Should You Clean Your Old Coins?

Key Takeaways:

1. Never clean your coins. Cleaning almost always decreases value by removing historical patina and causing invisible damage.
2. Patina and “grunginess” are good. What looks like tarnish or dirt is often a sign of authenticity and provenance, especially with historic rare coins.
3. Even gentle cleaning risks harm. Professional graders and dealers can detect cleaned coins and lower their value accordingly.

The short answer is simple: don’t clean your old coins. Even well-intentioned cleaning can permanently reduce their value, strip away historical patina, and leave invisible damage.

This article outlines the key reasons numismatists and collectors avoid cleaned coins, the role patina plays in historical and market value, and the best practices for safeguarding collections—whether they’re personal finds or inherited heirlooms.

The Risks of Cleaning Coins

A coin’s value is derived from its metal content, of course, but also its condition, its age, its rarity, and its historic significance.

Consider the 1885-CC Morgan Silver Dollar. Minted in Carson City, the “CC” Morgan Silver Dollar is highly-prized rare coin among collectors due to its historical significance and limited production.

Coins like this offer far more than just metal content: they embody the legacy of a bygone era in American minting and can tell stories of the Old West, rare production methods, and evolving coinage designs.

Cleaning such a piece would strip away a patina that documents decades of history, diminishing both its value and its historical narrative.

Part of the grunginess that you may find on your coins may be a function of its provenance. The patina of the coin could serve as a sort of documentation of its historical legitimacy and rarity, as coins age differently over time.

In other words, what looks ‘dirty’ may actually be a sign of authenticity and age. Discolorations or other colorations on a coin might not be a sign of dirtiness, but rather an indication of its authenticity.

You also might impart new damage to the coin as part of the cleaning process. New nicks and dents in the metal – even if they aren’t detectable to the naked eye – can dramatically reduce the coins’ value.

Furthermore, professional coin dealers and graders will know if you’ve cleaned or attempted to clean your coins. You may leave residue behind or create pits in the metal – both of which usually mean a decrease in value.

Unless you own coins that a) derive all of their value from their metal content or b) are tarnished to an extreme degree, there is little to gain from giving your coins a wash. The best result you can hope for when you clean your coins is that nothing happens to their value, so at the very least, you’ll be saving yourself the time it takes to clean them.

What to Do Instead of Cleaning

• Leave coins as they are before appraisal: Any attempt to improve their appearance can lower their value. Let a professional determine their worth in original condition.
• Store them properly: Use protective holders such as 2×2 flips, capsules, or acid-free cardboard holders. Avoid PVC plastics, which can chemically damage coins over time and keep coins in a stable, dry, and cool environment.
• Handle with care: Pick up coins only by their edges — never by the faces — and ideally while wearing cotton gloves. This prevents oils and dirt from your fingers transferring onto the surface.
• Protect the patina: That natural toning is part of the coin’s story and proves its authenticity. Preserving it is more valuable than polishing it away.
• Rely on professionals: If coins genuinely require conservation (e.g., severe corrosion), let experts handle it. Trusted organizations like PCGS (Professional Coin Grading Service) and NGC (Numismatic Guaranty Corporation) are industry standards for grading and preservation.

If You Must Clean Your Coins

If you absolutely must clean your coins, take them to a reputable professional. If the pro is hemming and hawing about completing the job, take it as a sign that they are strongly opposed to the idea.

There is no home remedy or washing method to recommend you use. The only people who might clean their own coins properly are those with an incredible amount of experience working with both an extremely gentle touch and with a select few cleaning agents that don’t penetrate the metal. Even if you do know how to do it properly, you may not possess the manual dexterity required for the job.

Handling an Inherited Coin Collection

The best thing to do is to have it professionally appraised and graded immediately after receiving it. Don’t remove anything that comes with it in its packaging – even if it appears superfluous or unseemly.

You may discover the previous owner already cleaned them, which is irreversible. Cleaning will only compound the damage by interfering further.

Unfortunately, a cleaned coin cannot be “uncleaned,” if you will. Whatever patina is lost or damage is incurred is permanent and irreparable.

Whatever condition you receive the coins in is the best condition that they will ever be, so don’t waste time or allow them to pick up more damage or wear. Take them to a trusted appraiser or send them to the Professional Coin Grading Service (PCGS) or National Guaranty Corporation (NGC) – the two industry standard organizations when it comes to coin appraisal.

Learn more: Next steps after inheriting a coin collection

Numismatists vs. Collectors: Perspectives on Cleaning

Both of these groups prefer that coins not be cleaned, although for different reasons.

Numismatists are students of the history and processes required to make a particular coin. Coins are valuable as historical pieces and deserve to be treated as such, much like any piece in a museum would be afforded a high level of care and attention.

Coin collectors are usually more interested in acquiring the most interesting pieces for their collections than in the pure historical reference contained within an individual coin. However, collectors are also more apt to trade their coins, and cleaned coins are decidedly harder to sell than coins left in their present condition.

The Best Approach: Leave Them Be

New collectors have an impulse and desire to clean coin collections. They often want the pieces of the collection to display the underlying brilliance of their constituent metals.

However, coins are different because many of them reflect particular periods in history, including changing production techniques, alternate and rarely-used locations, and importance to various stakeholders during their existence. For instance, a coin produced prior to 1800 in the United States is a genuine piece of American history, and is not only one of the first coins ever produced by the country, but may have been used or circulated through the hands of some of our forefathers.

So, cleaning a coin like this could literally be washing hundreds of years of history off of it. If a coin looks nasty, slip it into a plastic bag and put it somewhere safe until you can have a trained eye take a look at it.