When considering how to clean a coin with baking soda, it’s crucial to approach the task with a clear understanding of both its potential benefits and significant risks. While baking soda is a readily available household item known for its mild abrasive and deodorizing properties, its application to coins, especially valuable ones, can lead to irreversible damage. This comprehensive guide will delve into the nuances of using baking soda for coin cleaning, highlighting safety precautions, alternative methods, and the paramount importance of preservation over pristine appearance for numismatic items.
Understanding the Risks and Rewards of Cleaning Coins with Baking Soda
Baking soda, chemically known as sodium bicarbonate, is a fine powder that can effectively lift dirt, grime, and light tarnish from various surfaces. For everyday, low-value coins, its abrasive nature can be beneficial in removing superficial layers of dirt. However, this very abrasiveness is its greatest drawback when it comes to coins.
The surface of a coin, particularly an older or collectible one, often possesses a natural patina – a layer of oxidation that develops over time. This patina is not dirt; it’s a protective layer that collectors highly value as evidence of age and authenticity. Aggressive cleaning, even with seemingly mild substances like baking soda, can strip away this patina, leaving the coin looking unnaturally shiny or even damaged. Such damage significantly diminishes a coin’s numismatic (collector’s) value, often rendering it worthless to serious collectors.
Therefore, before you even consider how to clean a coin with baking soda, you must weigh the desire for a cleaner coin against the potential for irreparable harm.
Assess the Coin’s Value Before Cleaning
This step cannot be overstressed. The single most important action to take before attempting any cleaning is to assess the coin’s potential value.
- Is it a common circulation coin? For instance, a modern penny or dime found in your couch cushions is unlikely to hold significant numismatic value. These are the only types of coins for which attempting a baking soda cleaning might be considered, and even then, with caution.
- Is it an older coin, a commemorative coin, or one with a unique error? If there’s any doubt about a coin’s rarity, historical significance, or potential market value, do not clean it. Cleaning can reduce its value by 50% or more, or even render it unsellable to collectors.
- Consult a Professional: If you suspect a coin might be valuable, consult a reputable coin dealer or professional numismatist. They can appraise the coin and advise whether cleaning is appropriate (which it almost never is for valuable coins) or if it should be preserved in its original state. Remember, a dirty but original coin is almost always more valuable than a “cleaned” one.
Handle Coins with Utmost Care
Regardless of whether you intend to clean a coin or not, proper handling is essential. Oils and acids from your skin can react with the coin’s metal, leading to new tarnishing or fingerprints that are nearly impossible to remove.
- Always hold coins by their edges: Use your thumb and forefinger to grip the coin along its rim.
- Wear cotton gloves: For truly valuable or important coins, wear soft, lint-free cotton gloves to prevent any contact between your skin and the coin’s surface.
Cleaning Coins with Baking Soda (For Non-Collectible Coins Only)
If, after careful consideration, you’ve determined that your coin is of low value and you’re willing to accept the risks, you can proceed with caution. The following methods demonstrate how to clean a coin with baking soda for general circulation coins that are not intended for collection.
Method 1: Simple Baking Soda Scrub
This method uses baking soda as a mild abrasive to physically lift dirt.
1. Preparation: Gather your materials: a small bowl, baking soda, water, a soft cloth (microfiber is ideal), and a soft-bristled toothbrush (a child’s toothbrush often works well).
2. Make a Paste: In the small bowl, mix a very small amount of baking soda with just a few drops of water. You want to achieve a thick, consistent paste – not a watery solution. The goal is a consistency similar to toothpaste.
3. Apply and Gently Scrub: Apply a small dab of the baking soda paste to the coin’s surface. Using your soft cloth or the soft-bristled toothbrush, gently scrub the coin. Use very light pressure and circular motions. The key word here is gentle. Avoid aggressive scrubbing, as this is where scratches are most likely to occur. Focus on areas with visible dirt or grime.
