Pennies, those humble copper-clad coins we often overlook, can accumulate a surprising amount of grime and tarnish over time. Whether you’re a coin collector looking to restore some luster, a teacher demonstrating a fun science experiment, or simply someone who wants to make those pennies in your jar a little more presentable, knowing the easiest way to clean a penny is a valuable skill. This comprehensive guide explores several methods, focusing on ease, safety, and effectiveness.
Understanding Penny Dirt: What Are We Fighting?
Before diving into cleaning methods, it’s essential to understand what we’re trying to remove. A tarnished penny isn’t just “dirty” in the common sense. The dullness and discoloration are primarily caused by a chemical reaction called oxidation.
Copper reacts with oxygen in the air, forming copper oxide on the surface of the penny. This copper oxide is what gives pennies their characteristic dull, brownish, or even greenish appearance. Fingerprints, oils, and other environmental pollutants can also contribute to the buildup of grime and exacerbate the tarnishing process.
The type of “dirt” will influence the best cleaning approach. Simple surface grime can often be removed with gentle methods, while heavier oxidation requires a slightly more aggressive, yet still careful, approach.
The Vinegar and Salt Method: A Classic and Simple Solution
The vinegar and salt method is arguably the most popular and accessible way to clean pennies. It relies on a simple chemical reaction to dissolve the copper oxide.
Why It Works
Vinegar is a mild acid (acetic acid). The acid in the vinegar reacts with the copper oxide, breaking it down. The salt (sodium chloride) acts as an abrasive and also helps to accelerate the reaction. The chloride ions from the salt help dissolve the copper oxide more effectively. The combination of vinegar and salt creates a potent, yet relatively safe, cleaning solution.
How to Do It: Step-by-Step
- Gather your materials: You’ll need white vinegar (plain distilled vinegar is best), table salt, a small bowl or container, pennies, and a clean cloth or paper towel.
- Prepare the solution: Pour about 1/4 cup of vinegar into the bowl. Add about a teaspoon of salt and stir until the salt is completely dissolved.
- Submerge the pennies: Place the pennies into the vinegar and salt solution, ensuring they are fully submerged.
- Observe the reaction: You should start to see the pennies become brighter almost immediately. The amount of time required will vary depending on the level of tarnish.
- Remove and rinse: After about 1-5 minutes (check frequently), remove the pennies from the solution. Do not leave them in the solution for extended periods, as this can damage the coin’s surface. Rinse the pennies thoroughly with water.
- Dry the pennies: Pat the pennies dry with a clean cloth or paper towel.
Important Considerations
- Time is key: Leaving the pennies in the solution for too long can cause excessive cleaning and potentially damage the coin. Check frequently and remove them as soon as they reach the desired level of cleanliness.
- Gentle touch: Avoid scrubbing the pennies while they are in the solution. This can scratch the surface.
- Water quality: Use clean, preferably distilled or filtered, water for rinsing to avoid reintroducing minerals that could cause further discoloration.
Lemon Juice and Salt: A Natural Alternative
Lemon juice, like vinegar, is a mild acid (citric acid). It works on the same principle as the vinegar and salt method, dissolving the copper oxide.
Advantages of Lemon Juice
- Natural and readily available: Lemons are a common household item and are a natural alternative to vinegar.
- Pleasant scent: Lemon juice has a more pleasant smell than vinegar, which can be a plus for some.
How to Use Lemon Juice
The process for cleaning pennies with lemon juice and salt is virtually identical to the vinegar and salt method. Simply substitute the vinegar with an equal amount of lemon juice. Follow the same steps, keeping a close eye on the pennies and removing them when they reach the desired level of cleanliness.
Lemon Juice Tips
- Freshly squeezed lemon juice is generally preferred, but bottled lemon juice can also be used.
- Ensure the salt is fully dissolved in the lemon juice before adding the pennies.
Ketchup: A Surprisingly Effective Cleaner
Believe it or not, ketchup can also be used to clean pennies. Ketchup contains acetic acid (from the vinegar used in its production) and other acids that can help dissolve copper oxide.
Why Ketchup Works
The acids in ketchup, combined with its slightly abrasive texture, make it a surprisingly effective penny cleaner.
How to Clean Pennies with Ketchup
- Apply the ketchup: Cover the pennies with a generous amount of ketchup.
