Fingerprints And Conservation

There is a correct way to handle your coins for a reason. Our hands contain body oils, which can be acidic. There are also a variety of other elements that we have come in contact with, that when transferred to the coin by improper handling can cause permanent damage to a coin's surface. It is amazing how many coins we see at the NCS with fingerprints. They not only make the coin unsightly, but also may permanently etch its surface if left untreated. The best way to deal with fingerprints is to avoid putting them on your coins but accidents do occur.

If caught when they are fresh, fingerprints can be removed from a coin's surface. When removing fingerprints from a coin, use the mildest treatment possible. This will keep the coin in its most natural state of preservation and reduce the chances of damaging the coin's original surfaces or natural color. There is a big difference between submerging a coin in a solution and rubbing its surface with an abrasive chemical. There is a possibility to leave hairlines on its surface if some dislodged grit is pushed around with the chemicals.

As a fingerprint's residues mature, they will "set" on the coin. In these cases, a mild acidic dip may be needed to remove it. If caught in time, and done by professionally, there will be no trace of the print remaining and the coin can be returned to its original appearance. It is also extremely important to properly neutralize the coin to lessen the chances of problems developing in the future. In spite of what you may have read before, a few submersions in a very mild acidic solution may have no visible effect on a coin's originality if they are performed properly and neutralized immediately. However, do not attempt this on copper coins.

If fingerprint residues are allowed to remain on a coin, they may actually etch the surface. Once this has occurred, it is virtually impossible to remove it without abrasive cleaning or stronger acids, which will almost certainly damage the coin. The etched surface cannot be restored and will be dull and lifeless. In these cases, the cleaning can be easily detected.
When in doubt about the removal of any contaminant for foreign material from a coin, consult a professional. The damage that can result from improper cleaning is almost always irreversible.