Coin Cleaning

One of the pieces of advice frequently offered by well-meaning collectors is, "Never clean your coins." Online they often shout this using all capital letters or at least an exclamation point or three.

But the fact is that many, many coins are cleaned, and improved, modern coins and ancient ones. People -- collectors and dealers -- clean coins every day, using various means, including but not limited to soaking in soap and water, using acetone, and dipping in E-Z-Est Coin Cleaner, and with ancient coins, soaking in olive oil, lemon juice or vinegar, rubbing with a toothbrush or copper brush, and scraping with dental tools. The trick is to know what are considered acceptable surfaces for any given coin type, what methods are appropriate for any given coin type, and how to best use them.

The advice and overreactions are understandable. Many coins in the past have been damaged by overharsh cleaning, particularly by being rubbed with a cloth and abrasive cleaner or scrubbed with steel wool, and their aesthetic appeal and market value have been greatly reduced.

Attitudes among collectors are much different from attitudes among dealers, and attitudes among collectors of U.S. coins are much different from attitudes among collectors of ancient coins. Dealers, some of them, perhaps many of them, routinely clean (conserve, curate) U.S. coins to improve them, and there's a service out there, NCS (Numismatic Conservation Service), that does this. Virtually all ancient coins have been cleaned, since virtually all of them have come into collectors' hands from having been buried in the ground for 2,000 years, give or take, and are deeply encrusted with dirt, organic matter, calcium deposits, horn silver corrosion, bronze disease, and so on.

You have more latitude with ancient when it comes to cleaning than you do with modern coins. Collectors don't typically evaluate an ancient coin's quality, and judge its market value, by examining its surfaces under magnification, though looking at an ancient coin through a magnifier or a microscope can help determine its authenticity. Instead, collectors look at ancient coins in hand with the naked eye, primarily. You hold it and feel it, just as coins were meant to be held, felt, and looked at, ancient as well as modern.

Of course, there are no-no's when it comes to working on ancient coins too. It's considered unethical to fill in pitting or scratches with epoxy or other substances or to re-engrave detail that had been worn away through circulation or corrosion, among other things.

There are collectors who specialize in cleaning ancient coins, and there are are number of online discussion groups that deal solely with this, including UncleanedAncientCoins and Uncleanedcoins. With U.S. coins, collectors can still clean their coins -- it's just more risky. Still, there's nothing preventing anybody from gaining the expertise to do it right. The advice most frequently given by experts is to start with inexpensive coins, and as with cleaning any coins, to start with the most gentle technique and stop before you think you need to. The library of the American Numismatic Association includes books on coin cleaning.

Here are two Athenian Owls I worked on.

The above coin is a classical Athenian Owl tetradrachm, weighing 17.2g and minted in Athens c. 431-413 BC, judging by the style, to finance the Peloponnesian War. It can be attributed as Sear Greek 2526, Kroll 8c, and Szego 15. When I bought it, it had the ugly dull yellow-green toning visible above.

Below is the same coin after a quick soak in vinegar and a brush with a stiff toothbrush. The cleaning revealed detail not previously visible and gorgeous frosty white surfaces, along with a few marks and stains that the toning for the most part had previously covered up. But all told, to my eyes, it improved the coin's appearance, which was no guarantee. Over time, the whiteness the silver will gradually darken until it eventually turns black, perhaps 1,000 years from now, perhaps 2,000 years, though someone else will no doubt clean the coin again before it reaches this point.

The coin above is an emergency-issue classical Athenian Owl fourree, a silver-plated bronze weighing 12.8g and issued c. 405-404 BC. It can be attributed as Sear Greek 2535 and Svoronos pl. 15, no. 13. It was issued by Athens during the tail end of the Peloponnesian War, which Athens was losing to Sparta, when Athens' supply of silver had nearly run out. The style reveals it's an official emergency issue rather than an unofficial plated counterfeit, with the inner corner of Athena's eye beginning to open up, as happened with the emergency-issue gold coinage issued about a year earlier, anticipating the fully opened profile eye of later Owls.

The toning seen on the coin above was so thick and black that it was difficult to determine anything about the coin's surfaces. A quick soak in vinegar and a brushing did little. A very quick soak in Lime-A-Way revealed the remaining silver with its rough appearance and the underlying bronze from where the silver plating had earlier corroded away, as seen on the coin below.

Note: All of the coins illustrated on these pages that are in my possession are stored off site.

Coin Fraud	Counterfeit Coins	Grading Services	Coin Toning	Coin Cleaning	Coin Prices
Censorship	Compulsion	Coin Holders	Coin Photography	Pocket Pieces	Coin Jewelry
Ancient Coins	Ancients Market	Ancients Grading	Attributing Ancients	Language and Ancients	Looting and Coins



	The above coin is a classical Athenian Owl tetradrachm, weighing 17.2g and minted in Athens c. 431-413 BC, judging by the style, to finance the Peloponnesian War. It can be attributed as Sear Greek 2526, Kroll 8c, and Szego 15. When I bought it, it had the ugly dull yellow-green toning visible above. Below is the same coin after a quick soak in vinegar and a brush with a stiff toothbrush. The cleaning revealed detail not previously visible and gorgeous frosty white surfaces, along with a few marks and stains that the toning for the most part had previously covered up. But all told, to my eyes, it improved the coin's appearance, which was no guarantee. Over time, the whiteness the silver will gradually darken until it eventually turns black, perhaps 1,000 years from now, perhaps 2,000 years, though someone else will no doubt clean the coin again before it reaches this point.





	The coin above is an emergency-issue classical Athenian Owl fourree, a silver-plated bronze weighing 12.8g and issued c. 405-404 BC. It can be attributed as Sear Greek 2535 and Svoronos pl. 15, no. 13. It was issued by Athens during the tail end of the Peloponnesian War, which Athens was losing to Sparta, when Athens' supply of silver had nearly run out. The style reveals it's an official emergency issue rather than an unofficial plated counterfeit, with the inner corner of Athena's eye beginning to open up, as happened with the emergency-issue gold coinage issued about a year earlier, anticipating the fully opened profile eye of later Owls. The toning seen on the coin above was so thick and black that it was difficult to determine anything about the coin's surfaces. A quick soak in vinegar and a brushing did little. A very quick soak in Lime-A-Way revealed the remaining silver with its rough appearance and the underlying bronze from where the silver plating had earlier corroded away, as seen on the coin below.

Tale of Two Cleanings