Ray N. writes: I have some silver coins that have been water damaged in a flooded basement. Is there a safe cleaning method that will restore the luster of the coins or am I out of luck?
Luster is the term that numismatists use to describe the effect that light has on a coin when it is tilted or turned in light. It is created by the many radial lines that flow outward from the coin when the planchette is struck simultaneously by the obverse and reverse dies. Chemical cleaners remove metal as well as oxidation from coins and therefore remove some of the flow lines. Once the oxide is removed from the coin’s surface the coin will oxidize even more quickly requiring repeated cleanings. A few “dips” in a product like Jewel Luster over a period of months are enough to turn an uncirculated coin into an AU or lower grade coin.
If the coins are of considerable value, you might explore using the professional conservation services offered by NGC or enlisting other expert assistance. In any case, I would strongly advise against cleaning them on your own.