I left it to soak overnight in acetone, then by the next afternoon most of the gunk is gone. No more gunk in big open areas. I gently used a toothpick and cotton buds to get the rest off.
Here's the before pics. You've seen them before in this forum:


This is after an hour's work picking gunk from tight spots. I didn't manage to finish on that day, so I continued the next day and the coin got another night in acetone.


I'm certain the very green bits are PVC and the greyer ones gunk. No matter what I did I can't get the green from the pits in the obverse out. The green on the V is also extremely stubborn. I didn't clean much between the denticles because I'm afraid I might scratch the patina off.
So in conclusion: cleaning the gunk off a coin won't help it's grade. But it does have more eye appeal since it's so clean
Here's the before pics. You've seen them before in this forum:


This is after an hour's work picking gunk from tight spots. I didn't manage to finish on that day, so I continued the next day and the coin got another night in acetone.


I'm certain the very green bits are PVC and the greyer ones gunk. No matter what I did I can't get the green from the pits in the obverse out. The green on the V is also extremely stubborn. I didn't clean much between the denticles because I'm afraid I might scratch the patina off.
So in conclusion: cleaning the gunk off a coin won't help it's grade. But it does have more eye appeal since it's so clean


























