Here’s a general rule: You should not clean coins. Decades ago collectors routinely cleaned their coins. This became a no-no when holdering companies began returning those in body bags. Now you get a details grade. However, there are times, coins and occasions when cleaning is called for. We’ll cover those here.
We begin with PVC poisoning. This condition may call for cleaning. PVC stands for polyvinyl chloride, an additive to plastic that makes it pliable. For many years collectors used flexible flips containing PVC. Over time, these chemicals escaped the plastic and coated the coin, leaving a green film on silver, for instance. Now hobbyists use Mylar flips, free of PVC, oils and chemical additives.
PVC flips poison coins with a green tint that eventually eats away and destroys metal.
Here is an example of a coin with that flaw:
You can remove PVC with acetone or MS70 coin cleaner. I won’t use it on the above coin because it is common and worn. Neither would I use it on this coin below. The PVC poisoning is too advanced, eating into the metal.
However, if you have coins with this green slime you might try to clean them.
If so, use a Q-tip. Dip it in MS70 and gently roll the cotton end until the contaminant is removed. Do not forget to dab the rims, too. Then rinse the coin in distilled water and place it on a cloth until air dried. Do not use the cloth to wipe the coin. Also use gloves.
A word of caution: MS70 can strip coins of rainbow toning. Also, I discourage using MS70 or acetone to clean copper coins. It damages eye appeal. Red copper coins especially lose their luster.
If your coin has a light film from improper storage, as this coin did from dust, you can remove that to show luster underneath. Of course, you have to distinguish between dust and other stubborn contaminants. If you have doubts, don’t clean.
Sometimes coins have grit (verdigris) or staining that can be removed with acetone or MS70. The coin below deserved a chance. It was a desirable 1884-O Morgan, but the reverse was stained. I used a Q-tip with MS 70 coin cleaner. As soon as I started, though, I saw the cleaning would fail … and stopped. The grit was removed from a test patch but left evidence of a previous cleaning.
Although some numismatists use acetone to remove ink stains, I never had luck doing that. Stained coins are not straight graded by major holdering companies.
However, a coin like the one above might be a candidate for conservation service. Here’s a video about that from PCGS:
If you want to clean your coins, keep in mind that MS70 is a detergent so it doesn’t remove any metal. However, Jewel Luster, otherwise known as e-Z-est, strips a layer of metal from the coin.
The coin below has been dipped. A novice might not see the telltale dipping modules focusing instead on the fabricated sheen. But a grader would see it immediately.
I know that coin dealers and expert numismatists use similar cleaners with a special formula that they occasionally apply on desirable coins. Typically they destroyed countless coins before developing that formula. That’s how risky this is.
If you try to clean a coin, you have to take responsibility for the outcome. You might go to your local coin shop or dealer and ask if they clean coins and perhaps to show you their methods. That’s how I learned from Scott Nichols. Click the photo below from a past Coin World article.
Alas, Scott passed away in 2016 and his shop recently closed in Ames, Iowa. So you might not have a local mentor as I did. Best place to find them now is in coin clubs. You can view this handy coin club directory from the American Numismatic Association.
You also might appreciate this video from the Newman Numismatic Portal featuring Alvin L. Stern, a professional numismatic appraiser and coin dealer based in Houston, Texas.
Finally, if you buy or bid on coins, you should know the various types of cleaning. Check out this article from Proxiblog.
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