Best Way to Clean Coins Without Ruining Their Value

Cleaning pennies at home can be a fun and educational activity. It’s important, however, to ensure that the methods you use do not damage the coins or diminish  penny value. Below, we’ll explore safe and effective ways to clean pennies, as well as explain the science behind these techniques.

Image source: PCGS

How to Clean Pennies Without Damaging Them?

 

Do you want to make old dirty coins in your collection look as good as new? Over time, coins can become covered in dirt, grime, and tarnish, but the good news is that you can clean most coins at home using common household products. Before scrubbing your coins, there are a few important things to consider. Keep reading to find the best household hacks for cleaning coins, and how to approach antique collectibles differently.

Materials Needed:

• 4 or more pennies (preferably some minted before 1982)
• Vinegar
• Salt
• Baking soda (optional for an alternative method)
• Lemon juice (optional for another alternative)
• 2 small non-metal bowls
• Soft-bristled toothbrush (optional)
• Paper towels

Why Pennies Tarnish

Over time, pennies develop a dull appearance due to oxidation and dirt accumulation.  Pennies minted before 1982 contain 95% copper, making them more susceptible to visible oxidation, which turns them green or blue-green. Newer pennies, made primarily of zinc with a thin copper coating, may not react as dramatically.

Safe Methods to Clean Pennies

Choosing the right cleaning method is essential to ensure the pennies are cleaned without causing unnecessary damage. The age and material composition of a penny significantly affect how it reacts to cleaning agents. For instance, older pennies made before 1982 contain more copper and may tarnish differently compared to newer pennies with a zinc core. Using gentle and appropriate techniques helps maintain both the appearance and potential  value of the coins.

Method 1: Vinegar and Salt

This method is simple and effective for removing dirt and oxidation without harsh scrubbing.

1. Prepare the Bowls: Place a paper towel in the bottom of each bowl to protect the pennies from direct contact with the surface.
2. Add the Pennies: Place two pennies in each bowl.
3. Create the Cleaning Solution: In Bowl 1, pour in enough vinegar to soak the paper towel. In Bowl 2, mix vinegar with a pinch of salt and stir to dissolve.
4. Observe the Reactions: In Bowl 2, the pennies will start to shine within 30 seconds as the salt and vinegar dissolve the outer layer of grime. Flip the pennies after 30 seconds to ensure even cleaning. Then, rinse with water and dry thoroughly.
5. Check Bowl 1: Let the pennies in Bowl 1 sit for an hour. You’ll notice a green layer forming due to the reaction between copper, oxygen, and vinegar.

Method 2: Baking Soda Paste

Baking soda is an excellent choice for cleaning pennies because it is mildly abrasive, which means it can remove dirt and tarnish without scratching or damaging the penny's surface. Unlike stronger cleaning agents, it doesn’t strip away the copper layer or affect the natural patina that adds character and value to older coins.

1. Create the Paste: Mix a small amount of baking soda with water to form a paste.
2. Apply the Paste: Gently rub the paste onto the pennies using your fingers or a soft-bristled toothbrush. This method works by mechanically removing surface grime without any harsh chemical reactions.
3. Rinse and Dry: Rinse the pennies under running water and dry them with a soft cloth.

For a gentler approach, use baking soda, which is mildly abrasive.

1. Create the Paste: Mix a small amount of baking soda with water to form a paste.
2. Apply the Paste: Gently rub the paste onto the pennies using your fingers or a soft-bristled toothbrush.
3. Rinse and Dry: Rinse the pennies under running water and dry them with a soft cloth.

Method 3: Lemon Juice

Lemon juice contains citric acid, which is effective for cleaning copper.

1. Soak the Pennies: Place the pennies in a small bowl filled with lemon juice for about 5 minutes.
2. Check Progress: Flip the pennies and soak for another 5 minutes if needed.
3. Rinse and Dry: Remove the pennies, rinse them thoroughly, and dry.

The Science Behind the Methods

Oxidation and Patina

• In Bowl 1 (vinegar only), copper reacts with oxygen in the air, forming a blue-green compound called malachite. This process is called oxidation, and it naturally occurs over time when copper is exposed to air and moisture. The malachite layer is what gives older, tarnished pennies their characteristic greenish hue.

Chemical Reactions

• In Bowl 2 (vinegar and salt), the acidic vinegar reacts with the salt to create hydrochloric acid, which breaks down copper oxide. This copper oxide is the layer of tarnish that forms on the penny's surface. The reaction dissolves the copper oxide and exposes the clean copper underneath, making the penny shine. The reaction is particularly effective because the salt increases the conductivity of the solution, allowing the acid to work more efficiently.
• The baking soda method relies on physical abrasion rather than chemical reactions. Baking soda's fine particles act like a gentle scrubbing agent, removing dirt and oxidation without scratching or damaging the coin's surface.
• Lemon juice contains citric acid, which reacts with copper oxide in a similar way to vinegar, dissolving the tarnish and grime effectively. This method is particularly gentle and ideal for coins that require a softer cleaning process.

Oxidation and Patina

• In Bowl 1 (vinegar only), copper reacts with oxygen in the air, forming a blue-green compound called malachite. This process is called oxidation.
• The patina (oxidized layer) provides a natural protective coating for copper.

Chemical Reactions

• In Bowl 2 (vinegar and salt), the acidic vinegar reacts with the salt to create hydrochloric acid. This weak acid dissolves copper oxide and dirt, leaving the penny shiny.
• The baking soda method relies on physical abrasion to remove dirt without a chemical reaction.
• Lemon juice uses citric acid to dissolve grime and oxidation.

