I've read a load of threads on spraying bumpstrips from plastic. I was just wondering whether you should do anything different if they've already been painted? I've bought some ones in silver (thanks to greenmini) which haven't been sprayed very well. They weren't sanded down properly as the texture is still showing through, and the paint's flaking off.
Should I sand it down straight away, or strip the paint off first? And would it be better to start off with a coarser wet and dry because of the paint and primer already on there?
Thanks in advance.
(Just to add: they weren't sprayed by greenmini! don't want to give him a bad reputation)