On Thu, 06 Aug 2009 08:51:34 -0400, Joe wrote:

(I tried posting this last night from home, but was probably stymied
by the fact that I have changed my system date to prevent W7 from
crashing. Apologies if this is a repeat.)

On another list I read (about coining), someone asked if it is
possible to remove some lead solder from a gold coin. I thought of
using an acid that would dissolve the tin and lead, but what would
that be? Also, would any such acid leach out the alloying metal from
the gold, and would that change the color of the coin?

The coin is a 2 1/2 dollar US piece, in otherwise good condition, so
abrasive removal would probably not be a good option.

I'm not involved in this, but it seems to be an interesting problem,
and if anyone has a workable solution, I'll be glad to pass it on
(with attribution) to the OP.


A quick bit of looking on the web suggests that

a) quarter-eagles are 90% gold / 10% copper; and

b) tin-lead solder can be removed from copper with a solution of 33gm
acetic acid and 50 gm hydrogen peroxide in 1 litre of water; and

c) acetic acid WITHOUT any nitric acid will not dissolve gold

so what I'd do, if minded to do this on my own, would be to remove as much
solder as possible with heating and wiping/wicking, then make an
appropriate solution and watch it. Remember that common white vinegar is
only 5% actice acid, so you'll have to do a bit of extra maths.