When I reworked my roof seam last summer, I welded where I could, filled the small seam that was left with a thin coat metal to metal, and then toped it with a glass coat which worked great and is hard as hell to sand by hand but worth it like said above. No problems yet! The glass stuff is really impressive, and like said above Evercoat products are a world above the old Bondo stuff from the 70"s!