Too often I have encountered lead solder during repairs. Either a
customer has attempted a DIY repair themselves, or a jewelry store
has done a really low quality job.
Either way, before I can do the repair I must remove ALL of the
lead. I start by physically grinding, cutting with gravers, whatever
it takes to remove the bulk of the lead. Once all the lead I can cut
or grind away is removed, I place the piece in nitric acid, and then
remove it and scrape away and darkened areas ( the nitric both
exposes the presence of any remaining lead, and removes some). I
will often rinse the piece, wire brush it, and then test it again
with the nitric acid, to see if any lead at all remains.
Once I see no reaction to the nitric acid at all, I can go ahead and
do the repair correctly. Any lead at all, if I apply the torch at
gold soldering temps, will destroy the gold.
I charge extra for any repairs where lead has been used, explaining
to the customer before they leave their jewelry for the repair that
the lead has made the entire process much more costly and difficult.