Graffiti Removal

I'm working on removing the graffiti from the rock on my hiking trail. First I tried a wire brush, which took the paint down from a bright green to a gray-green, but it was still clearly visible. The right part of the tag in this picture has been brushed, and the left part is as it was originally.



Next I tried Goof Off with a wire brush.



I don't know . . . does this look any better? Now it's a blurred tag, but still clearly there.

I see that Goof Off makes a special graffiti remover, which I haven't seen in the stores. I may have to order some and try that next.