Any form of coin cleaning will, at minimum, strip a tiny bit of the lining off. But some methods are more damaging than others. A few are mild enough to count as non-damaging. There are multiple ways you can clean old copper coins without damaging them.
There are many methods to clean coins, even as experts argue over whether coins should be cleaned at all. If you really wish to clean coins, make sure you start with coins of no numismatic value. Also, keep in mind that modern-day change has a different metal composition than older coins.
In this article, we’ll be looking into some of the most popular coin cleaning methods and a few that you should avoid. Just because a method is mentioned here doesn’t mean that it is recommended, so read carefully.
History of Coin Cleaning
There’s no way of knowing how long coins have been cleaned, but we have a better idea of when the process became controversial. Cleaning coins was actually routine by collectors for a long time. After all, a shiny coin looks more attractive than a tarnished one, doesn’t it?
Cleaning coins was a popular and common practice in the United States from at least the mid-19th century. In the 1930s, a common belief was that ‘brilliant is best.’ As a result, collectors cleaned coins to remove tarnish, sometimes ruining them in the process. Even when it worked, the tarnish returned quickly, necessitating retreatment.
In the mid-1980s grading became a way of rating coins. Grading looks to minor details like scratches, nicks, and the wear of fine details, but not tarnish or dirt. Since most ways of cleaning will, or at least can, diminish the grade of the coin, cleaning became undesirable to most collectors, especially as looking under a microscope revealed the extent of ‘invisible’ damage cleaning can do.
Should You Clean Your Old Copper Coins?
No, you probably shouldn’t. It devalues the coin and can completely ruin it if done wrong. There may be times you want to clean a coin anyway. First, ask yourself why you want to clean this coin. Is it so it will look better? It might. So it will be more valuable? It won’t.
If your coin has numismatic value, such as being very old or rare, don’t clean it.Any cleaning that is possible to do without damaging the value is far beyond what an amateur can do at home. But, maybe you have a coin that is of no collectible value but is of value to you, such as sentimental value. Or maybe you wish to make jewelry or some other form of art and want the coin shiny.
A few things to keep in mind. Tarnish will return quicker than it took to accumulate in the first place. Coin metal compositions change. In the U. S., cent pieces (pennies, colloquially) moved from being mostly all copper, to almost entirely zinc with a copper cladding in 1982. This will affect how well some cleaning methods work. Since this article is on old coins, we are talking pre-1982.
How To Clean Old Copper Coins Without Damaging Them
There is a reason that proof coins are often encapsulated in plastic. That’s because every time the coin has exposure to something, it loses a little bit of the metal. Exposure to various elements such as air, water, or the oils in your hand can corrode the metal. Everything that is used to clean a coin will remove a little metal too.
Any cleaning method will cause a little damage to your coin. Sometimes that damage is microscopic. Sometimes it is obvious. While there is no safe method, there are a few that are more common than others. Here are some of the most common.
How To Clean Copper Coins With Baking Soda
This method will clean your coins, leaving them shiny again. It is also abrasive, and even if you are super careful, there will be microscopic damage. So do not do this on any coin of value. That said, it can be a fun science experiment for children.
Take small amounts of warm water and baking soda until you have a paste. Pick up the coin you want to clean and gently rub the paste over the front and back of the coin in small circular movements. Rinse under warm water and let air dry on a soft towel. Do not rub with the towel, that will cause micro scratches.
This method is damaging but if done right none of the damage will be visible to the naked eye. So if your coin has no numismatic value, this method is safe enough.
How To Clean Copper Coins With Vinegar
Like the previous method, this is very good at leaving your coins shiny. Also, like the previous method, this is abrasive and will cause tiny, hopefully invisible, bits of damage. So, once again, do not do this on a coin with numismatic value. That said, if your coin isn’t valuable, this is a good way to make it look new again. There are actually several ways to use vinegar to clean coins.
Method One: Take about a quarter cup of white vinegar and dissolve about a teaspoon of salt in it by stirring. Place your coins so they aren’t touching or on top of each other. Leave them to sit until they reach your desired level of shine. Check at five-minute intervals, it shouldn’t take more than 15 minutes. Rinse with warm water and pat dry with a soft cloth.
Method Two: Make a paste of salt and white vinegar. Apply the paste thoroughly over the coin, which should show a difference immediately. Rinse and wipe clean. Some use baking soda instead of salt which will have a similar effect and be very foamy.
Variations Of The Vinegar Method
Because the vinegar method requires an abrasion ingredient (salt) and an acid (vinegar), this method, especially the paste, can be used with substitutes.Ketchup is a common one, as it actually contains both salt and vinegar in one. Tabasco sauce can work as well. Lemon juice can substitute for vinegar.
