I’m pc ing my original 66 hub caps with ss chrome. I sandblasted with alum oxide, wire brushed smooth, used pre, dried and pc’d. I did a t fitting for the rag joint the same way and at the same time, it turned out fine. The caps had bumps or gassing problems that also looked like dust under the pc. I checked the pieces before pc ing and curing, they all appeared to be fairly clean. I cured for 30 min ( works better than 20 min, thanks 😀 ) checking the temp periodically. At first I thought the bumps or dust was just extra thick coating, but it never blended in. Should I have pre heated the clean parts first, to what temp, for how long and let them cool first or shoot it hot?