Removing surface lead from brass.

This is completely from John Palmer off the Realbeer website
(http://realbeer.com/jjpalmer/Welding.txt)

<start>"Brass is an alloy of Copper and Zinc with some lead thrown in for
machinability. The lead percentage varies, but for the common brass alloys
used in plumbing fittings it is 7% or less.  Lead is entirely soluble in
copper, but the presence of zinc changes this. In Brass, the lead exists as
minute globules. These globules act as an intrinsic lubricant during
machining. The result is a micro-thin film of lead being smeared over the
machined surface. It is this lead (a very small amount) that can be
dissolved off by the wort. While this small amount of lead should probably
not be a cause of concern, most people would be happier if it wasn't there
at all.

Well, never let it be said that the Space Program never yields technology
applicable to the home. Some chemists working on the International Space
Station Alpha program were consulted for an etchant that could safely remove
the lead from the surface of brass parts. The chemists determined that a
1-to-1 volume ratio of Glacial Acetic Acid (98% by vol.) to Hydrogen
Peroxide (30% by vol.) would accomplish this without pitting the brass. This
procedure was performed in the lab using the standard laboratory
concentrations of these chemicals. The process consisted of a 30 second
dunk, swirl and rinse at room temperature, and was successful in removing
the lead, as determined by a Lead Home Test Kit (swabs). In addition, the
procedure had the added benefit of turning the brass into Pure Gold. (Okay,
the color of, anyway.)

Because 98% Acetic Acid and 30% Hydrogen Peroxide are not available to the
average brewer, the experiment was repeated using the concentrations
available in the supermarket. These are 5% Acetic Acid (White Distilled
Vinegar) and 3% Hydrogen Peroxide. Due to the difference in concentration,
the relative concentration ratio is changed. For the household variety
concentrations, a 2-to-1 volume ratio of Acetic Acid to H2O2 is needed.

The process was expected to take longer with the more dilute solution, so
the brass part was immersed for 10 minutes. The results showed the same gold
color and the Lead Test swab indicated the lead had been removed. The
buttery yellow gold color can be used as an indicator that the process has
completed.  Home Lead Test kits should be available at most hardware stores.

This procedure for removing surface lead from brass can easily be conducted
at home. A 10-15 minute dunk, swirl, and rinse in a 2/1 volume ratio of 5%
Acetic Acid and 3% Hydrogen Peroxide has been shown to be effective. By the
way, the solution can be irritating to the skin so either wear gloves or use
tongs."<end>
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John Palmer also addresses this in his "How to Brew" on-line book
(www.howtobrew.com) in Appendix B under cleaning copper.