4. Inspect and Repeat (if necessary): Periodically rinse a small section of the coin under running water to check your progress. If dirt remains, reapply paste and continue scrubbing gently.
5. Rinse Thoroughly: Once you are satisfied with the cleanliness (or have removed as much as possible without excessive scrubbing), rinse the coin thoroughly under cool, clean running water. Ensure all baking soda residue is completely removed. Any leftover residue can continue to react with the coin’s surface or attract new dirt.
6. Dry Carefully: Pat the coin dry immediately with a soft, lint-free cloth. Do not air dry, as water spots can form. Ensure the coin is completely dry before storing it.
Method 2: Baking Soda and Vinegar Soak (for Very Low-Value Coins)
This method utilizes a chemical reaction to help loosen stubborn dirt. Due to the acidic nature of vinegar, this method carries higher risks and should only be used on very low-value, non-collectible coins, and for very short durations. Vinegar can etch certain metals and strip patinas quickly.
1. Preparation: Gather white distilled vinegar, baking soda, a small non-metal bowl, and a soft cloth.
2. Vinegar Soak (Brief!): Pour a small amount of white distilled vinegar into the non-metal bowl. Dip the coin into the vinegar for a maximum of 30 seconds. For some metals, even this short duration can be too long. Observe the coin closely. If you see any adverse reactions (e.g., rapid discoloration, etching), remove it immediately.
3. Baking Soda Application: Remove the coin from the vinegar. While the coin is still wet with vinegar, immediately sprinkle a generous amount of baking soda directly onto its surface. You will observe a bubbling, fizzing reaction. This effervescence helps to lift dirt and neutralize the vinegar.
4. Gently Scrub: As the reaction occurs, gently rub the baking soda into the coin’s surface with your fingers or a soft brush. The combined action of the chemical reaction and the mild abrasive helps to dislodge grime.
5. Rinse Thoroughly: Immediately after a brief scrub (no more than 15-30 seconds), rinse the coin very thoroughly under cool, clean running water. Ensure all traces of baking soda and vinegar are removed.
6. Dry Carefully: Pat the coin dry immediately with a soft, lint-free cloth. Ensure it is completely dry.
- Important Considerations for Both Methods:*
- Abrasiveness: Remember, baking soda is abrasive. Excessive scrubbing or pressure, even with a soft cloth, can result in microscopic scratches or even visible damage, especially on softer metals like copper or silver.
- Acidity of Vinegar: Vinegar is an acid. Prolonged exposure can etch the coin’s surface, particularly on copper, bronze, or zinc coins. It can also permanently strip away desirable patinas.
- Thorough Rinsing: This is critical. Any residual baking soda or vinegar can continue to react with the coin’s metal over time, leading to further corrosion or discoloration.
- Never Use on Proof Coins: Proof coins have a highly polished, mirror-like surface. Any abrasive, including baking soda, will instantly ruin this finish.
Why “No Cleaning at All” is Often the Best Approach
For valuable, antique, or collectible coins, the consensus among numismatists is clear: do not clean them. The natural dirt and patina that accumulate over decades or centuries are considered part of the coin’s history and character. Collectors value this originality. A “cleaned” coin, even if it looks shinier, is almost always less valuable than an uncleaned one, often significantly so.
Think of it like an antique piece of furniture. While you might dust it, you wouldn’t sand down and refinish a valuable antique unless it was absolutely necessary for structural integrity, as it would destroy its historical value. Coins are similar.
The “Net Value” of Cleaning
Often, people clean coins hoping to reveal a rare date or mint mark, or simply to make them look “better.” However, the act of cleaning almost invariably leads to a net loss in value. The slight improvement in appearance is far outweighed by the damage to the surface and the loss of original character. A coin that might have been worth $100 in its original, dirty state could plummet to $10 or even $1 after being improperly cleaned.
