How To Clean Copper Coins Found In The Ground

Whether you’re a metal-detecting hobbyist or just curious about a coin you found buried during a walk in the woods, it’s easy to find yourself intrigued about what lies underneath the layers of mud, dirt, and oxidation. It’s therefore useful to know how to clean copper coins found in the ground.

You can clean copper coins found in the ground using a variety of methods, the safest being with distilled water, and the aid of a soft toothbrush. However, as a general rule you should avoid cleaning coins if you’re collecting them, as it can actually diminish their value.

However, there are many different opinions on how you should clean copper coins. After all, cleaning a coin could cause irreversible damage, impacting its numismatic or even historical value. Read on to discover some safe cleaning methods to use, along with some riskier but satisfying ones too!

It Is Not Recommended To Clean Coins

We’re going to begin this article by clearly establishing a very important bit of information when it comes to coins: They should never be cleaned!

Although the appeal of a shiny copper coin is enough to make anyone curious, the irreversible act of cleaning a coin could potentially erase its worth, jeopardize the history it holds, and scupper your chances of selling it on.

Believe it or not, in many cases collectors and historians see more value and appeal in an old coin with its natural patina coating over one which has been cleaned. As long as a date and other inscriptions are still legibly visible, the coin may still be identified and valued.

It may sound backwards, but it’s true! Pursuing that shine may cause the coin to lose its appeal, thus rendering it less valuable numismatically.

Before You Begin Cleaning Copper Coins

If you understand the risks but are still adamantly sure you’d like to pursue a coin-cleaning endeavor, it is very important to plan ahead and prepare correctly. Before we share some methods to use to clean your copper coins, here are some handy tips to help get you started.

Have A Trial Run

It’s the age-old rule: Practice makes perfect! You might want to experiment with coin-cleaning on some of your not-so-valuable coppers, ideally ones still in circulation.

You’re bound to have a few pennies loose in your wallet, some of which will more than likely be rather dirty. Practice some of the below methods on those and see how you get on before attempting to clean any more-valuable coins.

Be Sure Of The Metal

As you will have inferred from the title, this guide is designed to help you clean coins made out of copper. It may sound obvious to check which metal you’re dealing with, but the wrong guess could lead to irreversible damage on a coin.

Coins minted from silver, nickel, or even gold will all react differently to various cleaning methods, due to their chemical compositions. So, if the coin in front of you isn’t copper – this guide won’t be very useful!

On top of this, it’s also vital that you ensure you’re not mixing coins while you clean them. Not only do different coins require different treatments, but mixing various metals together during cleaning could cause further undesirable reactions, leaving your coins at risk of being worse off than they were before you began.


If you are unsure or don’t feel confident cleaning your coin, then don’t try it! As discussed above, the risks of damaging a precious coin far outweigh the benefits of a bit of sparkle.

But, if you’re still on the fence, take the coin to a dealer. By examining the coin in person, an experienced coin expert will be able to make recommendations specific to the coin, and help you make a decision on how to clean – or tell you why you shouldn’t clean – your find.

The Effect Of Oxidation

With copper coins in particular, oxidation is usually the factor which spurs finders into wanting to clean them up. That naturally occurring green rust is definitely less aesthetically pleasing than a mint condition shine. But what is it, and how can it be removed?

What Is Oxidation On Copper?

Oxidation naturally occurs on copper as a result of the metal’s exposure to various elements. Both air and saltwater lead to oxidation on copper, so it’s inevitable oxidation will occur on coins lost in the ground over time!

As a result, a blue-green colored coating forms on the copper. Although this may not appear as aesthetically pleasing as the red-brown shine of a newly minted copper coin, this outer layer actually forms a sort of barrier around the coin, protecting it from further exposure to harmful elements.

This natural combat is one of the many qualities which deems copper a brilliant choice for coins. A good way to demonstrate this is by comparing the effects of oxidation on copper and on iron.


As you will know, the rust which forms on iron doesn’t securely coat the metal. It can instead be wiped away with ease, leaving the metal vulnerable once more to the elements, thus risking further damage and corrosion.

