my friend is selling his extra GT bumper, and its primed, ready to paint, however there are some hair line scratches on it, no cracks or breaks, but will the scratches disappear after its painted and clearcoated? will they disappear if sanding is added to the process?

 

just a opinion-
if theyre just minor scratches, they could be spot putty filled, but ifthey are actually stress cracks, Id think theyd need taken down into the plastic and filled/blocked out. the bumpers are a lot harder than the old urethane ones, when I tore mine up it had a couple cracks in the paint that looked like scratches till the paint started chipping away at the edges- was kinda hard to see they werent scratches- but bowing the bumper a bit by pushing on it you could feel the paint lift enough to catch a thumbnail on...paint flexed/cracked, was lifting from the plastic...watch for too many coats of paint- too thick over plastic could cause issues- why is it primer? was it repaired already? PPG/others sell a flex additive for plastic bumpers, might see if its recommended, and ask what primer they used on it...

 

wow! thanks thats alot of good information! okay well its not painted thats what i meant by primer, its plain black in color, and this scratch in the picture was the one bugging me. good thing it doesnt have paint on it right now otherwise id do what you said about the bowing and checking painted layers, he said if i sanded it it should be okay, what do you think?