Alternatives for Collectible Coins (When Absolutely Necessary)
While “no cleaning” is the golden rule for valuable coins, there are rare instances where a very gentle, non-abrasive approach might be considered, primarily to remove loose debris that is actively harming the coin (e.g., PVC residue from old flips). These methods are still risky and should be performed by experienced individuals or professionals.
1. Distilled Water Soak: This is the safest method for removing loose dirt or environmental grime.
* Process: Place the coin in a small container of distilled water. Let it soak for several hours, or even a few days, changing the water periodically.
Gentle Brushing: After soaking, if debris remains, gently* brush the coin while it is still submerged in distilled water using an extremely soft, natural-bristle brush (like a camel hair brush). The water acts as a lubricant, reducing friction.
* Drying: Carefully remove the coin and pat it dry with a soft, lint-free cloth.
* Benefit: This method does not involve chemicals or abrasives and is less likely to damage the coin’s surface or patina. It primarily softens and dislodges loose foreign material.
2. Olive Oil Soak (for Copper/Bronze Coins Only): This method is sometimes used to remove “verdigris” (a green, powdery corrosion) from copper or bronze coins.
* Process: Place the copper or bronze coin in a small dish of virgin olive oil. Let it soak for weeks or even months, changing the oil periodically.
* Mechanism: The olive oil is thought to slowly dissolve or displace the verdigris without being overly aggressive on the underlying metal.
* Caution: This is a very slow process, and results are not guaranteed. It can also leave an oily residue that needs to be carefully removed. Not suitable for silver or other metals.
3. Ultrasonic Cleaning (with extreme caution and specific solutions): Ultrasonic cleaners use high-frequency sound waves to create microscopic bubbles that implode, dislodging dirt.
Process: Use only distilled water in the ultrasonic cleaner. A very tiny amount of a specialized, coin-safe neutral detergent might* be added, but this requires professional knowledge.
* Caution: Even with distilled water, the constant vibration can potentially dislodge details or affect the surface over time. This method is generally reserved for professional conservators. Never use harsh chemicals in an ultrasonic cleaner with coins.
Professional Coin Conservation
For truly valuable or historically significant coins, the only recommended course of action for “cleaning” (more accurately, conservation) is to consult a professional numismatic conservator. These experts have specialized knowledge, tools, and chemicals to stabilize and preserve coins without damaging their intrinsic value or historical integrity. Their goal is not to make a coin look “new,” but to prevent further deterioration and remove harmful surface contaminants while preserving the original surface and patina.
Conclusion
Understanding how to clean a coin with baking soda reveals a dichotomy: it’s a simple, effective method for general dirt on common, low-value coins, but a perilous one for anything with numismatic value. The abrasive nature of baking soda, even when used gently, poses a significant risk of scratching or altering a coin’s surface and destroying its valuable patina.
For the vast majority of coins, especially those with any potential collectible or historical significance, the best advice remains simple: do not clean them. Embrace the coin’s natural state and history. If you must attempt a cleaning on a non-collectible coin, proceed with extreme caution, gentleness, and a clear understanding of the risks involved. When in doubt, consult a professional numismatist to ensure the preservation of your coin’s true value.
Does Dawn dish soap clean pennies?
Thanks for asking. Especially bright copper. If you have to use anything to try and get some gunk.
Is it okay to clean silver with baking soda and vinegar?
I can help with that. Put the silver items in a bowl of appropriate size and cover them with white distilled vinegar. Add baking soda into the bowl – the approximate proportions are 4 tablespoons of baking soda for every cup of vinegar. Leave the silver in the mixture for 1 hour. Rinse with clean water and dry well with soft cotton cloth.
What not to clean coins with?
Don’t use metal polish – This might seem like one of the most obvious ways to clean coins. After all, they’re made of metal. But these cleaners are often made with caustic chemicals that can do serious, and permanent, damage to a coin. Don’t use toothpaste – Toothpaste is extremely abrasive.