When I dig a coin, first I determine how rare/valuable it is before doing anything. If it is of moderate to low value, I do the following:
Remove as much loose soil you can and analyze the extent of the dirt.
In a glass container, fill with enough hydrogen peroxide to fully immerse a coin. Place coin in peroxide and swirl to remove loose soil. Remove coin and place on paper towel or soft cloth. Dip Q-tip in peroxide and lightly brush surfaces to remove as much loose soil as possible.
Often this is enough to clean the coin to satisfaction. Note, many people prefer the "boiling peroxide" method. I find that it severely dries out your coin and I have had more success using these other methods described.
If not, I then assess the condition to determine what course of action to take: For stuck on crust, I use a rose thorn to remove it. Be sure to have a peroxide solution and Q-tip handy to dab the spot you are picking at with the thorn.
If the coin is really bad and dried out to the point where details are hard to see, I then place the coin in a container with enough olive oil to immerse the coin. I let it soak in the oil for a few days and then take it out to assess the condition change. Sometimes it improves the appearance quickly, sometimes it takes weeks!
I only "ruined" a dug coin one time and that is because I used lemon juice in an attempt to remove excessive green that was hiding the details. I went too far and removed too much green and "cooked" the coin. If I had just used olive oil, I am sure the coin would have turned out far nicer than it looks now. It was a valuable coin too...
Edited by jerseyben
06/17/2014 2:21 pm