Coin Care
How to Clean Coins (and Why You Should Not)
Cleaning destroys value, and graders can always tell. The honest answer is: do not.
Reviewed July 2026
Here is the honest answer, before anything else: do not clean your coins. Not with vinegar, not with baking soda, not with ketchup, not with a polishing cloth, and above all not with anything abrasive. Cleaning a coin removes original surface, cannot be undone, and is visible to anyone who grades coins for a living. The internet is full of instructions for making an old coin shiny. Following them is the single most expensive mistake a new collector makes.
What the Mint actually says
The United States Mint puts it carefully but leaves no doubt. You may be tempted to polish your coins to make them look shiny and new; proceed with caution, because polishing and 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.
Read that second sentence twice. The toning you are trying to remove is the thing collectors want. A century of quiet oxidation is evidence that a coin has been left alone, and being left alone is the rarest condition an old coin can be in.
Why graders always know
Cleaning is not a secret you can keep. Abrasive cleaning leaves fine parallel hairlines across the fields. Dipping in acid strips luster and, done repeatedly, leaves a coin dull and lifeless. Wire-brushing, known as whizzing, produces a false shine that fools nobody with a loupe.
Grading services handle these coins by refusing to give them a straight grade at all. They authenticate the coin and then label it with a "details" grade, and the market discounts it hard. Cleaning marks generally cap a coin at MS-62 or lower. Overdipping does the same. Whizzing caps it at AU-50 or lower. A coin worth a great deal in original condition can become a coin worth its metal.
The one narrow exception
If a coin has no collector value at all, and it is genuinely filthy, the Mint's guidance is mild soap and water, then pat it dry with a soft towel. Do not brush. Do not rub. Brushing or rubbing scratches a coin's delicate surface.
The problem is that you often cannot tell whether a coin has collector value until an expert has seen it, and by then the cleaning is done. When in doubt, do nothing. Nobody in the history of numismatics has regretted leaving a coin alone.
What to do instead
Deal with the environment rather than the coin. Sharp changes in temperature and moisture bring on tarnish and spots that devalue coins, so keep them cool and dry. Hold a coin by its edges, between thumb and forefinger, over a soft towel or cloth; the natural oils on your skin are corrosive, and cotton gloves are better still. Do not talk directly over coins, because tiny droplets of saliva create spots that are, like fingerprints, very difficult to remove.
And get the coin out of whatever is attacking it. Soft plastic holders containing PVC will eventually coat a coin with a sticky green slime that eats into the surface. That is not dirt, and soap will not fix it. Move the coin to a safe holder and, if the damage has begun, take it to a professional. The full storage rules are in how to store coins.
If you are about to sell
Especially then. A dealer who sees a freshly polished 1909 cent sees a coin that has just lost most of its premium, and will price it that way. Cleaning before a sale is like sanding an antique before an auction. Take it as it is. Our guide to how to sell coins covers the rest.
Sources: United States Mint, Caring for Your Coin Collection; and the Sheldon coin grading scale for how cleaned and whizzed coins are graded.
Frequently asked questions
Should you clean coins?
Almost never. The United States Mint warns that polishing or cleaning coins can reduce their value, and that older coins showing deep age coloration are more desirable than coins whose surfaces have been stripped away by improper cleaning. Graders can detect cleaning, and a cleaned coin is capped at a details grade.
How do you clean a coin without damaging it?
If you must remove dirt, the Mint's guidance is mild soap and water, then pat the coin dry with a soft towel. Never brush or rub, because that scratches the delicate surface. This applies to coins with no collector value; a coin that might be worth something should be left entirely alone.
Why does cleaning reduce a coin's value?
Because it removes original surface. Cleaning leaves hairlines and disturbs the mint luster, and grading services cap coins with cleaning marks at MS-62 or lower, labelling them with a details grade instead of a straight number. The damage is permanent and obvious to an experienced eye.
What is whizzing?
Going over a coin with a metal or wire brush to fake the look of mint luster. It is a form of alteration rather than cleaning, it is detectable, and grading services cap whizzed coins at AU-50 or lower.
More on coin care
The Coin Register is an independent educational resource. It is not affiliated with the United States Mint, the American Numismatic Association, any grading service, any dealer, or any site previously published on this domain. Nothing here is an appraisal, a price quote, or investment advice. Coin values change constantly; check a current price guide and a reputable dealer before you buy or sell.