Why you should never clean or polish your coins
Many people think that cleaning old coins brings back shine.
Nevertheless, that is one of the biggest mistakes that collectors can make.
Polishing or cleaning coins corrodes the metal and can completely destroy the collectible value.
In this article, the experts from Schulman b.v. in Amsterdam explains why you should never clean coins, what the consequences are, and how to keep them safe.
Why is it bad to clean coins?
Each coin carries a thin oxidation layer, the so-called patina.
This natural discoloration tells something about the age, the metal used and the conditions in which the coin was preserved.
In silver and gold coins, the patina is actually proof of authenticity.
When you remove this layer, part of the history and the market value disappear.
In international numismatics, “uncleaned” is considered a sign of authenticity. A polished coin loses its grading value immediately.
What happens when you brush a coin?
Polishes, silver cloths or brushes cause microscopic scratches on the surface.
Even a soft cloth can damage the original structure.
The coin may look nicer under normal light, but a professional valuation or auction will immediately recognize marks.
The value often decreases by 50 to 90 percent.
In Amsterdam and other European auction houses, the following applies: polished means degraded.
Why dry cleaning is even worse
Many home, garden and kitchen products contain acids or solvents that affect the metal.
With silver or copper coins, the surface can literally be etched away.
Gold coins often cause color differences or dull spots.
A coin that has been treated with chemicals is used by appraisers in the Netherlands and Belgium as vitiated considered.
How to recognize a cleaned coin
Experienced numismatists recognize this by:
- Unnaturally shiny or smudged surface
- Small scratches around the portrait or weapon
- Discoloration in the deeper parts
- A smooth, dull shine with no depth
Even a delicately polished coin betrays processing.
In case of valuations by Schulman b.v. Amsterdam such traces are always recorded in the report.
How to store coins safely without cleaning them
There is a big difference between scavenge and conserving.
You can protect coins safely without affecting their original condition.
Recommended storage advice:
- Do not touch coins with your bare hands, use cotton gloves
- Store them in acid-free containers, slabs, or capsules
- Avoid humidity and temperature changes
- Only have restoration carried out by a certified numismatist or curator
Schulman b.v. offers professional assessment and advice on the preservation of historical coins in the Netherlands.
What makes original patina so valuable
The charm of a coin does not lie in its brilliance, but in its authenticity.
Dark toning or discoloration is not a shortcoming, but proof of age.
Collectors and auction houses value coins with a original toning just higher.
An untouched coin with a patina can be worth thousands of euros more than a polished version.
Conclusion
Coin polishing destroys historical value and authenticity.
Leave your coins as they are and rely on experts valuation and preservation.
This way, you not only keep their value, but also their story.