Tips to Protect the Value of Pennies

1. Avoid Harsh Chemicals: Cleaning coins with strong acids or abrasives can damage them and lower their collectible value.
2. Handle with Care: Use gloves or hold coins by the edges to prevent oils from your fingers from affecting the surface.
3. Preserve Patina: If the coin is a collector’s item, avoid removing the natural patina, as it can enhance the coin’s value.
4. Consult an Expert: For rare or valuable pennies, consult a coin expert or numismatist before attempting to clean them. Improper cleaning can significantly reduce their value or authenticity.
5. Test First: Try cleaning a less valuable penny to ensure the method works as intended.
6. Avoid Harsh Chemicals: Cleaning coins with strong acids or abrasives can damage them and lower their collectible value.
7. Handle with Care: Use gloves or hold coins by the edges to prevent oils from your fingers from affecting the surface.
8. Preserve Patina: If the coin is a collector’s item, avoid removing the natural patina, as it can enhance the coin’s value.
9. Test First: Try cleaning a less valuable penny to ensure the method works as intended.

 

Cleaning pennies at home can be both entertaining and informative. Whether you’re conducting a science experiment or sprucing up coins for display, these methods allow you to clean pennies safely and effectively without harming their value. However, before cleaning, it's crucial to research a penny's value, especially if it's rare or collectible. The natural patina and wear often contribute to its story and worth, so preserving these features is vital. When in doubt, consult a coin expert to ensure the cleaning process doesn't diminish the coin's value or historical significance.

Cleaning pennies at home can be both entertaining and informative. Whether you’re conducting a science experiment or sprucing up coins for display, these methods allow you to clean pennies safely and effectively without harming their value. Remember, the patina and natural wear of a penny often tell a story, so preserve it when possible!

FAQ

Is it safe to clean pennies?

It is generally not recommended to clean pennies, especially rare or collectible ones, as it can reduce their value. Cleaning can cause scratches and damage to the surface, which may diminish the coin's appeal to collectors.

What is the best way to clean pennies without damaging them?

If you must clean a penny, the gentlest method is using a soft cloth and warm water. Avoid harsh chemicals or scrubbing, as these can damage the coin’s surface. For tarnish, a mixture of mild soap and water can be used.

Can I use vinegar to clean pennies?

Vinegar can be effective for removing heavy tarnish from pennies, but it’s important to be cautious. Soak the penny briefly in vinegar, rinse it with water, and dry it gently to avoid overexposure to acid, which can damage the coin.

How do I remove tarnish from pennies?

Tarnish on pennies can be removed using a mixture of vinegar and salt or baking soda and water. Soak the penny for a short period, then gently rub with a soft cloth. Be careful not to use abrasive materials that could scratch the surface.

What should I use to clean a dirty penny?

For dirty pennies, warm water and a mild soap solution are best. Gently scrub with a soft brush or cloth to remove dirt. Avoid using abrasive tools or chemicals that could scratch or damage the coin.

Is it okay to clean rare or valuable pennies?

No, it is not recommended to clean rare or valuable pennies. Cleaning can strip away the natural patina and surface details, significantly reducing the coin's value. Collectors prefer coins in their original, unaltered state.

Can I clean copper pennies with baking soda?

Yes, baking soda can be used to clean copper pennies. Make a paste by mixing baking soda and water, and apply it to the penny using a soft cloth. Gently rub the paste on the surface, then rinse and dry the penny carefully.

How can I clean old pennies that are turning black?

Blackening on old pennies may indicate tarnish or corrosion. You can try using vinegar and salt or a baking soda paste to remove the blackness. However, if the coin is valuable, it's better to leave it as is to preserve its value.

Should I use a toothbrush to clean pennies?

A toothbrush can be used with caution to clean pennies. Use a soft-bristled toothbrush to gently scrub the penny with a mild soap solution. Avoid scrubbing hard, as this could scratch the coin’s surface.

Will cleaning my pennies decrease their value?

Yes, cleaning pennies can decrease their value, especially if they are rare or collectible. Cleaning can leave scratches, dullness, or remove valuable patina, making the coin less desirable to collectors.

How do I clean a penny without scratching it?

To clean a penny without scratching it, use a very soft cloth or a gentle brush, along with warm water and mild soap. Avoid any abrasive materials, and always clean with care, using minimal pressure.

What household items can I use to clean pennies?

You can use household items such as vinegar, baking soda, mild soap, and warm water to clean pennies. However, always use these sparingly and avoid strong chemicals that could damage the coin.

Can I use soap and water to clean pennies?

Yes, soap and water are safe for cleaning pennies, especially for coins that aren’t highly valuable. Use warm water and a small amount of mild soap, gently scrub with a soft brush or cloth, and dry the penny carefully.

How can I clean a penny with tarnish and make it look shiny again?

To remove tarnish and restore shine, soak the penny in vinegar or a baking soda paste. After soaking, gently rub the coin with a soft cloth, rinse with water, and dry it thoroughly. Avoid over-cleaning to preserve its surface.

Why should I avoid cleaning collectible pennies?

Cleaning collectible pennies can drastically reduce their value. Collectors seek coins in their original condition, and cleaning often removes natural patina and can leave visible scratches, which can make the coin less desirable for purchase or auction.

 

Wheat pennies are among the most sought-after U.S. coins, but identifying the most valuable ones takes time and dedication. Whether you're buying or selling, it's important to make informed decisions.

Error coins, no-mint mark pennies, and low mintage Lincoln cents tend to be the most valuable and are an excellent starting point for those looking to build a high-quality wheat penny collection.

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*This information is for educational purposes only. Bullion Shark is not responsible for any factual errors that may be contained in this post. This information is not intended for investment purposes. Please consult an investment advisor before investing.

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