The Upol primers I used were their self etching for metal which I used on the metal chromed center pieces of the Esky roof rack because it’s made specifically for hard-to-prime metals like that. The other one was their high-build primer for plastics and metals that I used on the chromed plastic strips in the running boards. I used that because the chrome had bubbled up in places and also it was dented and damaged in a couple spots from being hit with something so when I sanded those areas with 80 grit, part of the chrome sanded off and exposed the bare plastic. I have found the chrome layer wont feather when sanded so it leaves abrupt edges where the bare plastic spots are. I sand the hell out of the chrome with the 80 grit and be sure all the edges are adhered good, then I sand the best I can with the corresponding grits along with the rest of the piece. If I was to primer it at that point with regular primer, it leaves a lot to be sanded out. But the high build stuff lays on heavy and kind of self levels so there was almost no sanding and the primer layer looked perfect, the ridges were gone. Here’s a pic of where the plastic chrome was peeling and I sanded the hell out of it but those little pieces wouldn’t sand off and if I kept sanding it would look worse because the bare plastic areas would sand down before the chrome bits would come off. So high build primer and it looks great, no ridges no evidence of those uneven areas.
Edit:forgot to mention I used the Upol adhesion promoter on the plastic pieces before the high-build primer.
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