Why you shouldn’t clean your coins

What cleaning does to a coin

Cleaning can’t be undone. Rubbing, polishing or dipping leaves changes on a coin’s surface that experienced graders can see.

NGC, one of the major coin grading services, says there is no means of restoring the natural surfaces of an improperly cleaned coin.

Each method leaves its own mark.

• Rubbing and polishing leave fine scratches called hairlines. A soft cloth is enough to make them.
• Dipping is a chemical bath. It strips the color a coin has taken on with age and takes a thin layer of metal with every dip.

What is lost

A coin that has never been cleaned still has its original surface. On an unworn coin that surface carries mint luster, the shine left by the way the metal flowed when the coin was struck.

Turn such a coin under a lamp and the light swings around it like the spokes of a wheel. Harsh cleaning smooths the surface, and that shine turns flat.

The darkening on old silver and copper is called toning. It forms naturally over time as the metal reacts with its surroundings, and it is not dirt. Toning runs from pale yellow through blue, gray and brown to black, and copper coins turn from red to brown.

The U.S. Mint tells collectors that older coins with deep age coloration are more desirable than coins whose surfaces have been stripped by improper polishing or cleaning.

What grading services do

NGC and PCGS, another major grading service, both grade coins on a scale from 1 to 70. Major grading services typically give a cleaned coin a “details” grade instead of a regular numeric grade.

The label then describes the amount of wear in words, such as “VF Details” for Very Fine, and notes the problem. On an NGC label the note may read “Cleaned”, or “Improperly Cleaned” on holders from before 2018. PCGS prints a problem code, and 92 means harsh or abrasive cleaning.

What to do instead

Handle your coins as little as you can until someone has looked at them.

• Leave dirt, dark color and spots alone.
• If you need to move a coin, hold it by the edges over a soft towel. Fingerprints on the faces can leave permanent marks, especially on proof and uncirculated coins.
• Leave coins in their albums, flips, holders and Mint packaging, and don’t open rolls.
• Taking coins out can scratch them. The sliding plastic strip in an album can leave a row of fine lines across a coin.
• If a coin was cleaned years ago, leave it as it is now. More cleaning will not bring the surface back.

Bring them as they are

Bring your coins in as you found them, in their albums, flips, holders, rolls and Mint packaging. Walk in to our Garden Grove store; no appointment needed, and we’ll look at each coin at the counter. If you have a large collection, call first so we can set time aside for it.

Want a figure before you drive? See today’s prices, or photograph your coins just as they are and get a quote from photos.