I’ve really struggled coming up with a good way to clean copper coins like large cents and Indian head pennies. Most of the time you’re not going to hurt the value as it has already lost all or most of its value from corrosion so I am more interested in cleaning them up to actually see the detail and get a date from it.
Here is a quick example of how corrosion hurts the value – Years ago I found a stunning 1872 Indian head penny with beautiful detail. It looked like it was dropped the day it was minted besides the green patina that you’re going to find 99% of the time on a dug copper coin.
Curious if there was any value to it with the green patina, I went to three different coin dealers over the course of several weeks to find out. Each one gave me a value somewhere around ten dollars. Not bad for a coin with the face value of one cent, right? Well, if the coin didn’t have that beautiful green patina it would have been worth several hundred dollars!
After finding out how the beautiful green patina effects a coins value I was no longer worried about cleaning copper coins at least to where they are presentable. Often, I find myself cleaning copper coins and copper and brass buttons just so I can see the detail and get dates to show.
In the past I have tried several different methods at cleaning copper coins with little to no success. At one time, for really corroded copper coins that I couldn’t even make out detail I would use a product called MS 70. It would literally strip the coin down the bright, shiny copper. Once the coin was stripped then I would use another product called Dellers Darkener that you would rub on the coin until you got the desired darkness you wanted. I will say it worked amazing on the worst of the worse but was entirely to harsh for cleaning dirty copper coins even if they had some corrosion. I know this sounds harsh but one time I found a large cent that I couldn’t get a date to show. A friend suggested tumbling it and even that didn’t make it readable. A few years later, after finding out about MS 70 I decided to try it and follow up with Dellers. Not only could I clearly see the date, you could clearly make out the details! Unfortunately, you can no longer get Dellers Darkener and the formula for MS 70 has changed and will no longer strip a copper coin.
Another method I tried and stuck with was simply picking at the copper coins I was cleaning with a toothpick, once as clean as I could get it, I would simply rub some wax on it. Depending on the condition of the coin this worked with mixed results, but it’s been my method for the last several years
Composite Cleaning Pencil
I recently got a composite cleaning pencil from my good friend Brian Harvey from Diggers Den. A few months back I had Graham Dempsey on the All Metal Mode UK podcast who makes the pencils. He is a fellow detectorist who has been in composite engineering for almost 30 years. I had to try it!
The composite cleaning pencil comes with two filaments. One is used for removing heavy material and the other is for removing the finer material once you’ve removed the big stuff.
The first coin I used it on was the large cent. Although it wasn’t easy to do, I ended up overcleaning it. I actually removed so much patina that there were bare copper spots. How it happened is you can clearly see the bubbles on the large cent, the coin was so crusty I just thought it was dirt but instead it was where part of the coin bubbled up. The coin is pretty well trashed, but it did clean it as good as you could expect a trashed coin to be cleaned.
With more practice and learning to take it slow I’ve had excellent results. The filaments hold up really well and will probably last me a lifetime. I have heard that some of the other composite cleaning pencils are known for being messy and the fiberglass splintering and coming apart. Graham Dempsey assured me this would not happen with his and after many coin and buttons cleaned by me, I believe him!
If you’re like me and have a bunch of crusty, nasty copper and brass sitting around that needs cleaned up I say look no further! This is the best thing I’ve ever found for cleaning up even the crustiest of coins and the best part it’s chemical free. Not to mention very affordable!
I too had some issues with cleaning my coins. A friend told me to place them in a solution of salt and water. Let the coins soak for a day or so. After a day I’d use a soft brush with dawn soap and be able to see detail without marking the coin.