Cleaning coins can be a tempting proposition. A dull, tarnished coin might seem to benefit from a little sprucing up. However, cleaning coins, especially valuable or collectible ones, can be a risky undertaking. Improper cleaning can drastically reduce their value and aesthetic appeal. This guide will explore the safest and most effective methods for cleaning coins, emphasizing prevention and gentle techniques.
Understanding the Risks of Cleaning Coins
The primary reason to avoid cleaning coins is the potential for irreversible damage. A coin’s patina, the natural toning that develops over time, is often considered desirable by collectors. Cleaning can remove this patina, leaving the coin with an unnatural, sterile appearance known as “whizzing.” This process can also create microscopic scratches that significantly lower the coin’s grade and value.
Harsh chemicals or abrasive materials can further damage a coin’s surface, altering its original luster and texture. Once a coin is damaged, there’s usually no way to restore it to its original condition. Therefore, caution and restraint are paramount.
The Collector’s Perspective
Collectors generally prefer original, uncleaned coins. The presence of original mint luster, a subtle sheen visible on uncirculated coins, is highly valued. Cleaning removes this luster, making the coin less desirable. A coin’s grade, a measure of its condition, directly impacts its value. Cleaning can negatively affect this grade, resulting in a substantial financial loss.
When Cleaning Might Be Considered
There are limited circumstances where cleaning a coin might be acceptable. For instance, if a coin is heavily encrusted with dirt or debris that obscures its features, gentle cleaning might be necessary to identify it properly or prevent further damage from corrosive substances. However, even in these cases, extreme caution is essential. Coins found during metal detecting may require some cleaning to aid in identification.
Preventative Measures: The Best Approach
The best way to “clean” coins is to prevent them from getting dirty in the first place. Proper storage and handling are crucial for preserving their condition.
Proper Storage Techniques
Coins should be stored in archival-quality holders that protect them from environmental factors such as moisture, air, and pollutants. Avoid storing coins in PVC (polyvinyl chloride) holders, as they can leach harmful chemicals that damage the coin’s surface over time.
Acid-free paper envelopes, cardboard coin holders with Mylar windows, and plastic coin capsules are all suitable options. For long-term storage, consider using a climate-controlled environment with stable temperature and humidity levels.
Handling Coins Correctly
Always handle coins by their edges to avoid transferring oils and dirt from your fingers to the surface. Consider wearing cotton gloves to further minimize the risk of contamination. Avoid touching the coin’s face, as this is where details are most vulnerable to wear and damage.
Gentle Cleaning Methods: Proceed with Caution
If you decide that cleaning a coin is necessary, start with the gentlest methods possible and proceed with extreme caution. Always test the cleaning method on a less valuable coin of similar composition and condition first.
The Soap and Water Method
This is the safest method for removing loose dirt and debris. Use distilled water and a mild, pH-neutral soap, such as dish soap without any added perfumes or dyes. Gently rub the coin between your fingers or use a soft-bristled brush (like a new toothbrush) to dislodge dirt. Rinse the coin thoroughly with distilled water and pat it dry with a soft, lint-free cloth.
Avoid rubbing the coin too vigorously, as this can create scratches. Never use abrasive cleaners or scouring pads.
Soaking in Distilled Water
For coins with more stubborn dirt, soaking them in distilled water for several hours or even overnight can help loosen the debris. Change the water periodically. After soaking, gently rinse the coin and pat it dry.
Acetone Cleaning
Acetone is a solvent that can remove organic contaminants such as grease, oil, and fingerprints. It’s generally safe for most coins, but should still be used with caution. Work in a well-ventilated area and wear gloves to avoid skin contact.
Submerge the coin in acetone for a few minutes, then remove it and let it air dry. Do not rub the coin. Repeat the process if necessary. Acetone will not remove tarnish or oxidation.
Olive Oil Soak (for specific cases)
In some cases, particularly for coins encrusted with hard deposits, a prolonged soak in olive oil can be effective. Use only pure, unadulterated olive oil. Submerge the coin for several weeks or even months, checking periodically for progress. The oil will slowly penetrate and soften the deposits.
After soaking, gently remove the coin and rinse it with warm water and a mild soap. Use a soft brush to remove any remaining debris. This method is slow and requires patience, but it can be effective for removing stubborn encrustations without damaging the coin. Be aware that some collectors dislike the appearance of coins cleaned with olive oil, as it can sometimes leave a slightly oily residue.
