A friend of mine recently found an old silver coin (1697) with a
lump of what looks to be rust embedded on the face of the coin.
He's tried all sorts of things to get the lump off, but with no
success. Anyone have suggestions?
Another cleaning option that might work is the home brew method used
to remove tarnish from silver.
Place a piece of aluminum foil in the bottom of a glass dish.
Put enough warm water in the dish to cover the item(s) being cleaned
by about 1/4" (6 mm).
Add a tablespoon or more (depending on the size of the dish) to the
Lay the item(s) being cleaned in the dish so they contact the
Check periodically for removal of tarnish (rust).
The hi-tech version of this is the Speedbrite Ionic cleaner. One of
these might also work.