Coin collecting is a fascinating hobby that connects enthusiasts with history, artistry, and monetary heritage. However, one of the most debated topics among numismatists is whether or not to clean coins. Understanding how to clean coin collection properly is crucial for preserving both the physical integrity and monetary value of your precious coins.
The decision to clean coins is far more complex than it initially appears. While the temptation to restore a tarnished coin to its original brilliance is understandable, the reality is that cleaning can have serious consequences for your collection’s value and authenticity.
The Fundamental Rule: When in Doubt, Don’t Clean
The golden rule in numismatics is simple: never clean valuable coins unless absolutely necessary. This principle exists because cleaning can irreversibly damage a coin’s surface and dramatically reduce its collectible value. Most professional numismatists and experienced collectors agree that coins should remain in their natural state whenever possible.
The patina, toning, and even dirt that accumulates on coins over time is considered part of their historical character. These natural changes tell the story of the coin’s journey through time and are often valued by collectors as much as the coin itself.
Understanding the Risks of Cleaning Coins
Dramatic Value Reduction
Cleaning can drastically reduce a coin’s numismatic value, sometimes by 50% or more. Collectors and dealers typically prefer coins in their original, untouched condition. The natural toning and patina that develop over decades or centuries are considered desirable characteristics that speak to the coin’s authenticity and age.
When you clean a coin, you’re essentially erasing this historical record. Even if the cleaning makes the coin appear more attractive to the untrained eye, experienced collectors will immediately recognize the signs of cleaning and may view the coin as damaged or altered.
Surface Damage Concerns
Surface damage is a major concern when learning how to clean coin collection items. Even the gentlest cleaning methods can leave microscopic scratches that are invisible to the naked eye but clearly visible under magnification. These hairline scratches can significantly impact the coin’s grade and, consequently, its value.
Professional grading services use high-powered magnification to examine coins, and they can easily detect signs of cleaning. Coins that show evidence of cleaning will receive lower grades, which directly impacts their marketability and monetary worth.
Professional Grading Penalties
Professional grading services penalize cleaned coins by assigning lower grades or even refusing to grade them altogether. Services like PCGS (Professional Coin Grading Service) and NGC (Numismatic Guaranty Corporation) have strict standards regarding cleaned coins.
A coin that might have received a grade of MS-65 in its natural state could drop to MS-60 or lower if it shows signs of cleaning. This grade reduction can mean the difference between a coin worth hundreds of dollars and one worth significantly less.
When Professional Consultation is Essential
If you possess valuable or potentially valuable coins, it’s strongly recommended to consult with a professional numismatist or coin expert before attempting any cleaning or conservation techniques. Professional conservators have access to specialized equipment and techniques that can address specific issues without causing damage.
Professional conservation services may be able to remove harmful residues, environmental damage, or specific types of contamination without resorting to abrasive methods. These experts understand the delicate balance between preservation and maintaining a coin’s original character.
Identifying Valuable Coins
Before considering any cleaning method, it’s crucial to identify which coins in your collection might have significant value. Factors that contribute to a coin’s value include:
- Rarity and mintage numbers
- Historical significance
- Condition and grade
- Metal content (silver, gold, platinum)
- Age and provenance
- Mint errors or varieties
If you’re unsure about a coin’s potential value, have it appraised by a professional before attempting any cleaning procedures.
Safe Cleaning Methods for Low-Value Coins
While cleaning valuable coins is generally discouraged, there are situations where gentle cleaning of common, low-value coins might be acceptable. However, even these methods should be approached with extreme caution.
Gentle Rinsing Technique
For coins with surface dirt that have little to no numismatic value, a gentle rinse in distilled or deionized water may be acceptable. This method should only be used on modern coins or heavily circulated pieces with minimal collector value.
Steps for gentle rinsing:
- Use only distilled or deionized water
- Hold the coin by its edges
- Gently rinse under a slow stream of water
- Avoid rubbing or scrubbing the surface
- Allow dirt to wash away naturally
What to Avoid
Avoid harsh chemicals or abrasives at all costs. Never use:
- Household cleaners
- Jewelry cleaning solutions
- Baking soda
- Toothpaste
- Metal polish
- Abrasive cloths or brushes
- Ultrasonic cleaners
These substances and tools can cause irreversible damage to coin surfaces, including chemical reactions, scratching, and removal of original mint luster.
Proper Drying Technique
After any water contact, pat the coin dry gently with a soft, lint-free cloth. Never rub or wipe the coin surface, as this can cause scratching. Instead, use a dabbing motion to absorb moisture without applying pressure to the coin’s surface.
