Collecting Coins: Coin Cleaning

Some tips on how to clean coins, maintaining their value by correct cleaning, what materials to use, and how to keep them clean.

It is a surprisingly controversial topic: whether or not to clean your coins. Most serious coin collectors and experts maintain that coins should not be cleaned at all, and most serious collectors prefer coins to have their original appearance. Unless done carefully and correctly, cleaning coins can spoil their appearance, and more importantly, lower their value by up to half. Don't be tempted to clean your coins just to make them look new and shiny. If you decide to clean your coins, the most important thing to remember is never to use anything abrasive. This includes such things as metal polish, acid based cleaners or household cleaning solutions. Even wiping a coin with a soft cloth will cause tiny scratches, visible under a magnifying glass, which will reduce the value of the coin.

Never clean a coin whose surface appears to be "˜tarnished' - this slight change in color is normal and is the result of a chemical reaction in which atoms on the surface of the coin have reacted with sulfur compounds. Collectors generally call this natural ageing process "˜toning' and the reaction can not be reversed. Older coins that are tarnished or show a slight discoloration due to age are more collectable - and worth more - than coins that have been scratched by not being cleaned properly. You may want to experiment with different cleaning methods using coins that are not particularly valuable or unique. Once you have a cleaning method that works, you can apply it to more valuable coins.

Dirt and other substances on the surface of most copper coins can be easily and safely removed. The easiest way is simply to soak the coin in olive oil or soapy water for a few days, and then rinsing it under running water. You can also soak coins in lemon juice, or rubbing alcohol. Depending on how much dirt is on your coin, you may have to leave it to soak for several weeks, even months. Soaking the coin for a long period of time will usually get rid of that "˜film' of green stuff that often appears on old coins. The green stuff is actually a chemical that is slowly dissolving the metal in the coin. Silver coins can also be cleaned fairly effectively with toothpaste - regular toothpaste, not the gel type.

After cleaning your dirty coin, never rub or scrub it dry. Always let the coin dry in the open air, blow dry it or pat it dry gently with a soft clean cloth.

If you are buying a coin, there are some signs that can indicate whether it has been cleaned. A coin cleaned with an abrasive will generally have minute scratches on it, and there may be tiny specks of dirt left in the recesses of the coin. Copper or bronze coins that have been cleaned may have an unnatural color, perhaps looking more like a gold coin. Silver coins that have been cleaned can appear uniform in color, including the surface along the tops of the raised letters and numbers. A silver coin that has not been cleaned should have very slight variations in color across the face of the coin.

With proper handling and storage of your coins, you may never need to have to clean them. Some serious collectors go so far as to use thin cotton gloves when handling valuable coins, otherwise you should always hold the coin by its edges, rather than its flat surfaces. Holding a coin by its flat surfaces will leave fingerprints as well as the natural oils from your skin that are difficult to remove. Even tiny drops of saliva landing on the face of a coin will leave almost invisible spots, which are virtually impossible to remove. When handling your coins, always hold them over a towel or other soft surface in case you drop them.

Storing old and valuable coins the proper way is important, and proper long term storage will help to keep coins clean. Coins should generally be kept in an environment with a moderate and constant temperature and low humidity. You can partially eliminate any moisture in the atmosphere by placing small packets of silica gel near to your coins. There are many pockets, albums, folders and display cases on the market to display coins, although in general for valuable coins the best form of display is hard plastic transparent folders. These offer good protection against scratches and abrasions and don't contain any harmful materials or chemicals.

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