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Beginner's Corner: Don't Clean Your Coins!

Beginner's Corner: Don't Clean Your Coins!
Category: Beginner's Corner
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Posted: 03-04-2015 08:59:00 AM

Discover different techniques used to clean coins and why you shouldn't try cleaning your coins at home. 

Those new to coin collecting may have a predisposed idea that the best coins are shiny coins, and while that can be true in some cases, it's not always. This idea tends to lead to the cleaning of coins, which can actually end up reducing their appearance and, ultimately, their value.

Ask any seasoned coin collector how to clean your coins and their immediate response may be, "Dont!" But that doesn't mean it isn't possible. There are "safe" ways to clean coins when you absolutely must, but even those do not guarantee to make your coin "better." It is almost always a bad thing to clean coins. 

The advice to leave your coins alone rather than cleaning them first appeared in the 1962 edition of Seaby's Standard Catalogue, and over time it has appeared the same way with no changes. Therefore, it is safe to assume that this is sound advice.

When discussing cleaning coins, there are several terms used that refer to the act: "whizzing," "dipping," polishing," and "thumbing." Each of these terms refer to a different practice used in coin cleaning. MCM does not condone any of these methods nor do we recommend trying any of them. We are identifying these methods to help you spot them while buying coins.


Thumbing is a form of coin altering where a small amount of body oil is applied to the surface which dull the luster in an area where there are marks. Body grease eventually turns a brownish tint and attracts other pollutants, This can make the coin start to tone an off-golden color. Thumbing occurs when a person handles a coin incorrectly. Rather than either wearing gloves or handling the coin by it's rim, a person pinches the obverse and reverse with their thumb and pointer finger, hence the term "thumbing."


While dipping can be done at home, it is best left to professionals. Dipping is a common practice where a coin that is toned or tarnished is dipped into a mildly acidic solution which removes the tarnish and restores a bright appearance on the surface of the coin. When done expertly, the coin is after rinsed to remove acid completely. After a coin has been dipped, it should be nearly impossible to tell that it was. It is, however, possible to over dip a coin. This leaves the surface acid-etched and dull in appearance. There is no way to reverse the process of an over dipped coin.


Polishing is a coin cleaning technique that is done by hand. Typically, a person puts some silver polish on a soft cloth, folds the cloth in half and then places the coin in between. Then, they will rub the coin in the cloth using their thumb and index finder to clean both sides at once. When the polishing is finished, the coin will be wiped on a clean part of the cloth to remove the polish. 


Whizzing is a technique in which the surface metal is moved mechanically to create the illusion of luster. Whizzing can be done expertly and the most common method involves the use of a high-speed drill, similar to a drill that a dentist uses, with an attachment on the top similar to a fine-haired brush. This tool is used to enhance the surface and smooth away scratches, marks and hairlines. In some cases, heat may be added to the process to actually melt the defects in the coin, but these treated coins can have an unnatural appearance.

Cleaned vs. Uncleaned Appearance

Telling the difference between a cleaned and uncleaned coin can be nearly impossible just by the photo of a coin. But when seen in-person, there can be some giveaways to determine if a coin has been cleaned. When under light, a coin should have a cartwheel-like shine that moves as your turn the coin; this is caused when the metal is squeezed as the coin is struck. This is a delicate appearance and is instantly degraded or destroyed by most of the aforementioned cleaning methods. 

Some other tell-tale signs that a coin has been cleaned is too much unnatural shine, too many dull or shiny spots, the rims do not appear as "clean" as the rest of the coin, or the coin appears clean except around the devices where a person may have had trouble cleaning. 

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About The Author

Kelsey Kay Howard Kelsey graduated from the University of South Florida in Tampa with a B.A. in mass communications. She is new to the world of numismatics, but as the Marketing Specialist for MCM is dedicated to learning all there is to know.

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