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Old April 19th 08, 02:51 AM posted to
Peter W.. Rowe,
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Posts: 355
Default hydrogen peroxide/pickle trick question

On Fri, 18 Apr 2008 18:45:26 -0700, in Carl 1 Lucky Texan

I was just wondering if the hydrogen peroxide in the pickle maneuver for
'un-plating' silver (which has inadvertently been plated from touching
iron while in the pickle) would have any positive effect/remove 'firestain'.

1 Lucky Texan

That mix IS a more aggressive pickle, no doubt, capable of dissolving copper
itself, not just copper oxides as normal pickle does. But firestain isn't a
surface oxide. It penetrates into the silver surface. So pickle, and the
peroxide/pickle mix removes surface oxides, and apparent fire stain on the
pickled surface, it doesn't penetrate and remove the oxides that have developed
below the surface. At least not in my experience with the mix. You pretty much
need something that will remove the fire stain layer itself, which means etching
not just the copper oxide in the surface, but to get at it, the silver it's
imbedded in. Thus the various versions of bright dips, which are usually acid
mixes based on nitric acid or it's salts, rather than sulphuric acid (pickle),
since the nitric acid based mixes can dissolve both the copper and it's oxides,
AND the silver holding them too, letting you get the whole surface to below the
affected layer. Buffing of course does the same thing.