Methods to Avoid: Harmful Techniques
Many cleaning methods are highly damaging and should be avoided at all costs. These include:
- Abrasive cleaners: Products like metal polishes, scouring pads, and toothpaste are far too harsh for coins and will scratch the surface.
- Vinegar or lemon juice: These acidic substances can etch the coin’s surface and remove the patina.
- Baking soda: While baking soda is mildly abrasive, it can still scratch the coin, especially if used vigorously.
- Commercial coin cleaners: Many commercial coin cleaners contain harsh chemicals that can damage the coin. Research any product thoroughly before using it, and always test it on a less valuable coin first.
- Electrolysis: This method involves using an electric current to remove tarnish and corrosion. While it can be effective, it’s also risky and can easily damage the coin if not performed correctly. It’s best left to professionals.
Dealing with Specific Types of Coins
The appropriate cleaning method depends on the coin’s metal composition and the type of contamination.
Silver Coins
Silver coins are prone to tarnishing due to their reaction with sulfur in the air. If cleaning is deemed necessary, start with the soap and water method or acetone cleaning. For more severe tarnish, consider using a silver dip specifically designed for coins. However, use these dips sparingly and follow the instructions carefully, as they can easily over-clean the coin.
Copper Coins
Copper coins can develop a green patina called verdigris, which is a form of corrosion. Verdigris can be difficult to remove without damaging the coin. A long soak in olive oil is often the best option. Avoid using harsh chemicals or abrasive cleaners.
Gold Coins
Gold coins are relatively inert and resistant to corrosion. They usually only require a gentle cleaning with soap and water to remove dirt and fingerprints. Avoid using any abrasive cleaners, as even minor scratches can detract from their value.
Base Metal Coins
Base metal coins, such as those made of nickel or copper-nickel alloys, can be cleaned using the soap and water method or acetone. Avoid using harsh chemicals or abrasive cleaners.
Professional Coin Cleaning Services
If you have valuable or rare coins that require cleaning, consider consulting a professional coin conservator. These experts have the knowledge, skills, and equipment to clean coins safely and effectively without damaging them.
They can assess the coin’s condition, determine the best cleaning method, and perform the work with minimal risk. While professional cleaning services can be expensive, they may be worth the investment for preserving the value of your coins.
After Cleaning: Proper Handling and Storage
After cleaning a coin, it’s essential to handle and store it properly to prevent further contamination or damage.
Rinse the coin thoroughly with distilled water to remove any traces of cleaning agents. Pat the coin dry with a soft, lint-free cloth. Avoid rubbing the coin, as this can create scratches.
Store the coin in an archival-quality holder that protects it from environmental factors. Handle the coin by its edges to avoid transferring oils and dirt from your fingers.
Final Thoughts
Cleaning coins is a risky undertaking that can significantly reduce their value. Prevention is the best approach. Proper storage and handling are crucial for preserving the condition of your coins. If cleaning is necessary, start with the gentlest methods possible and proceed with extreme caution. Avoid using harsh chemicals or abrasive cleaners. When in doubt, consult a professional coin conservator. Remember that a coin’s original patina is often desirable, and removing it can detract from its value and aesthetic appeal. The key is to clean as little as possible, and only when absolutely necessary.
What are the most common mistakes people make when cleaning coins?
One of the most frequent errors is using overly abrasive cleaning methods. Harsh chemicals like bleach or strong acids, along with abrasive materials such as scouring pads or rough cloths, can scratch the surface of the coin, removing its original luster and detail. This damage significantly reduces the coin’s value, especially for collectible pieces. Another common mistake is excessive rubbing or scrubbing, even with softer materials. This action can still create microscopic scratches, diminishing the coin’s appeal and numismatic worth.
Another significant error is improper drying techniques. Leaving coins to air dry after cleaning can result in water spots and further tarnishing, particularly if the water contains minerals or impurities. Using a hair dryer or other heat source can also be detrimental, potentially altering the coin’s color and causing irreversible damage. It is essential to use a gentle and controlled drying method, such as patting the coin dry with a soft, lint-free cloth, to prevent these problems.
Which cleaning methods are considered safest for delicate or valuable coins?
For delicate or valuable coins, the safest approach is often to start with the gentlest method possible. This typically involves soaking the coin in distilled water for an extended period, perhaps several hours or even overnight. This allows any loose dirt or debris to soften and detach from the coin’s surface without the need for abrasive cleaning. You can then carefully rinse the coin with more distilled water and gently pat it dry with a soft, lint-free cloth.
