Pinewood Collectibles

Cleaning Coins

If you want some good advise, “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 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 often. 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 bad 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 more than $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 this advices: Don't clean your coins and ask an expert.
 

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Can You Unclean Your Coins?

The quickest way to ruin a coin is to clean it. Once this is done it is not possible to restore the original surface to a coin that has been cleaned to make it more “shiny.” Harsh cleaning such as is done to “polish” silverware is pretty much beyond remedy. Any attempts to remedy the situation are only going to make matters worse.

Experienced coin collectors generally approve of removing heavy dirt or even filmy surface deposits of contaminants, in order to prevent chemical reactions that can corrode the coin metal. Plain water and maybe some mild soap may be gently applied in this process, but it is very easy to overdo even the use of soap.

Neutral solvents, such as acetone, may be used in removing glue or other foreign deposits. Acetone should be available in pure form at your local hardware store.

Any form of abrasive cleaning removes a layer of the original coin metal. Damage such as this is irreversible. On high-grade coins, the metal flow lines that result from die striking will be weakened, thus undoing the natural luster and leaving a flattened, even if shiny surface.

The best that can be hoped for harshly cleaned silver is that it will retone naturally, from the surrounding environment, over a very long period of time. The problem that arises here is that the more careful you are about using inert storage materials for the coin, the less opportunity there exists for the silver to retone.

Some collectors get impatient and decide to speed up the retoning process. They turn to “artificial toning” by the use of chemicals or heat. This may raise “red flags” with more experienced collectors. Because of the artificial toning, they may be less inclined to buy the coin.

This deliberate artificial toning will not adhere to the abraded surface of a cleaned coin in the same way that it would to the original coin metal. The artificial toning will lack depth and the colors may appear to be “painted” or applied by crayons.
If you have a truly rare and especially valuable coin that has been damaged or harmed by cleaning, why risk further damage by experimenting? Your best bet is to accept the fact that the damage has been done and that its value has been diminished in the process of it being cleaned.

With the exception of freshly dug-up detector finds, cleaning or polishing your coins will do more harm than good. Once metal has been exposed to the air, it is natural for it to oxidize, or tone. If you strip the coin of this toning, not only will you lose any remaining luster, the coin will appear harsh and unappealing, and suffer microscopic abrasions that will lower its grade. Naturally toned coins are worth more than stripped or polished coins.