Coin Cleaning... To Clean or Not to Clean your Metal Detecting Finds?
by J.R. Hoff
There are two rules to cleaning coins:
First, check the date and mint mark on the coins you want to clean. Be absolutely positive that they are not key collector coins but common coins that are worth face value or silver (or gold) value. There are two categories that we need to discuss and they are copper coins and silver coins. Nickel coins can be cleaned the same way as copper. I will link you to some of the coins on HDWT that have been cleaned using the various methods. Some are worthwhile and some are, well, I'll let you be the judge. Remember, cleaning a coin de-values it considerably. I clean my coins to make them more presentable and with the foresight of knowing that I am not going to sell them.
Clad coins are the easiest to clean and if you goof up and they look bad, so what. They are still spendable. I tumble all of my clad coins with pretty good results. It is an effortless job. I fill the tumbler between half and 3/4's full of coins, add water about a 1/2" above the coins, slice in some Ivory soap and let the tumbler do it's job. Always tumble like coins such as quarters, dimes and nickels. If you put copper pennies in with the clads they are going to turn a copper color. Clean your memorial pennies the same way but by themselves. This method will clean all of the dirt off of them. It will not remove stains though. To remove stains from coins, soak them in one cup of white vinegar with a tablespoon of table salt. Let them sit as long as needed, even overnight. Changing the solution in between soaks can help a lot with stubborn stains. After soaking them, put them back in the tumbler and then they should be ready to spend.
I have heard of people putting the clads in a tumbler (after using the methods above) with sawdust or wood shavings. I personally have not tried this but I think it would work great at "polishing" them. This is all I do on clad coins. Anything more in my opinion is too time consuming, especially for clad coins.
Okay, you got me on this one. I tumble wheat pennies. I always check the date and mint mark and if it is a common wheat, it goes in the tumbler. The way I look at it is, out of the ground it is worth a penny, cleaned up it is still worth a penny, only now it looks better. I also clean wheat pennies with a brass brush. The same type of brush used for cleaning suede shoes or your BBQ grill. That's right! Brass is softer than copper. Sure, you can put scratches on a penny if you scrub it too hard. Be gentle, use a circular motion, back and forth and sideways. Whatever it takes to clean it up. Check out these examples of cleaned wheat pennies using a brass brush: Example One, Two, and Three. In example three you can see that it doesn't always work. These wheat pennies are so encrusted that they will never be cleaned to the point that they have eye appeal. You lose some, you win some.
Other methods I have tried on wheat pennies (but no longer recommend) are soaking them in the vinegar solution. Oh yes, it works great. They come out a dull copper color, similar to a new penny only dull looking. Years ago after doing this I rubbed sulfur on the surface of the dull coin and they toned up nice. It actually worked very well. Environmental reasons prevent me from using this method plus health and safety would also be a concern. Better that you learn what not to do from HDWT than experimenting on your own. Learn from my mistakes, that is the purpose of this article. Also, don't soak them in bleach. It doesn't work at all. Don't use Ajax cleanser (or similar products) on copper coins. I did back in 1975 and almost ruined my most favorite coin...the 1796 Liberty Cap large cent. Twenty five years of natural toning has helped it look pretty good now. When I first cleaned it, shiny copper areas could be seen everywhere. I sent it in to a grading service and it came back as a Good 6 with environmental damage. However, they did not slab it.
Don't Use AJAX Cleanser on Coins!
Also, if you use electrolysis to clean copper coins they come out the same way as using the vinegar method. Soaking them in vinegar or using electrolysis also lifts dirt out of holes on the coins that you didn't know were there. Don't use it on coins that you want to give eye appeal to. I have tried the "olive oil" method of soaking copper coins. It takes too long and doesn't work very well (my opinion).
There are several ways to make silver coins look very presentable. Occasionally you can dig a silver coin out of the ground that looks great. Ok, more than on occasion because silver actually fares very well in the soil compared to copper. I use a soft toothbrush with warm water and soap. That is usually all they need. The examples above also have silver coins included in the picture. They were all cleaned with just a toothbrush. This is the best example.
Sometimes silver does get stained or so encrusted that you have to use other methods. You can use electrolysis or the vinegar solution. They will also turn a dull silver color. Now you have another problem that has to be addressed... the dull color on a nice silver coin. Well, I use a product called Wrights Silver Cream. It will take the dull away, I guarantee it! It can be purchased at your local grocery store or jewelry shop. I have also used it on silver coins without soaking them in vinegar and they still come out very presentable. There is one problem with using the silver cream. They will be shiny looking when you are finished with them. An example can be found here. See how shiny it is. It actually caused the light on the scanner to reflect causing a bad scan. It actually looks better visually looking at it. The 1874 dime that I recovered last June had to be cleaned with the silver cream. It had a bad black stain on it but now it looks pretty good. Sure, it hurt the value somewhat, but it is not for sale and I don't have to look at that black stain anymore. You have to decide for yourself whether or not to clean an old silver coin. The 1878 dime was cleaned up with just a toothbrush and it looks just fine.
That is about it for cleaning silver coins. Anything more than what is described above and I think you would run the risk of ruining your coin. The bottom line on silver is, try cleaning it with a toothbrush in warm soapy water. Next try the silver cream and as a last resort, soak it in the vinegar solution.
Silver rings can be cleaned up nice on a buffing wheel with Wrights Silver Cream. I have gotten incredible results using this method on silver rings. One last note on the silver cream. That black stuff you see when cleaning the coin or ring...that is silver being taken off of the surface! You be the judge.
How Not to Clean Coins
Do not use muratic acid to clean your coins. It is a mild solution of hydrochloric acid (HCL). Yes, I have used it on coins and ruined a good Flying Eagle cent and two shield nickels. It only takes seconds to reduce the coin to nothing more than a slug. I also tried it on an aluminum token. It dissolved it completely. The same goes for sulfuric and nitric acid. Unless you are trying to make slugs, avoid using them. Acid is very dangerous and should be used outdoors with plenty of ventilation. Don't use gasoline, bleach, Clorox, ammonia or any combination of common household cleaners. They won't clean coins as good as what I have described above. Learn from my mistakes. I worked in a laboratory back in the 70's and tried the various acid's using a hood to vent the vapors. The results were awful to put it mildly. DON'T USE ACID TO CLEAN YOUR COINS!!! It is not worth it.
One last note. Refer back to rule number one!
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