Whether cleaning coins can increase their value is a controversial topic among coin collectors and dealers. There are pros and cons to cleaning coins that need to be considered when determining if cleaning will add value.
The case for cleaning coins
Here are some reasons why some argue cleaning coins can increase value:
- Removes dirt, oil, and tarnish – Cleaning can remove surface gunk like dirt, oil, and tarnish that builds up on coins over time. This allows the original luster and shine of the coin to show through.
- Reveals details – Cleaning can reveal intricate details on the coin’s surface that are obscured by dirt and tarnish.
- Improves eye appeal – A shiny, lustrous coin is more visually appealing than a dark, tarnished one to many collectors.
- Higher grades – Coins that have been properly cleaned can sometimes get higher grades from third-party grading services because their surfaces are cleaner.
Proponents argue cleaning can make a coin look more attractive and potentially earn it a higher price. For example, an uncirculated coin pulled from a mint set may have some light fingerprints or spotting that could be removed through professional cleaning to make it look perfect.
The case against cleaning coins
Here are some cons that argue cleaning coins can damage value:
- Permanently alters surfaces – Cleaning can permanently scratch, polish, or oxidize the surfaces of coins.
- Removes original patina – The toning and patina that naturally forms on coins over decades is removed by cleaning.
- Damages integrity – Cleaning is considered altering the original surface and integrity of a coin.
- Lower grades – Coins with cleaned surfaces often get lower grades from third-party graders.
Opponents argue that cleaning permanently damages coins and lowers their value for collectors. Even slight hairlines, scratches, or changes in luster from improper cleaning can significantly reduce the grade and value of rare coins. Valuable toning and patina is also stripped away.
Professional vs. amateur cleaning
There is an important distinction between professional and amateur cleaning:
- Professional – Reputable professional coin dealers or conservationists have the knowledge, skills, and tools to properly clean coins without damaging them. This involves delicate techniques like dipping and precision tools.
- Amateur – Inexperienced collectors cleaning coins at home can permanently damage them using harsh chemicals, abrasives, and improper methods.
Most warnings about cleaning coins are focused on collectors attempting cleaning amateurishly at home. This can and often does permanently damage coins.
Should valuable coins be cleaned?
For extremely rare and valuable coins, most experts recommend against cleaning them. Here are some guidelines on cleaning valuable coins:
- Do not clean – Leave circulating coins, proofs, and collector coins in their natural state.
- Consult an expert – Have a reputable dealer or professional determine if cleaning is advisable for very high value coins.
- Light cleaning only – At most, employ very light cleaning techniques to remove obvious surface contaminants on rare coins.
Cleaning rare coins is controversial even among professionals. Valuable coins that survived decades or longer uncleaned should generally remain unaltered.
What can be safely cleaned?
While valauable coins are best left uncleaned, some coins can be safely cleaned to improve their appearance. Coins that can potentially benefit from careful professional cleaning include:
- Lower grade circulated coins
- Heavily tarnished silver coins
- Ancient coins recovered from the ground
- Coins stuck together by debris or residues
For common, lower value coins with heavy dirt or tarnish, careful cleaning by a professional can sometimes improve their appearance without damaging them further. But even circulated coins should be evaluated before cleaning to avoid removing original patina.
How to safely clean coins
For coins that can benefit from cleaning, proper techniques and care are essential. Here are some safe cleaning tips:
- Use mild soap and water – For many coins, a light soak and gentle scrub with soap and water is sufficient to remove dirt and oils without damaging the surfaces.
- Acetone bath – An acetone bath can safely remove oils and organic residues. Avoid oversoaking.
- Distilled water rinse – Rinse coins thoroughly in distilled water after cleaning to remove any solutions that could continue reacting.
- Soft brush – Use a very soft toothbrush or jewelry brush to gently dislodge built-up grime.
- Soft cloth – Polish carefully with a microfiber cloth once dirt is removed.
Harsh chemicals and abrasives that can scratch coins including baking soda, jewelers rouge, and rock tumbling should be avoided. Be gentle and patient when cleaning valuable coins.
The value of uncleaned coins
For rare and collectible coins, leaving them uncleaned or with natural patina intact often preserves far more value than attempting to clean them. Here are some reasons uncleaned coins can be highly valued:
- Original surfaces – Collectors prized unaltered surfaces, even with tarnish and wear.
- Provenance – An uncleaned history proves the coin’s authenticity.
- Patina – Beautiful natural blue, red, and rainbow hues.
- Higher grades – Uncleaned coins can achieve higher grading up to MS70.
- Historical value – Provides a glimpse into the coin’s untampered past.
Many collectors specifically seek coins with beautiful natural toning, patina, and original old surfaces. Cleaning strips away this history and reduces desirability.
Grading considerations
Third-party coin grading services like PCGS, NGC, and ANACS assign grades based on how much a coin’s surfaces have been altered. Here are some grading considerations with cleaned coins:
- Details grade – Coins determined to be cleaned will get a “details” grade like AU Details, indicating it has been cleaned.
- Partial reduction – Light cleaning may only drop a coin by one grade level.
- Complete reduction – Harsh cleaning could reduce an Uncirculated coin to a Very Fine details grade.
- Scratches – Any scratches from cleaning may further reduce the grade.
Graders can usually identify cleaned surfaces, even if the untrained eye cannot. This can significantly reducecollector value and auction prices.
Resale value of cleaned coins
The resale market for coins considers cleaning and surface alterations negatively. Here is how cleaning typically affects resale value:
- 30-50% reduction – Price guides note cleaned coins trade at a discount.
- Details grade – Coins in holders with details grades due to cleaning have lower prices.
- Damaged status – Buyers avoid coins noted as “cleaned” or “damaged”.
- No premium – Cleaned coins fail to earn premium prices relative to condition.
On the retail and auction market, cleaned coins almost always trade at significant discounts relative to their technical grade. Significant value can be lost trying to clean valuable coins.
Cleaning vs. conservation
There are important differences between cleaning coins to enhance their appearance versus professional conservation to stabilize them:
- Cleaning alters – Aims to improve appearance by removing toning, patina, and wear.
- Conservation preserves – Seeks to stabilize coins against further deterioration.
- Improper cleaning damages – Harsh methods leave scratches, hairlines, and other damage.
- Conservation is non-destructive – Gentle techniques are used that do not alter surfaces.
Reputable professional numismatic conservation seeks to preserve coins in their current state rather than alter their surfaces. Cleaning aims to change a coin’s appearance while conservation aims to preserve it.
Conclusion
Cleaning coins is a controversial topic filled with nuance. While cleaning can improve the appearance of some lower value coins, it almost universally reduces collector value and desirability of rare coins. Valuable coins with natural patina intact are preferred and command higher prices over harshly cleaned examples in the numismatic market. Light cleaning should only be attempted with caution using proper techniques to avoid permanent damage that is difficult to discern.