Cleaning Your Coins

August 30, 2012

A bright, sparkling coin is an item of beauty that will capture the eye and the shine is believed by many to be a pre-requisite of value. Of course this is not so, but misinformed, often novice, coin collectors will seek to bring their coins to a shine anyway. But cleaning coins is a science, and shouldn’t be attempted by those without experience. A badly cleaned numismatic coin can be massively devalued, by as much as 50% in some cases.

If you do have coins that you want to clean, though, there are some basic rules to follow that will help you do so. Of course, asking a child to clean a low value coin is a great way to introduce him to coin collecting. But if your coin has any real value, you shouldn’t attempt to clean it yourself: get the help of an expert.

Types of Coin Cleaning

Coins can be cleaned either mechanically or chemically.

Mechanical cleaning involves polishing, or buffing, and will subject the coin to an abrasive action. The coin will look shiny at the end, but under a microscope or magnifying glass will be seen to have hairline blemishes.

Chemical treatment of coins is usually achieved by dipping in specialist solutions, or sometime vinegar, lemon juice, even coke or tomato sauce! However, an unnatural colour and sheen might be achieved, again easily spotted.

Removing Dirt

Dirt on a coin is itself abrasive, and so has to be removed with caution.  Removal is best achieved by allowing the coin to rest in a warm solution of mild soap for a minimum of ten minutes before picking at the dirt with fingertips of a toothbrush. This should be done gently, and without rubbing. The process should be repeated as necessary before drying by patting with a soft cotton cloth. For really tough dirt, soaking for up to two days in olive oil before beginning the cleaning process often helps.

There are other coatings that affect the aesthetic quality of a coin, and which can be removed by careful cleaning. Some coins were sold to collectors with a PVC coating to protect them. The problem with this coating is that it causes a green film, like a slime, to form on the surface of the coin, and this slime is abrasive. However it can be removed using a cotton cloth dipped in pure acetone and then gently applied to the coin. The green slime will be absorbed by the cloth, and you should continue swabbing until it has completely disappeared.

Acetone can also be used to remove lacquer that has been used to cover the coin and protect it from damage. Unfortunately the practice of lacquering is no longer considered conducive to a coin’s value, and to remove it a coin will need to be immersed in an acetone bath and then rinsed with distilled water.

Tarnishing may be removed from a coin using specialised solutions for coin dipping, but this is the hardest of all cleans to perform. Different solutions are required for different metals, and tarnish removal really is best done by an expert.

Storing your Coins

Just as poor cleaning can damage a coin’s value, so could poor storage technique.

Many collectors will store their coins at home, though from a security point of view it will probably be best to store them in a safety deposit box. Whichever place you decide to store your coins, there are some dos and don’ts that need to be observed. Just as cleaning incorrectly can destroy a coin’s value, so too can poor storage.

The Final Word

Safe cleaning and storage is paramount to maintaining the value of a coin collection. Using the proper storage media should mean that you will avoid the most long-term damaging habits of all: touching and handling. If you should need to handle a coin, then do so only by holding its edge between your fingertips.

Always store your valuable collection securely, and at a temperature and humidity that will cause no ill effects. Don’t be tempted to store your collection under the bed, or in the freezer.

Finally, paying a little to employ the services of a professional coin cleaning service may save you a fortune in lost value when a coin has been cleaned poorly. There is plenty of information available to help you find and select the closest service to you, and asking at your local coin collectors club will be an ideal place to begin your search for the professionals that will help you preserve and enhance the value of your collection.