I am ready to start some body work and I want to do the bumpers.
I can not remember what I used to clean them real good, prior to paint them, I painted them about 12 years ago with some black paint, 3M makes some kind of putty for cracks, Monday I'll go to autozone to see what they have.
Is the paint off? I'd just use acetone, thinner, or something that did not leave a residue. I lightly primed the "black" part and then painted it. There is an additive that makes the paint somewhat flexible so it will not crack as easily.