How To Dissolve A Penny In Vinegar
This is not how to clean a penny but can give you an idea of how dangerous this method can be.Dissolve as much salt as possible in a quantity of white vinegar. You’ve now made hydrochloric acid. Drop a post-1982 penny for quicker results, as zinc dissolves faster than copper.
When the penny is clean, remove it with tweezers or a spoon. Do not touch the coin! Do not rinse but place the coin on a towel to dry. The penny will react to air, forming copper oxide, turning it green. Drop it back into the acid and repeat. Every time you do, you are stripping a little copper off the lining. Eventually, the zinc will be exposed. Leave it until the penny dissolves completely.
How To Use Vinegar To Rip A Penny
Related to the last, it is possible to dissolve the zinc core of a post-1982 penny while leaving the copper cladding mostly intact. Use sandpaper at the top and bottom of the coin to grind through the copper, revealing the zinc. It doesn’t have to be a large amount. Drop the coin in the acid. It should bubble immediately.
When the zinc core is eaten away, the penny will float. Use a spoon to scoop up the coin and drop it in a baking soda and water mixture to neutralize the acid, then a cup of water to rinse. You can then drop the coin in acetone briefly so it will dry quickly before placing it on a towel. Do not touch the coin until it is dry, use a spoon for each step.
You now have a paper-thin wrapper of a coin. Handle it carefully until you are ready to rip it because there is pretty much nothing there. But now you have an easily breakable penny for a magic trick or bar bet. Fair note, this and the last trick do technically count as destroying money which is actually illegal.
How To Clean Copper Coins With Coke
Some people swear by this method. Brand name isn’t important, just a cola soda. Fill a glass with a quantity of cola deep enough to cover the coins. Place the coins so they are not touching or on top of each other. After two hours, flip the coins over. After another two hours, remove the coins and rinse them. Let them dry.
Like the vinegar, this is an acid. Using this will strip away the dirt, grime, and maybe corrosion, but it will also strip away some of the copper which can affect the grading. Do not use this method on a coin of numismatic value.
Other Ways To Clean Copper Coins Without Damaging Them
1. Use Water
Sometimes the simplest methods are best. Warm distilled water can be used to clean coins. Use distilled water because chemicals in tap water may cause discoloration. If necessary, a little bit of gentle soap can be used, with Ivory soap being the preferred brand. Some mention using an old, soft toothbrush to lightly scrub, but you risk abrasions that way. Pat dry with a soft towel, do not rub.
2. Use Olive Oil
A slightly more controversial method with some swearing by it, while others claimed to be left with greasy coins. If your coin has no numismatic value and is very dirty, it could be worth a try. Though this method certainly takes the longest time to complete.
Like the others, you need a container where your coins can sit without touching or overlapping. Then pour over them enough olive oil to cover them. Cover the container and set it somewhere out of the way. How long to leave it seems to vary with suggestions ranging from several hours, to days, to check on it in a month, though it could take up to six months.
If the oil starts getting cloudy, discard it and add new if needed. Once you suspect the coins have soaked enough, try washing them with warm water and mild soap. A soft toothbrush may be needed to scrub. If the dirt doesn’t come off, put them back to soak. Discard the oil when finished.
Should You Use An Ultrasonic Cleaner
An ultrasonic cleaner uses water, preferably distilled, detergent, and sound waves to clean the dirt off of small items, such as coins. Some collectors appreciate using these, while others disapprove of them, believing the vibrations damage coins. Even the ones who do use an ultrasonic cleaner say they work better on silver coins as bronze and copper require a stronger detergent.
These are not the cheapest of equipment, so you probably do not want to buy one just to use on copper coins. You also have to clean the coins with water and soap or olive oil before using the ultrasonic cleaner, anyway.
How To Absolutely Not Clean Coins
While no method is foolproof or completely harmless, some methods are more damaging than others. One method that was used in the past was known as whizzing. This involved scrubbing the coin with a fast-moving rotary brush. Do not do this.
Do not use jewelry polish on any coin, not even the silver ones. This will decrease the value. Do not use coin dips that can be purchased at hobby shops. These are acids and are likely to affect the grading of your coin, and any corrosion removed is likely to return at a comparatively rapid rate.
How To Know If A Coin Has Been Cleaned
If a coin’s age doesn’t seem to match its condition, such as an old coin that seems very clean, there’s a decent chance the coin has been cleaned. Probably dipped in acid. Look to the lines on the coin. If they seem softer than they should, or if little scratches are evident, then the coin may have been cleaned improperly.
This is likely to remove corrosion but is a temporary measure at best. Expect the corrosion to return, possibly as quickly as a few months. Be cautious about buying such a coin.
Final Thoughts
There are a few ways you can clean old copper coins. It is better not to clean coins, even if you can’t see any damage, it will decrease the value of the coin. If your coin is not one you plan to sell, then cleaning is possible, but you must be careful.