How To Clean A Penny Without Damaging It: An Expert Numismatist‘s Guide

As an avid coin collector with over 20 years of experience studying and preserving numismatic treasures, I‘ve seen the good, the bad, and the ugly when it comes to cleaning pennies. There‘s something undeniably thrilling about transforming a dark, grimy penny into a shiny, reddish-golden work of art. But all that glitters is not necessarily valuable in the eyes of a coin grading professional.

In this comprehensive guide, I‘ll share my expertise on how to safely clean common pennies for display or casual collecting, while strongly cautioning against cleaning rare or monetarily-valuable pennies. I‘ll also provide historical context to help explain why certain pennies are worth exponentially more than their face value, and should only be cleaned by preservation experts – if at all.

A Brief History of the Penny

Officially known as a "one-cent piece," the U.S. penny has a storied past dating back over 230 years:

  • The first American penny was struck in 1787 by a private mint.
  • In 1793, the first official U.S. one-cent coins were minted. Designed by Benjamin Franklin, they were made of 100% copper and much larger than today‘s pennies.
  • The familiar "Lincoln cent" was introduced in 1909 to commemorate the 100th anniversary of Abraham Lincoln‘s birth. It was the first U.S. coin to feature a historic figure.
  • During World War II, copper was needed for ammunition, so 1943 pennies were made of zinc-coated steel. Rumored 1943 "copper pennies" are a famous numismatic legend.
  • In 1982, the penny‘s composition changed from 95% copper to 97.5% zinc with a thin copper plating, to reduce minting costs.

Today, there are estimated to be over 300 billion pennies in circulation worldwide. While most are worth exactly 1 cent, some rare variations are coveted by collectors. According to the Professional Coin Grading Service (PCGS), the most valuable penny ever sold was a 1943-D Lincoln Wheat Cent struck in bronze, graded MS63 Red, which sold for $1.7 million in 2010.

Why You Should Never Clean Collectible Pennies

A penny‘s numismatic (collector) value depends on key factors like its rarity, condition, and originality. Improper cleaning can negatively impact all of these qualities, reducing a coin‘s value by up to 50% or more.

Experienced collectors and graders can quickly spot a penny that has been harshly cleaned by observing:

  • Unnatural color and luster
  • Hairline scratches and abrasions
  • Loss of fine details
  • "Stripped" surfaces lacking patina

Even gentle cleaning can alter a coin‘s surface in ways that are difficult or impossible to reverse. An untouched coin with original toning, luster and "skin" is almost always more desirable than a cleaned coin to numismatists.

Statistics from coin grading companies suggest that professionally-graded coins sell for higher prices than ungraded or self-graded coins. In a 2019 auction, two 1793 Liberty Cap cents, both graded by PCGS, sold for $336,000 and $180,000 respectively based on their conditions. Proper preservation makes a huge difference in value.

If you have a potentially rare or valuable penny, resist the urge to clean it yourself. Consult an experienced coin dealer or professional grading service first. Organizations like PCGS, NGC, and ANACS can provide expert opinions on a coin‘s authenticity and condition. In some cases, they may recommend having the coin professionally conserved to stabilize any active corrosion and prevent further damage in a way that does not reduce value.

Safe Methods for Cleaning Non-Collectible Pennies

If you have modern pennies with no numismatic value that you want to shine up for display, jewelry making, or pure enjoyment, there are a few gentle cleaning methods using common household items. However, it‘s important to follow instructions carefully and stop immediately if you notice any damage occurring. When in doubt, err on the side of caution.

Supply List

Here are the basic tools you‘ll need for safely cleaning pennies at home:

  • Soft cotton cloths or microfiber towels
  • Shallow glass or ceramic dish
  • Distilled water
  • Mild, unscented dish soap
  • 100% acetone nail polish remover
  • Non-abrasive plastic or bamboo tongs
  • Small, clean makeup brush or soft toothbrush

Always work in a well-ventilated area, and wear nitrile gloves to protect your hands from any cleaning solutions. Set up your workspace near a sink with running water for rinsing.

Gentle Soap & Water

The safest DIY method for cleaning pennies is a simple soap and water solution:

  1. Add a few drops of mild liquid dish soap to a bowl of distilled water, and stir gently to combine. Tap water can contain minerals that may leave spots.

