes out flawless when I pull it out of the Nickel. Yeah my problem is fixed but I want to understand what causes this. Because you shouldn't have to copper strike brass. Anybody have any ideas?

Mike Wilson
Plating shop employee - Greenwood, South Carolina, USA
March 18, 2009

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First of three simultaneous responses --

If the brass contains lead, as free machining brass does, then you'll form insoluble lead salts in HCl or sulfuric acid and this will cause adhesion problems. Cyanide may solve the problem, but substituting 15% fluoboric acid in the precleaning will be a better answer.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
March 20, 2009

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Second of three simultaneous responses --

The lead on the "leaded brass surface" is the problem. Lead forms insoluble salts with HCl and Sulfuric Acids. Predip in 50% Fluoboric Acid, (that is not Hydrofluoric acid !), then copper strike (NOT IN CN as it also forms a lead insoluble), but in a Copper Fluoborate solution,now you have the lead covered up and can do anything else easy, plate anything .

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

March 20, 2009

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Third of three simultaneous responses --

GIVING COPPER STRIKE TO BRASS IS GOOD IT PROTECTS NICKEL SOL.FROM CONTAMINATION OF ZINC.

Ajay Raina
Ludhiana, Punjab, India
March 21, 2009

Thank you all for your input. Really appreciate it.

Mike Wilson
- Greenwood, South Carolina, USA
May 4, 2009