Ok, I've heard the sermon many times: Don't clean your coins. Well, I was metal detecting in the yard behind my new house. Okay, the house isn't really new, it's 150 years old. I dug up a few coins which are encrusted in what appears to be a crystalline substance (maybe from the metal being in contact with minerals in the soil.) I can't quite Identify them, and they won't come clean with water. Any suggestions on how to clean them without destroying them? It seems to me most are silver coins, but I'm not quite sure yet. If they're too far gone, I'd be happy just to have bullion value coins for free. Thanks in advance, Josh
The down fall to cleaning your coins will be that any numismatic value that they may still have will be diminished greatly. However if they are covered with something that is corroding them then their numismatic value is in trouble already. Bottom line is they are yours to do with what you want. If I were you, I'd take my time, do some research and then do some trials. I've used olive oil to disolve gunk off old coins before with great success, but it took months. Good luck and congrats on the find.
If they are silver, olive is not too effective with it. If it is possible, can you post a picture of what you got there? If the silver have been exposed to some strong sulfuric enviroment since soil can contain a fair amount of them, it can be possible that the silver coins you got there are quite badly damaged. Congradulations of your findings though.
If the coin is "too far gone" to even be identified as a silver coin, I'd just go ahead and clean them. I don't think you will reduce the value at this point.
Generally, any silver conis that I dig I put immediately into a vial of water, then rinse them gently when I get home. They will never look perfect, because the dirt will scrath the delicate silver, but they can look okay. That was how I got a nice AU 1924 Standing Liberty quarter, from under four inches of dirt. No matter how careful you are an expert can tell. Still, even cleaned you still have the bullion. Good luck detecting.
I would say let them soak a bit in distilled water, not oil. If need be heat some water, put some mild dish washing and do light scrubbing...this has helped with me...if you have chunks you can use a dental pick to pry them off but be carefull...
Start with distilled water and gently, very gently splash around the water with an artist paint brush. If nothing happens, try adding a little baking soda to the water. It is true that if your coins are Siilver and the ground is acidic or caustic, the coins could now be covered with compounds of that substance. Silver is highly reactive and will combine with many substances such as Sulfides, Sulfates, Fulminates, Chlorides, Iodides, Oxygen, etc. The reason is it's outer shell of electrons has only 1 making it suseptical for combining with just about anything in the soil. Back to the method of cleaning. If a very fine paint brush with the baking solution has no effect, try the old faithfull Acetone. Again, just lightly brush with an artist type brush. If all these methods fail then it is just experiment time. Try anything you have laying around the house such as Lemon Juice. Always do it gently though. And remember that any contaminate you remove from the coin was probably there due to the Silver combining with some other agent and removing the contaminate means you will be removing some Silver. You can not pull a Sulfate from the coin leaving only the Silver behind.