  2. Drop your pennies into the soapy water, and let them soak for 10-15 minutes.

  3. One at a time, take the pennies out with tongs or your gloved fingers and use a soft cloth or brush to gently scrub the surfaces. Dip them back in the water as needed.

  4. Rinse each penny thoroughly on both sides with distilled water.

  5. Air dry on a clean microfiber towel, or gently pat dry. Rubbing the coins can cause micro-abrasions.

This process will remove most light dirt and oils without changing the zinc and copper. For tougher grime, a second wash with a slightly dampened cloth can be effective. Just be sure not to scrub too aggressively.

Acetone Bath

For pennies with heavier tarnish, an acetone bath can dissolve more stubborn buildup:

  1. Place your pennies in a glass dish and pour in just enough 100% acetone nail polish remover to fully submerge them.

  2. Let the pennies soak for no more than 2-3 minutes, swishing the liquid gently.

  3. Remove the pennies carefully using plastic tongs. Do not use metal tools that may react chemically.

  4. Immediately rinse the coins under distilled water and lay on a soft towel to air dry.

The acetone acts as a solvent to break down contaminants on the surface. However, extended exposure can start to degrade the metal itself, so keep an eye on the clock. Ventilation is extra important with this method.

What About Other DIY Cleaners?

You may have heard about cleaning pennies with acidic ingredients like vinegar, lemon juice, or ketchup. While it‘s true that these kitchen items can quickly remove tarnish thanks to their low pH levels, they are not recommended for cleaning coins. The same goes for other abrasive substances like salt, baking soda, or toothpaste.

According to the American Numismatic Association, any substance with a pH below 7 can corrode a coin‘s surface and permanently alter its appearance over time. Exposure to acidic cleaners can give pennies an unnaturally bright and shiny look, almost like they have been stripped. Conversely, using overly basic cleaners like ammonia or bleach can discolor coins and pit the surfaces.

If soap or acetone yield unsatisfactory results, it‘s better to seek professional cleaning help rather than reaching for harsher household chemicals.

Cleaning Large Batches of Pennies

To clean a big batch of circulated pennies for a craft project or just for fun, you can scale up the soap/water or acetone methods in a large glass container:

  1. Make sure you can fit all the pennies in a single layer without overlapping. This ensures even exposure to the cleaning solution.

  2. Follow the same basic steps for washing or soaking, working in batches if needed.

  3. Use a mesh strainer lined with a towel to air dry the pennies. This prevents water spots.

  4. Lay the coins flat to finish drying completely before storing them. Trapped moisture can lead to corrosion and odors.

It‘s normal for some pennies to come out shinier than others based on their age and composition. Don‘t keep soaking them in an effort to get them all perfectly matched. The goal is to remove surface contaminants, not to strip away all of their character.

Long-Term Penny Storage Tips

After cleaning your non-collectible pennies, proper storage is key to keeping them looking their best. Always store coins in a cool, dry place with stable humidity levels. Avoid areas prone to temperature swings, like attics or basements.

Use archival-quality plastic flips, coin tubes, or albums to protect your pennies from dirt, moisture, and contact with other metals. Look for holders made of inert, non-PVC plastics that won‘t leach chemicals over time. Coin collecting supply companies sell storage solutions in every size for both individual coins and large collections.

The Bottom Line on Cleaning Pennies

As a seasoned numismatist, my golden rule is this: if you think a penny might be valuable, don‘t clean it yourself. The risk of permanently lowering its collector value is just too high. Find a reputable coin dealer or grading service, and let the professionals assess it first.

For newer pennies that you want to brighten up for artistic purposes or casual collecting, gentle cleaning with soap/water or acetone can yield satisfying results when done carefully. Steer clear of acidic or abrasive cleaners, and always use the mildest method that gets the job done. Proper storage will help preserve your handiwork.

Remember, a penny doesn‘t have to be shiny to be special. Sometimes, the history told by its toning and wear is what makes it a priceless treasure in the eyes of a passionate collector. By taking great care with the pennies in your possession, you are preserving a small piece of the past for future generations to learn from and enjoy.

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