If distilled water alone is insufficient, you can consider using a mild soap solution, such as dish soap diluted in distilled water. Ensure the soap is pH-neutral and free of any harsh chemicals or additives. Submerge the coin in the solution for a short time, gently agitating it to loosen any remaining dirt. Again, rinse thoroughly with distilled water and carefully pat dry. Avoid rubbing or scrubbing the coin, as this can still cause damage, especially to coins with delicate surfaces or intricate designs.
Can you use household items like vinegar or lemon juice to clean coins?
While vinegar and lemon juice are sometimes suggested as coin cleaning agents, their use is generally discouraged, especially for valuable or historical coins. These substances are acidic and can react with the metal of the coin, potentially etching the surface and removing fine details. Even a brief exposure can cause noticeable damage, permanently altering the coin’s appearance and reducing its value.
The risk of over-cleaning or etching the coin’s surface is particularly high with these acidic solutions. The acid can dissolve the tarnish or patina unevenly, resulting in an unnatural and unattractive appearance. Furthermore, the reaction between the acid and the coin can create unwanted chemical compounds that can further corrode or damage the metal over time. It’s best to stick to safer and more controlled methods, like distilled water or mild soap solutions, to avoid irreversible damage.
How does cleaning affect the value of a coin?
Cleaning coins, particularly valuable or collectible ones, can significantly diminish their value. Collectors generally prefer coins in their original, uncleaned condition, even if they have some tarnish or wear. Cleaning often removes the natural patina, a thin layer of oxidation that forms over time and is considered a desirable characteristic by many numismatists. The removal of this patina can make the coin appear unnatural and less appealing.
Furthermore, cleaning can leave behind microscopic scratches or other imperfections that are easily visible under magnification. These imperfections are considered damage and can drastically reduce the coin’s grade, thereby lowering its market value. In some cases, a cleaned coin may be worth significantly less than an uncleaned one, even if the uncleaned coin has more visible dirt or tarnish. Therefore, it’s generally advisable to avoid cleaning valuable coins unless you are a professional numismatist or have specific expertise in coin conservation.
What is the best way to remove stubborn dirt or grime from a coin without scratching it?
For stubborn dirt or grime, prolonged soaking in distilled water remains the safest first step. If that’s insufficient, consider using a wooden toothpick or a soft brush (like a camel hair brush) very gently to dislodge the dirt. The key is to apply minimal pressure and to avoid rubbing or scrubbing. The goal is to loosen and lift the dirt particles without causing any abrasion to the coin’s surface.
Another option is to use a specialized coin cleaning solution designed specifically for removing grime. These solutions are typically formulated to be non-abrasive and safe for use on various coin metals. However, it’s crucial to follow the manufacturer’s instructions carefully and to test the solution on an inconspicuous area of the coin first to ensure it doesn’t cause any discoloration or damage. Always rinse the coin thoroughly with distilled water after using any cleaning solution and pat it dry with a soft, lint-free cloth.
Are there specific types of coins that should never be cleaned?
Yes, there are certain types of coins that should almost always be left uncleaned. These include rare or valuable coins, especially those with historical significance. The patina on these coins is often a sign of their age and authenticity, and removing it can drastically reduce their value and desirability among collectors. Coins with numismatic value should be handled with extreme care, and cleaning should generally be avoided unless you are a trained professional.
Additionally, coins with delicate surfaces, such as those made of soft metals like silver or copper, are particularly susceptible to damage from cleaning. Even gentle cleaning methods can leave behind scratches or other imperfections that can diminish their value. Proof coins, which are specially struck and have a mirror-like finish, should also never be cleaned, as any cleaning will inevitably damage their pristine surface. In these cases, it’s best to consult with a professional numismatist before attempting any cleaning.
How should coins be stored after cleaning to prevent further tarnishing?
Proper storage is crucial to prevent cleaned coins from re-tarnishing. The most effective way to protect coins is to store them in individual, inert holders or albums specifically designed for coin collecting. These holders are made of materials that won’t react with the coin’s metal and are often airtight or close to airtight, preventing exposure to air and moisture. Avoid storing coins in PVC holders, as PVC can degrade over time and release harmful chemicals that can damage the coin’s surface.
Furthermore, store coins in a cool, dry place with stable temperatures. Fluctuations in temperature and humidity can accelerate tarnishing. Consider using desiccant packs in the storage area to absorb any excess moisture. Handling coins with clean, dry hands or wearing cotton gloves can also help prevent the transfer of oils and other contaminants that can contribute to tarnishing. Regular inspection of your coin collection is recommended to identify and address any potential storage issues early on.