You should not clean coins because it removes their natural surface (patina), causing micro-scratches and altering the original metal, which significantly reduces their historical value and appeal to serious collectors, often making them look unnaturally shiny or "abraded" even if the damage isn't visible to the naked eye. Collectors prefer a coin's natural toning, which signifies its age and authenticity, and cleaning can drop a coin's grade and market value dramatically, sometimes by 90% or more.
It's generally not a good idea to clean coins, especially collectible or valuable ones. Cleaning can damage the coin's surface, remove its natural toning, and significantly decrease its value. Even light cleaning can leave microscopic scratches that collectors and dealers will notice.
The short answer is none. No cleaning will return coins to a legitimate, natural mint state. Coins are best left uncleaned unless it is something like dirt that can be rubbed off without causing damage to the surfaces.
The other main reason you shouldn't clean old coins is that you can easily damage them. Most coin cleaning products are abrasive, and could damage the coin. Non-abrasive chemicals can still react with the other metals found in some old coins.
The safest way to clean a coin (and only for removing loose debris) is to place it under gently running tepid water. In the eyes of most numismatists, virtually any other method technically renders the coin cleaned and thus lowers its value.
While you may be tempted to polish your coins to make them look shiny and new, proceed with caution. Polishing and/or cleaning coins can reduce their value. Older coins that show deep age coloration are more desirable than coins whose surfaces have been stripped away by improper polishing or cleaning.
The coin is dipped into a dilute acid solution that removes the oxidation from the coin along with a small amount of metal. Overdipped coins result in loss of luster which lowers the coin's grade and appeal. According to author Thomas E. Hudgeons Jr., this is the safest way commonly found coins are cleaned.
As a rough estimate, most coins will lose anywhere from 20-50% of their value when cleaned. A coin may lose nearly all if its value of it's cleaned, depending on how the coin was cleaned and the the aesthetic effect of the cleaning on the coin's appearance. Of course, this only refers to collectable value.
Dish Soap. If you want to give your coins a stronger scrubbing than a quick rinse, there's nothing better than your regular dish soap. Just add a bit of dishwashing liquid to a bowl of warm water, mixing the two together until you have a nice, foamy bubble bath in which to drop your coins.
Cleaning coins is a delicate issue!
Personally, I always recommend soaking the coin in distilled water for 24 hours. This can help remove dirt without scratching the surface.
In short, when people ask if they should clean my coins before selling, the answer is almost always no. Keeping coins in their original condition is the safest option. Collectors and buyers assess more than shine. They look for originality, authenticity, and how the coin has naturally aged.
Cleaning almost always decreases value by removing historical patina and causing invisible damage. Patina and “grunginess” are good. What looks like tarnish or dirt is often a sign of authenticity and provenance, especially with historic rare coins. Even gentle cleaning risks harm.
In fact, over-cleaning or using the wrong technique can diminish what your piece is worth. This is especially true for: Antique and estate jewelry: Removing oxidation or polishing down details can alter craftsmanship and reduce historical character.
Well, cola is acidic. It's actually the acid within the cola that's reacting with the rust on the surface of our coins and causing them to return to their original shiny selves. Our cola contains phosphoric acid which is why cola is acidic.
One of the most noticeable indicators is the presence of hairline scratches on the coin's surface which result from abrasive cleaning methods. Additionally, cleaned coins may lack natural luster, which is the original shine that coins have when minted.
Tarnish doesn't tend to have an impact on the value of these versions since the underlying silver contents remain unaffected. No amount of tarnish, no matter how long it's left to develop, can destroy a coin's physical silver content.
Fill a plastic container with distilled water and stir in the mild hand soap in which you will soak the dirty coins for 10 to 15 minutes. After this, take the coins out, lay them on a clean, soft cloth, and use the old, soft toothbrush to scrub each coin gently.
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.
One of the fastest and easiest ways to ruin a rare a coin is by sticking it in silver dip cleaner or rubbing it with something abrasive, like silver polish. For that reason, most coin collectors will advise you not to clean your collectable coins.
According to the NGC Price Guide, as of January 2026, a Susan B Anthony Coin from 1979 in circulated condition is worth between $1.05 and $1.35. However, on the open market 1979 P Silver Dollars in pristine, uncirculated condition sell for as much as $1450.
Take the 1910-S Lincoln Cent, for instance. At first glance, it's just a tiny copper coin — the humble one-cent piece many of us toss into jars or piggy banks. But among coin collectors, this early Wheat Penny is considered a true gem, commanding prices as high as $250,000 in pristine condition.
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Soak in soapy distilled water but never use lemon juice or vinegar on Bronze coinage. Baking Soda can help clean the coins when they are soaked in soapy water.
Cleaning your coins
If you must clean a coin due to dirt or grime, use only a soft cloth or cotton ball with lukewarm water. Never use harsh chemicals, abrasive materials, or polish, as they can damage the coin's surface and affect its value.