An article in this weeks Coin World, a coin I collected 35 years ago in New Caledonia, and my new custom set, The Use of Seated Imagery in Numismatics gave me an idea for a little experiment.
I normally do not advocate the cleaning of coins, but in the case of PVC residue there is little you can do for a coin to return it to its natural finish without first removing the residue. This week in Coin World, I read of a man who had cherry-picked an 1841-O, Small O, Closed Bud, Seated Liberty Dime on E-Bay for $99. Estimates however, place the value of the dime at between $10,000 and $15,000. There was only one problem the coin was encrusted in some type of ugly residue.
The new owner of the dime deciding to remove the residue himself by first dipped it in acetone and then rinsing it with water before patting it dry. Still not pleased with the coins appearance he dipped it in olive oil and the residue fell off the coin like a sheet. He then submitted the coin to PCGS with a final grade of XF-40.
The hunt for coins to populate my new custom set led me to an internet post concerning seated coins. There I saw a coin that reminded me of one I collected while serving in the Navy. Everywhere we put into port, I collected at least one of every circulating coin of that country. Then, I placed all the coins I collected into a binder with PVC plastic inserts. Acting in ignorance, I was unaware of the harmful environment I was placing my coins.
In response to the aforementioned post, I retrieved a 1977, New Caledonia, 2 Franc aluminum coin from my binder to photograph and insert into the thread. After years in a PVC insert, the coin had a brownish tacky haze over the entire surface of the coin. I photographed the coin anyway and posted the pictures. Coincidently, the same day I posted my coin I read the aforementioned Coin World article and had a great idea for an experiment.
The first part of my experiment was to take my inexpensive coin and bath it in olive oil. I dont have acetone, but that didnt matter since I thought that acetone would be a little harsh on a coin struck with a metal as soft as aluminum. Immersed in olive oil I gently rubbed the surface of the coin while watching the oil get darker with sediment from the coin. Then I rinsed the coin with water and patted it dry.
The next step in my experiment was to do a stare and compare. For this, I replicated the lighting, camera position, and camera settings exactly as before. The only edits I made were in a raw picture editor where I adjusted the white balance and increased the exposure and the clarity of the photo. For each photo, the edits were the same. Afterwards, I placed all the photos together into a collage for a comparison.
Amazed at the results the coin now has more of its original luster and color. Additionally, it is much brighter and attractive. Before the bath, the coin looked dull and listless. Gone is the tackiness feel of the coins surface. Overall, I consider my little experiment a smashing success.
In summary, I am not sure I would have attempted to clean a coin as valuable as the dime in Coin World instead I probably would have sent it to NCS. However, for coins I do not intend to certify I think the olive oil bath is the way to go. Today, for better or worse I am a little less scared of cleaning my coins.
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