Cleaning coins, especially old or collectible ones, is a nuanced process that requires careful consideration. While the desire to restore a coin’s luster is understandable, improper cleaning techniques can irreversibly diminish its value and historical significance.
Here’s a breakdown of safe and less safe cleaning methods:
- Evaluate Value: Before attempting any cleaning, determine if your coin holds significant collectible value. If so, it’s generally best to avoid cleaning and consult a professional numismatist for expert conservation.
- Patina: The natural patina (tarnish) on a coin is often appreciated by collectors as a sign of age and authenticity. Cleaning can remove this patina and reduce the coin’s appeal and value.
- Gentle Approach: If you decide to clean, prioritize gentle methods to minimize the risk of scratches or damage.
- Distilled Water Rinse: For removing loose dirt, rinsing the coin gently under a stream of distilled water is the safest option. Avoid using tap water, which can contain minerals or chemicals that might react with the coin’s metal. Pat the coin dry with a soft, lint-free cloth or allow it to air dry.
- Acetone (Pure): For removing surface dirt or adhesives that haven’t chemically bonded with the coin’s surface, soaking in pure acetone (not nail polish remover, which contains additives) can be a safe method. [According to the NGC Coin Collectors Chat Boards] , this is considered “conservation” and not “cleaning” as it doesn’t chemically alter the coin’s surface.
- Household Cleaners: Avoid using abrasive or acidic substances such as baking soda, vinegar, salt, lemon juice, ketchup, toothpaste, or commercial cleaners. These can leave scratches, damage the coin’s surface, remove patina, or cause discoloration.
- Scrubbing/Brushing: Even with a soft brush, scrubbing can cause microscopic scratches that reduce the coin’s value, particularly on collectible coins.
- Harsh Chemicals or Abrasives: Metal polishes, harsh chemicals, or abrasive pads (like Brillo or S.O.S) are extremely damaging and should never be used on coins, says All Valley Coin & Jewelry.
- Silver Coins: Silver coins are prone to tarnishing. A baking soda paste (baking soda mixed with distilled water) applied gently with a soft cloth and thoroughly rinsed with distilled water can be used on low-value silver coins.
- Copper Coins: Copper coins often develop a greenish patina that can be desirable to collectors. If heavy tarnish needs removal, soaking in olive oil for several days or weeks is a milder alternative to acidic cleaners.
- Gold Coins: Gold coins rarely tarnish and are best left untouched. A simple wipe with a soft cloth to remove surface dust is usually sufficient.
If you have valuable or heavily soiled coins, your best bet is to consult with a professional coin conservator or a reputable coin grading service like PCGS or NCS. They possess the expertise and tools to clean coins safely without causing damage or reducing their value.
In summary, when it comes to cleaning coins, remember the golden rule: when in doubt, don’t clean it . If you decide to proceed, always prioritize gentleness and choose methods least likely to cause damage, especially for valuable or collectible coins.
Can I clean coins with Dawn dish soap?
Thanks for asking. Especially bright copper. If you have to use anything to try and get some gunk.
How to clean an encrusted coin?
Soak your coins in warm soapy water ** — Add a squirt of mild dishwashing detergent like Persil Washing Up Liquid to a plastic container filled with warm tap water. Rub each coin inside this soapy bath to work off any dirt or grit. Don’t put all your coins in here at once.