- Let it sit: Allow the ketchup to sit on the pennies for about 5-10 minutes.
- Rinse and dry: Rinse the pennies thoroughly with water and dry them with a clean cloth or paper towel.
Ketchup Considerations
- The effectiveness of ketchup can vary depending on the brand and its acidity.
- Be sure to rinse the pennies thoroughly to remove all traces of ketchup, as the sugar in ketchup can attract dirt and insects.
Baking Soda Paste: A Gentle Abrasive
Baking soda (sodium bicarbonate) is a mild abrasive that can help remove surface grime and tarnish from pennies.
How to Make and Use Baking Soda Paste
- Create the paste: Mix baking soda with a small amount of water to form a thick paste.
- Apply the paste: Apply the paste to the pennies.
- Gently rub: Gently rub the paste onto the pennies using your fingers or a soft cloth. Avoid applying too much pressure.
- Rinse and dry: Rinse the pennies thoroughly with water and dry them with a clean cloth or paper towel.
Baking Soda Tips
- Baking soda is a gentle abrasive, making it suitable for cleaning pennies without causing significant damage.
- Use a soft cloth to avoid scratching the surface of the coins.
Dish Soap and Water: For Light Cleaning
For pennies with only light surface grime, a simple solution of dish soap and water may be sufficient.
How to Clean with Dish Soap
- Prepare the solution: Mix a few drops of mild dish soap with warm water.
- Soak the pennies: Soak the pennies in the soapy water for a few minutes.
- Gently scrub: Gently scrub the pennies with a soft cloth or toothbrush.
- Rinse and dry: Rinse the pennies thoroughly with water and dry them with a clean cloth or paper towel.
Dish Soap Advantages
- Gentle: Dish soap is a mild cleaner that is unlikely to damage the pennies.
- Readily available: Dish soap is a common household item.
Things to Avoid When Cleaning Pennies
While cleaning pennies can be a satisfying task, it’s important to avoid certain practices that can damage the coins or decrease their value, particularly if you are dealing with collectible coins.
Harsh Chemicals
Avoid using harsh chemicals such as bleach, ammonia, or strong acids. These chemicals can corrode the metal and damage the coin’s surface.
Abrasive Cleaners
Avoid using abrasive cleaners like scouring powders or steel wool. These can scratch the coin’s surface and diminish its value.
Prolonged Soaking
As mentioned earlier, avoid leaving pennies in cleaning solutions for extended periods. This can cause excessive cleaning and damage to the coin’s surface.
Mechanical Cleaning
Avoid using mechanical cleaning methods such as wire brushes or polishing wheels. These can cause significant damage to the coin’s surface.
Cleaning Collectible Pennies: A Word of Caution
If you are cleaning collectible pennies, it’s important to exercise extreme caution. Cleaning valuable coins can actually decrease their value.
Generally Discouraged
Professional numismatists (coin collectors) generally advise against cleaning collectible coins. Cleaning can remove the original surface patina, which is often valued by collectors.
Seek Professional Advice
If you have a valuable coin that you believe needs cleaning, it’s best to seek advice from a professional numismatist. They can assess the coin’s condition and recommend the best course of action.
After Cleaning: Protecting Your Pennies
Once you have cleaned your pennies, it’s important to protect them from further tarnishing.
Storage
Store the pennies in a dry, cool place, away from direct sunlight and humidity. Coin collectors often use special coin holders or albums to protect their coins.
Handling
Avoid touching the pennies with your bare hands, as the oils from your skin can contribute to tarnishing. Use cotton gloves or handle the pennies by their edges.
The Science Behind Penny Cleaning: A Brief Overview
The effectiveness of these cleaning methods hinges on fundamental chemical reactions. Acids, whether from vinegar, lemon juice, or ketchup, work by reacting with the copper oxide that forms the tarnish.
The acid molecules break down the copper oxide, converting it into a soluble form that can be washed away. Salt enhances this process by providing chloride ions, which further aid in dissolving the copper oxide. Abrasives, like baking soda, mechanically remove surface grime and tarnish. Understanding these basic principles can help you appreciate the science behind this everyday task.
By understanding the science and following the steps outlined above, you can easily restore the shine to your pennies and keep them looking their best. Remember to exercise caution, especially when dealing with potentially valuable coins.
