Acetone: What does it work best on?

[VAB2013]

I picked up a can of "Goof-Off" (100% Xylene) at Walmart for about $3.50 and gave it a trial. It helped a little, but I'm not convinced that it helps that much, yet. Does anybody have any ideas on proper usage of Xylene to dip copper Lincolns and silver Roosevelts?

Guys there are two posts above this one that need answers.
So that is what Xylene is! I am familiar with Goof Off and it does stink. My Maint Tech used it to remove paint from cabinet doors and he almost passed out. I got woozy just walking in the kitchen to check on things and had to get him to walk outside!