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Should You Clean Ancient Coins?

An Ancient Bactria Tetradrachm, facing obverse.

Will This Coin Be Worth More If I Remove 300 Years of Dirt?

You brush your teeth, wash your clothes, and clean your car. How can a coin be any different?

Preserve Your Patina

Coins from the ancient world may have a patina or natural oxidation layer on their surface. This has developed over time and may help preserve the coin’s condition, preventing erosion and deterioration. Attempts to remove this patina could result in damage to the coin, which will hurt both its beauty and historical value.

The Risks that Cleaning an Ancient Coin Pose

If you are not a professionally trained conservator, cleaning ancient coins can be detrimental to their value. Chemicals, residue, water, and physical deterioration can wreak havoc on the surface of a coin. Improper cleaning methods can wash away the details and value that those details impart to the coin.

The chemical reactions between cleaning products and the surface of your ancient coin’s metal can form compounds that damage the coin, altering its surface in undesirable ways. Many cleaning chemicals will advance the deterioration of the coin’s metal. The residue they leave behind can further accelerate the metallic deterioration.

Another one of the risks of cleaning a coin is damage caused by brushes. In conjunction with abrasive materials, tiny bits of metal in the design and device may be washed away. While microscopic bits of metal may sound minuscule, the details washed away are what impart history, beauty, and value to the ancient coin.

What Should I Do with My Ancient Coin?

While it is counter-intuitive to avoid cleaning ancient coins, there are restoration and conservation services that can help. These services involve specialized equipment and training to remove contaminants without impacting the value of your coin.

Numismatic Conservation Services (NCS) offers conservation services and sends them to NGC for ancient coin grading, after which your conserved coin is encapsulated and returned to you.

If you have an ancient coin you want to preserve and are unsure of the best method, consult a conservation specialist or a local coin shop today.

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