Letter 32076

Lead Leaching for Brass  

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We manufacture high end faucets. Chrome, Gold, Black Nickel etc.... The faucets are actually made of Brass and we electroplate them in various tones and colors. I was asked if we can do what was called "Lead Leaching" Prior to electroplating. I was told that this particular type of brass has a small concentration of lead when it is casted.

I am concidering using a Ferric Chloride solution or maybe even a Sulfuric Biflouride Solution.

What kind of solution should I use?

How can I tell if it is effective?

Well thanks for any help or suggestion.

Richard Perez
faucet mfg. - Torrance, CA, USA

I have no idea what you mean by "lead leaching". Cast and wrought brass destined for machining,frequently contains lead. When machined this lead smears all over the surface. Lead forms insoluble salts with sulfates and chlorides. Leaded brass must be pickeled in 50% Fluoboric Acid which does not form an insuluble salt with lead. Then apply any kinds of electroplating.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

Free machining brass contains a small percentage of lead. When the brass is machined this can result in a thin layer of lead being smeared over the cut surface, often giving it a "light grey hue" appearance. Trying to plate onto this can be disasterous unless it is correctly processed. One of the ebst ways of removing the lead is to soak the brass in a solution of fluoroboric acid (ca. 20%). This will then make the surface free of lead and plateable

Trevor Crichton R&D practical scientist - UK

I ran an automatic plating machine used for bright nickel-chrome plating of plumbing fixtures. I used sulfamic acid after cleaning. Lead sulfamate is soluble and much less dangerous than fluoboric acid. After the acid dip I installed a copper strike. The copper made a world of difference by eliminating what was referred to as "stardust", i.e tiny pits from the lead on the surface and from lead removed in the acid. Also the copper strike protected the bright nickel from constant lead contamination. The parts looked like good jewelry compared to before copper strike.

If you use fluoboric acid to remove the lead from the surface, there will be an increase in pitting. The sulfamic acid dip was a short one not designed to remove all the lead, but only to activate it for copper plating.

Don Baudrand Don Baudrand, Consultant   Poulsbo, WA. USA

Richard

If youre still having the problem, leach in acetic acid for 4 to 6 hours;

Use the acetic acid as supplied . It helps to provide a lead free surface.

Acetic acid rinses away freely. Leaves no lead on the surface.

Regards

Asif Nurie Atlanta Global Limited New Delhi, India

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