Originally Posted by Riot Racing
I considered that but kind of doubt this is what caused it. The first pieces I POR15 had this same issue and I only applied 1 coat of POR15 to that surface and the bumps were even worse than these pieces.
I used a wet rag to clean the sandblasted metal. I then used a Tack cloth once the metal was dry to make sure there was no contamination on the metal. I am skeptical that these bumps are lint.
You did not mention if you used sand .soda glass ,or walnut shells,on small panel such as the one in picture i have glass in my cabinent with no problems,also coat with por 15 ,i spray mine one coat only . i have seen good results with brush ,if uou used sand with silica it needs to be washed with dx330 ar similar prodect to remove silica ( posion ) when i use sand i use play sand ,non toxic leaves no residue,.possibly wiping with wet ,water ,rag you might be just spreading contaminates, ,there are many opinions ,this is mine after 40 + years.