Why is cleaning pennies important?
Cleaning pennies can be important for several reasons. First, a clean penny can be more visually appealing, making it easier to appreciate the details of the coin’s design. Second, cleaning can help remove dirt and grime that obscures the date and other important markings, enabling easier identification and potential historical assessment of the coin.
Furthermore, removing contaminants like oils or fingerprints can prevent further corrosion and preserve the penny’s condition for longer, especially if you’re collecting coins. A clean penny simply looks better, is easier to read, and potentially more protected from further degradation compared to a dirty, tarnished one.
What is the easiest and safest method for cleaning pennies?
The easiest and safest method for cleaning pennies involves using a mixture of vinegar and salt. The mild acidity of the vinegar, combined with the abrasive action of the salt, effectively removes the layer of tarnish (copper oxide) that develops on the surface of pennies. This method avoids harsh chemicals that could potentially damage the coin.
Simply soak the pennies in a solution of vinegar and salt for a few minutes, then rinse them thoroughly with water and dry them with a soft cloth. The light abrasive action ensures the removal of dirt without causing considerable scratches. This process results in a cleaner, brighter penny without significant risk of damaging its surface.
How long should I soak my pennies in the vinegar and salt solution?
The ideal soaking time for pennies in a vinegar and salt solution is typically between 5 to 15 minutes. This timeframe allows the vinegar’s acidity to react with the copper oxide (tarnish) on the coin’s surface, loosening it for removal. Regular observation during this time is recommended.
It’s crucial to periodically check the pennies’ appearance during the soaking process. Avoid prolonged soaking beyond 15 minutes, as excessive exposure to the acidic solution can potentially lead to surface pitting or discoloration, especially on older or more fragile pennies. Rinse and dry the pennies promptly once the desired level of cleanliness is achieved.
What materials do I need to clean pennies using the vinegar and salt method?
The vinegar and salt cleaning method requires only a few readily available household materials. You’ll need white vinegar (a common and inexpensive cleaning agent), ordinary table salt, a small non-reactive container (such as a glass or plastic bowl), and some water for rinsing the pennies after cleaning.
In addition to these basic ingredients, you’ll also need a soft cloth or paper towel for drying the pennies. A pair of tongs or tweezers can be useful for handling the pennies during the soaking and rinsing processes, preventing direct contact with the acidic solution and minimizing the transfer of oils from your fingers to the cleaned coins.
Can I use baking soda instead of salt when cleaning pennies?
While salt is a common abrasive used with vinegar to clean pennies, baking soda can be used as a milder alternative. Baking soda is less abrasive than salt, making it suitable for cleaning pennies that are potentially more delicate or have intricate details you want to preserve. The combination still works to gently lift dirt and tarnish.
The process is similar: create a paste of baking soda and water, apply it to the pennies, and gently rub the surface before rinsing and drying. Baking soda’s gentler action makes it less likely to scratch the coin’s surface. Keep in mind that it might require more scrubbing and repeated applications compared to using salt for pennies with heavy tarnish.
Will cleaning pennies increase their value?
Generally, cleaning pennies will not increase their value and can actually decrease it, especially for collectible coins. Coin collectors typically prefer coins in their original, uncleaned condition, as cleaning can alter the coin’s natural surface and patina. This alteration is often seen as damage and reduces the coin’s authenticity and desirability.
Cleaning should only be considered for heavily tarnished common pennies that are not intended for numismatic (coin collecting) purposes, such as pennies you find on the street or use for practical purposes. If you suspect a penny might be valuable, it’s best to consult with a coin dealer before attempting any cleaning, as professional conservation techniques are often required to preserve a coin’s value.
What should I do after cleaning my pennies to prevent them from tarnishing again?
After cleaning your pennies, several steps can be taken to prevent or delay further tarnishing. Thoroughly drying the coins with a soft, lint-free cloth is crucial to remove any residual moisture that can contribute to corrosion. Avoid touching the cleaned pennies with bare hands, as oils and acids from your skin can accelerate the tarnishing process.
For long-term protection, consider storing the cleaned pennies in airtight coin holders or sleeves made from inert materials, such as Mylar or acid-free paper. These protective measures create a barrier against air and moisture, significantly reducing the rate of oxidation and preserving the coin’s clean appearance for a longer duration. Consistent and careful storage is essential.