It goes in paint and all, just best to clean off any oil and grease that's present. Doesn't really take that much longer with paint, it just depends on the thickness of the paint. If it's thin it'll take no time at all with enough current to strip it off.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.