Why Cleaned Coins Can’t Be Uncleaned

Posted on 10/1/2009

When submitters learn that their coins have been denied a numeric grade by NGC due to Improper Cleaning, they will sometimes ask whether NCS can “unclean” the coins. To an inexperienced collector, this may seem like a perfectly legitimate request, but veterans know that cleaning cannot be undone. It can be (and often is) hidden beneath toning, whether that toning developed naturally or is induced specifically to hide the cleaning. The expert graders at NGC will always spot cleaned surfaces on any coin, since such action always leaves telltale signs that alter a coin’s character permanently.

In the case of an unworn coin, its fields typically show luster that ranges from prooflike (on freshly polished dies) to satiny (as the dies begin to lose their initial brilliance) to frosty, which is the norm for most mass-produced coins. This gradual erosion of a die’s surfaces imparts a grainy texture which reflects light in multiple directions. This may be seen by turning an uncleaned coin under a lamp, noting that its luster swirls and remains more or less constant in all directions (the “cartwheel” effect). When a coin is cleaned with either harsh chemicals or abrasives, this frosty texture is smoothed out, and the coin’s surfaces lose the peaks and valleys which are typified in its swirling luster. The result is a more uniform, smooth surface which reflects light in just a single direction, the luster turning quite flat and lifeless when the coin is turned obliquely to the light source.

It takes a lot of comparison between cleaned and uncleaned coins for a beginner to learn this distinction, and some people just never quite get it no matter how many examples are presented for study. Like musical talent, some people have it and some don’t, but those who do will still improve greatly with practice. An accelerated learning process may be achieved by attending the annual Summer Seminar held by the American Numismatic Association at its headquarters in Colorado Springs. This event offers both beginning and advanced classes on coin grading. NGC graders are frequently among the instructors volunteering their time, and there’s simply no better way to learn than from those who already know how to make such distinctions and who have at their disposal hundreds of certified coins to demonstrate the differences between natural and cleaned surfaces. For those unable to commit an entire week, the ANA offers mini seminars in conjunction with major coin shows around the country.

Getting back to those coins that are known to have been cleaned, what are a submitter’s options? Well, the situation has been simplified greatly by NGC’s addition of Details Grading as a default option when coins are not able to be graded numerically. While the labeling of a coin as Improperly Cleaned may come as a disappointment to the submitter, it nevertheless serves as a useful learning tool.

Though NCS no longer grades and encapsulates coins, it still does perform conservation work. It must be remembered that conservation is essentially the removal of contaminants from a coin and the stabilization of its surfaces to forestall further environmental harm. Conservation does not include adding anything to the coin. NCS will not tone a coin which has been dipped, it will not fill a hole in a coin and it will not smooth out scratches. There are individuals who advertise such services, but they are certainly not conservators.

Both Mint State and worn coins each have a characteristic look when they have not been cleaned, though this look may be obscured by toning or various contaminants. When the toning or contaminants are removed through proper conservation, the underlying surface of the coin will remain unchanged. An Improperly Cleaned coin, however, will no longer possess its natural surfaces, regardless of whether it is worn or has Uncirculated Details. There is no means, whether legitimate or fraudulent, of restoring its natural surfaces, though there are many deceptive ways to hide the cleaning. This, again, is not conservation, rather it comes under the heading of “coin doctoring” and is frowned upon by knowledgeable collectors and dealers.

This article originally appeared in the September 2009 NCS eNewsletter. See the NCS eNewsletter Archive.

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