How To Clean Oxidized Coins (If You Dare!)

Joshua McMorrow-Hernandez

Published: October 12, 2023

Many people want to know how to clean oxidized coins, but should you? That’s the question many people ask, especially when it’s well known in numismatic circles that you generally should not clean coins.

For entertainment and informational purposes only, we present some methods below for cleaning oxidized coins.

photo of several silver coins that are discolored due to oxidization

When coins oxidize, the outer layer of metal often changes color.

What Are Oxidized Coins (Toned Coins)?

The thing about oxidation is that it’s hard to stop. Metals oxidize due to their chemical reactions with oxygen, which is pretty much everywhere in Earth’s atmosphere. One of the few ways to prevent a coin from oxidizing is to house it in an inert environment—one that is essentially devoid of air and is airtight.

Barring that, coins exposed to oxygen will eventually develop some kind of oxidation. In many cases, this isn’t a bad thing. Oxidation is just the metal’s natural coating it develops to protect it from further corrosion or other damage.

Oftentimes, this oxidation takes on the form of very beautiful toning. More and more people in the hobby of coin collecting not only appreciate toning on coins but embrace it—seek it out. After all, oxidation—when left to Mother Nature’s devices—is indeed a very natural thing.

Still, there are people who simply don’t like toned coins. They don’t want any signs of oxidation whatsoever on their coins. What do they do then?

Can You Clean Oxidized Coins?

Many collectors wrestle with these questions in part because in the back of their minds they know cleaning coins is generally a fool’s errand. Cleaning virtually always lowers the value of a coin. It can irreparably damage its surfaces when abrasives or strong acids are used.

In some cases, no amount of time or patience will heal a coin that has been abrasively cleaned, because scratches left from an etching or physically harsh cleaning never naturally repair. They’re there forever. Even if the coin retones, those striations will always be there—they don’t heal.

Should You Clean Oxidized Coins? Is It Worth It to Clean Oxidized Coins?

One thing someone should ask themselves when contemplating cleaning an oxidized coin is, “what’s the goal?” What are you trying to achieve by cleaning your coin?

If what you really want is to turn your toned Morgan dollar into a blast-white Morgan dollar, you’re probably just better off selling the coin you have. Then use those newly acquired funds to buy the blast-white coin you want. Because once you try cleaning the oxidation off your toned coin, whether by way of acids or abrasives, you can pretty much count on wiping out 30% to 50% (or maybe even more) of its numismatic premium. No ifs, ands, or buts.

How To Clean Your Oxidized Coins

Neither this author nor Gainesville Coins endorses the idea or practice of cleaning coins, period. As we hope we’ve conveyed here, cleaning coins is generally a pointless pursuit. It will almost always damage the coin and result in more or less halving its numismatic value.

So, before you clean any oxidized coins, think carefully about what you’re attempting to do. Remember, you’re never going to make an old coin look new again—not gonna happen!

We understand that if you’re reading this far into the article, you’re either here for affirmation as to why you should avoid the temptation of cleaning your oxidized coins or still wanting to find out more about some of the methods for doing so.

The list below covers many popular coin cleaning methods. You can also follow the link to learn more about safely cleaning silver coins, specifically.

Ways To Clean Coins With Oxidation

Vinegar – One of the most common methods for cleaning coins is dipping them in vinegar. White distilled vinegar usually provides the most potent results as it has some of the highest acidity levels among any household vinegars. It is the acidity that will help cut through oxidation on a coin.
Lemon juice – Another highly acidic solution is lemon juice, which can help remove oxidation from a coin. As with vinegar, the most drastic results are usually seen with longer immersion of a coin directly in lemon juice.
Ketchup – This is one of the most common household food items and provides high levels of acidity thanks to its tomato content. Unlike lemon juice or vinegar, which are runny liquids, ketchup is usually thicker and can be applied to the coin in a copious layer for many minutes to help combat oxidation.
Toothpaste – We move from the acidic solutions, which clean coins using chemistry, to the abrasive options, which remove oxidation through physically scraping the coin. When rubbed onto a coin’s surface, the abrasives in toothpaste can help remove oxidation and other surface material.
Baking soda – In general, baking soda tends to be even more abrasive than toothpaste. When applied with enough vigorous pressure, it may remove most or even all signs of oxidation, so long as the coin has no corrosive pitting.
Jeweler’s cleaner – Jeweler’s cleaners are often used by people who want to clean oxidized coins, as many of these solutions claim to have non-scratch formulas for removing tarnish. Cleaning a coin with a jeweler’s cleaner can be done by soaking the coin in the solution for a period of several minutes, though it’s best to read the product’s labeled instructions, as each agent has its methods for best use.

close up photograph of a copper coin with green-colored corrosion

The outer layer of discoloration on a coin, known as a patina, will often appear green on a copper coin. This is also called verdigris.

What Not to Do When Cleaning Coins

As stated earlier, you should avoid attempting to clean coins as a general rule. If you really feel compelled to do so, there are some important things that you should not do under any circumstances.

Don't use harsh chemicals – There's a good reason that the methods listed above all used household items like lemon juice or baking soda. Harsher chemicals may have a more dramatic and immediate effect on the appearance of your coins. This can permanently ruin them, as the chemical reactions aren't easily reversed.

Don't use abrasive brushes – Many coin cleaning guides call for "lightly" brushing your coin to remove dirt and grime. Unfortunately, this is very bad advice. It will almost certainly result in scratches and unattractive marks on the coin. Once scratched, there is no way to remove the offending mark. Instead you should use a soft, damp cloth when wiping down a coin.

Don't dip your coin in silver – Sometimes collectors will try to freshen up a coin's appearance by dipping it in a thin layer of silver (or some other metal). The industry term for this is "whizzing." This is a huge mistake. It flattens the design of the coin and removes any original luster, making the dipping process more obvious. Moreover, it's a taboo in coin collecting to add (or remove) any layer of metal from a coin. If a whizzed coin gets graded, the grading service will indicate that the coin has been improperly cleaned.

More Coin Cleaning Tips

Remember, whether you use an acidic cleaner, an abrasive, or a hybrid solution of some kind, any alterations to a coin surface, whether or not it leaves scratches or other signs of impairment, will almost always result in lowering a coin’s value. A trained eye will usually spot the cleaning from a mile away, especially when the cleaning has been done by an amateur.

Your best bet? Leave your coins alone! If you prefer coins that have no signs of oxidation, toning, or other natural chemically induced hues, sell the ones you don’t like and buy the ones you do. This will ensure that no coin has been permanently altered for generations to come due to mishandling, while you can build your collection or portfolio with the pieces you and your aesthetic eye can appreciate.

Joshua McMorrow-Hernandez is a journalist, editor, and blogger who has won multiple awards from the Numismatic Literary Guild. He has also authored numerous books, including works profiling the history of the United States Mint and United States coinage.

Read more about the coin collecting hobby from the numismatic experts at Gainesville Coins:

Proper Coin Care: Cleaning and Storage

Does Cleaning Coins Decrease Their Value?

How To Clean Silver Coins Safely

Why Does Silver Tarnish?

How To Collect Coins For Beginners: Coin Collecting 101

How to Buy Junk Silver Coins: Complete Guide

Numismatics Guide: Discover the Thrill of Coin Collecting

Collector Resources for Understanding the Hobby of Collecting Coins

Posted In: blog