Essential Handling Techniques
Proper handling is just as important as knowing how to clean coin collection items safely. Correct handling techniques can prevent the need for cleaning in the first place.
Edge Handling Protocol
Always handle coins by their edges to minimize contact with the coin’s surface and prevent fingerprints. Human skin contains oils, acids, and salts that can cause permanent damage to coin surfaces over time. The edges of coins are less critical to their numismatic value and provide a safe grip point.
Protective Gloves
Wear cotton or nitrile gloves when handling valuable coins to avoid transferring oils and dirt from your hands to the coin’s surface. Cotton gloves are preferred for most situations, while nitrile gloves offer better grip and protection against moisture.
Avoid latex gloves, as they can contain sulfur compounds that may react with certain metals over time.
Safe Work Environment
Work over a soft surface when handling coins. Use a soft cloth, felt pad, or foam surface to cushion any accidental drops and prevent damage. This simple precaution can save valuable coins from costly damage due to drops or impacts.
Optimal Storage Solutions
Proper storage is the best way to minimize the need for cleaning and preserve your coin collection’s condition long-term.
Appropriate Storage Materials
Use acid-free and PVC-free holders to store coins safely. Recommended storage options include:
- Mylar flips
- Hard plastic capsules
- Acid-free cardboard holders
- Inert plastic tubes
- Museum-quality storage boxes
Avoid storage materials that contain PVC, as this plastic can release harmful chemicals that cause permanent damage to coins over time.
Environmental Control
Maintain a stable environment for your coin collection. Ideal storage conditions include:
- Temperature: 65-70°F (18-21°C)
- Humidity: 45-55% relative humidity
- Air circulation: Good ventilation without direct airflow
- Light exposure: Minimal UV light exposure
Fluctuations in temperature and humidity can cause expansion and contraction of metals, potentially leading to surface damage or accelerated toning.
Security Considerations
Consider a safe or bank deposit box for valuable collections. Secure storage protects against theft, fire, flood, and other potential disasters. When choosing storage location, consider:
- Fire resistance
- Flood protection
- Security features
- Insurance coverage
- Accessibility for regular inspection
Alternative Preservation Methods
Instead of cleaning, consider these preservation alternatives:
Professional Conservation
Professional conservators can address specific issues like:
- Removing harmful environmental deposits
- Stabilizing active corrosion
- Addressing PVC damage
- Removing adhesive residues
Protective Encapsulation
Encapsulating coins in professional holders can:
- Prevent further environmental damage
- Allow safe handling and viewing
- Maintain current condition
- Provide authentication
Building Good Collection Habits
Developing proper collection management habits prevents many cleaning-related issues:
Regular Inspection
Conduct regular, gentle inspections of your collection to identify potential problems early. Look for:
- Signs of corrosion
- Environmental damage
- Storage material degradation
- Pest activity
Documentation
Maintain detailed records of your collection, including:
- Acquisition dates and sources
- Condition assessments
- Storage locations
- Any conservation treatments
Education and Research
Continuously educate yourself about proper numismatic practices through:
- Professional organizations
- Numismatic publications
- Collector forums and communities
- Educational seminars and workshops
Conclusion
Learning how to clean coin collection items properly is fundamentally about understanding when not to clean. The primary goal should always be preservation, not restoration. The natural aging, toning, and patina that develop on coins over time are integral parts of their numismatic character and value.
For valuable or potentially valuable coins, professional consultation is always the safest approach. When dealing with common, low-value coins that require cleaning, use only the gentlest methods possible, and always err on the side of caution.
Remember that proper handling, storage, and environmental control are far more important than cleaning in maintaining your collection’s condition and value. By following these guidelines and respecting the historical integrity of your coins, you’ll ensure that your collection remains a source of enjoyment and potential investment for years to come.
If you’re ever unsure about the best approach for a specific coin, it’s always best to consult with a professional numismatist rather than risk damaging an irreplaceable piece of history.
Are you supposed to clean your coin collection?
While you may be tempted to polish your coins to make them look shiny and new, proceed with caution. Polishing and/or cleaning coins can reduce their value. Older coins that show deep age coloration are more desirable than coins whose surfaces have been stripped away by improper polishing or cleaning.
What do coin dealers use to clean coins?
The coin is dipped into a dilute acid solution that removes the oxidation from the coin along with a small amount of metal. Overdipped coins result in loss of luster which lowers the coin’s grade and appeal. According to author Thomas E. Hudgeons Jr., this is the safest way commonly found coins are cleaned.