Copper, meanwhile, naturally defends itself, making it a durable, long-lasting metal which proved itself a good option for coin minting. The use of copper for money dates all the way back to the 3rd century BC, and the Royal Mint struck its first penny in the 1700s!

How To Remove Oxidation From Copper Coins

Although the oxidation barrier occurs as a protectant over the copper, there are various methods you can use to try to remove it. If you have decided cleaning your copper coin – of oxidation, soil, or anything else it came into contact with when it was in the ground – read on to determine some safe, effective methods you can try.

How To Clean Valuable Copper Coins Safely

Below we have highlighted some safe methods you can use to clean your coppers. Especially if you suspect the coins might hold some value, these options are a good place to start to remove any residue coating from the ground.

Safe Method

Probably the safest – and easiest – method of cleaning copper coins is to simply use water. Especially with coins caked in thick soil which are unidentifiable without a bit of a wash, this method will help remove the superficial dirt, without impacting the patina.

All you need to do is soak your coins in a bowl of hot water overnight. That’s it! Then, you should be able to identify your coin, determine its value, and help you decide whether or not to keep cleaning.

But remember that salt water induces oxidation on copper! Similarly, water from a faucet may be chemically treated, which could damage the coin further. Therefore, distilled water is undeniably the best option.

Household Helpers

To add a bit of strength to the above method of soaking your coins, you could always use the aid of some simple household supplies to help clean those coppers. First of all, try adding a small dash of liquid hand soap to the bath of distilled water. This will gently help wash away more of the dirt, which can be patted away with a soft cloth.

Another idea is to mix a small amount of baking soda with water and rub it gently over the coin with your fingers.

Dry Method

Copper coins found in the ground may also be cleaned whilst dry. Using a toothpick to gently scrape away the dirt will help reveal a coin’s inscription, and therefore its value can be better assessed. Similarly, a soft toothbrush could also be used to gently brush away layers of soil.

Specialty Products

A quick search online will pull up hundreds of specialty products advertising their use as effective copper or coin cleaners. Many of these claims will be valid, and these products are reliable options for cleaning. However, some may have adverse effects you need to be wary of.

There are items such as glues, soaps, special pens and solvents which many enthusiasts rely on for their cleaning needs. We won’t name any specific brand here, but make sure you read product reviews and test out the cleaner on pennies before you commit to cleaning your valuable coins.

Your best bet is to ensure you’re choosing products created specifically for coins, and strictly always choose products directly designed for copper. Silver jewelry cleaner won’t be your friend here!

Cleaning Non-Valuable Copper Coins

Now, for all we have stressed about how you shouldn’t clean your coins as it jeopardizes their numismatic value, we must also mention that coin cleaning can be a fun hobby in itself. Particularly with pennies and coins still in circulation – which won’t be attracting large demand from collectors any time soon – cleaning can be a rather satisfying process.

If you’re cleaning old, non-valuable pennies for a hobby, that’s where you can get very creative. Coca-Cola and Tomato Ketchup are popular products to use to clean pennies, which is a use you may not know these liquids have!

Other Equipment

Also, there is also a lot of high-tech equipment which can be used for coin cleaning. Ultrasonic cleaners can be intriguing and exciting to use, but perhaps the most satisfying method is to use a tumbler.

Used primarily for rocks, a tumbler is effectively a large drum which spins its contents hard and fast, in order to polish up what’s inside. Although this method is highly likely to cause scratches, dents, or even breakages, using the right tumbler and cleaning medium inside is guaranteed to bring out some shine. 

Of course, shiny pennies may then be used for all sorts of things, not just spending, but also for crafts, DIY projects, or even just to squash in the penny press machines you find at tourist attractions!

Final Thoughts

To clean copper coins found in the ground, the safest method by far is to use distilled water and a soft bristled toothbrush. You should avoid cleaning any coin if you’re collecting it, as doing so can damage it and therefore reduce its value.

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