Cleaning old coins can be a delicate process and the “best” method depends heavily on the coin’s composition and value. While some general cleaning advice exists, remember that improper cleaning can significantly diminish a coin’s value and desirability, especially for collectibles.
- Determine if it’s collectible: Before cleaning, ascertain the coin’s potential value and if it holds any numismatic significance. If in doubt, consult with a coin expert or appraiser before attempting any cleaning.
- Handle with care: Always hold coins by their edges, ideally using soft cotton gloves, to prevent fingerprints and oil transfer, which can be corrosive over time.
- Gentle cleaning for dirt/debris: For coins with loose dirt or debris, a brief soak in clean, distilled water is often recommended , followed by patting (not rubbing) with a soft towel. Rubbing can cause scratches, [notes the U.S. Mint].
- Copper coins: Vinegar and salt can be used to remove tarnish and restore shine to copper coins. [According to wikiHow] , some options are mixing 1⁄4 cup of white vinegar with 1 teaspoon of salt and soaking for 5 minutes, or using ketchup as a mild acid.
- Coins with heavy grime/encrustation: Soaking in olive oil for an extended period can loosen the gunk without harming the coin.
- PVC damage (green spots on copper): A small amount of acetone on a Q-tip can be used to clean coins affected by PVC damage, but [says Quora contributor “Silverstacker63”] , it’s generally best to avoid any chemicals unless absolutely necessary and with expert guidance.
- Harsh Chemicals: Acids, metal polishes, or cleaners like Brasso, Tarn-X, or Brillo pads can permanently damage coins, removing original surfaces and lowering value.
- Baking soda: Baking soda, often suggested for cleaning coins, can be abrasive and cause scratching.
- Vigorous Scrubbing/Rubbing: Any scrubbing or rubbing, even with a soft cloth, can leave hairline scratches that negatively impact a coin’s grade and value.
- Strong Acids: Extended soaking in strong acids like vinegar can strip away the natural toning or patina, which is desirable to collectors and part of a coin’s historical appeal.
Cleaning removes the coin’s original surface, potentially leaving microscopic scratches or an unnatural appearance. Professional coin graders look for these signs, which can result in a lower grade or a “details” grade (meaning the coin has been cleaned or damaged). Cleaned coins can be discounted by 30-90% depending on the severity of the cleaning.
The best practice for cleaning old coins, particularly those with potential value, is to avoid cleaning them unless absolutely necessary and, if necessary, to seek professional guidance from a numismatist or professional coin grading service.
Is WD-40 good for cleaning coins?
The oil-base makes WD-40 reasonably effective at removing it without a lot of work. There is of course some sacrifice when this stuff is removed but fortunately the metal underneath is in pretty good condition and the coin, in hand, is much more presentable.
Which liquid cleans coins the best?
I can help with that. Acetone is the only thing you can use that will do anything and not mess with the coin.