[oldchevynut]

I have never used POR-15, but I have used Masterseries coatings extensively due to it's better reputation as stated above, and to the best of my knowledge they are similar products with similar prep requirements. The blasting does leave a surface with plenty of profile or "tooth" for the coating to adhere to. However, if the sandblasting has been done with sand, there is a lot of free silica from the sand embedded in the metal, creating adhesion problems for the coating. The cure is to treat with metal prep to remove the silica. For that reason I have switched to crushed glass for blasting, as it supposedly does not leave any silica embedded in the metal, eliminating the metal prep step. So far, so good. Only time will tell. Randy