When people ask if their coin is cleaned, or question hobbyists who say their coin is cleaned, many collectors do not know exactly why. This article explains what is known as destructive cleaning.
These methods permanently alter the coin’s surface and dramatically reduce its collectible value.
Dipping: Using a chemical solution (often a dilute acid) to strip away toning or oxidation from the coin’s surface, leaving micro bubbles that are red flags.
Smoothing: Using a cloth, abrasive paste or other substance to rub the surface, leaving tiny scratches called “hairlines.”
Polishing: Using a device or tool to buff the surface of the coin so that it shines with a false luster, often blurring devices.
Whizzing: Using a high-speed rotating brush to create artificial luster, leaving unnatural proof-like sheen with telltale patterns of metal flow around the coin’s devices.
Scrubbing: A coin that contains evidence of an abrasive material like baking soda or a metal brush, often to remove verdigris or other contaminant.
Chemical Application: Soaking a coin in acidic household items like vinegar with salt or lemon juice that remove verdigris and ruin eye appeal.
Electrolysis: Using electrical current in a solution to strip away corrosion, a process often used on ancient coins or ones found by metal detecting.
All sample coins above would get a details/cleaned grade by a holdering company.
For those who want to clean coins via non-destructive methods, consider rinsing them in distilled water or soaking in acetone, mild soap or olive oil. To learn more about if and when to clean coins, see “When, If and How to Clean Coins.”
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