Cleaning coins: removing dirt and value

 

If you want some good advice, “Don't clean your coins” is just that. Does this mean that coins should never be cleaned? No, but usually cleaning your coins removes not only dirt, but also value.

There are really only a two ways to clean coins, abrasives or solvents. An abrasive will leave tell tale signs that a coin has been polished or cleaned. From harsh abrasives such as Brillo pads to mild ones such as tooth paste or silver polish both change the surface of a coin forever by putting lines in the metals surface. Solvents on the other hand tend to be used more. From the mildness of water to the power of acids solvents don't add lines to a coins surface. But an acid actually removes a microscopic layer of metal from the coin, altering the original luster forever.

Most collectors want to buy coins in their most original state, and each stage of circulation has its own unique characteristics. People often clean coins to try to make them look better than they really are. Most collectors and dealers quickly recognize these cleanings and are not fooled.

If there is something on the surface that is harming the coin (such as PVC, or polyvinyl chloride from plastics) cleaning the coin will actually preserve it. Toning, or tarnish, shows that a coin is original and uncleaned. If the toning is nice looking it actually adds value to a coin. Toning is an oxidation of the metal and if it is going too far into the surface of the coin it may be removed to preserve the coin.

Two negative scenarios stick out in my mind. 

Once I appraised a collection of Carson City Dollars. The coins were polished with a buffing wheel. The owner stated that a jeweler friend of theirs had polished the coins as a favor because they were toning a little. Now worth a mere $9,000 the collection would have been worth over $30,000 had it not been polished. If the collection had been left alone or maybe dipped in a mild acid if the toning was harming the coins these folks would have preserved most of their coin value.

The other example was when a man with a metal detector found a rare $20 gold coin. With a squirt of water and a quick rub with the thumb he was able to read the date. But, with that rub the dirt etched the surface and took his $12,000 prize down to a mere $2,000 find. Leaving the dirt on the coin was not an option, but by 'field cleaning' the coin the abrasiveness of the dirt marred the coins surface forever.

Knowing which coins need cleaning or preserving can be determined by asking an expert. I always tell my clients that less than 1 in 1000 coins that come into our store ever need cleaning. Cleaning them the wrong way could ruin them forever. If you are unsure just take the advice, don't clean your coins and ask an expert.