Have you guys had any luck with the metal lab fillers (or something else) to fill in a surface before you coat it? I have a cast aluminum magneto cover from a motorcycle with a 1/8" deep scrape. The scrape is about 2" long. I want to fill it before I dust it - but I want something the powder will stick to and that can take the heat. I noticed they make a high-temp version of the metal lab filler, too. I'm sure this depends somewhat upon the gun, and I'm using a basic one (not a Kool Koat that can do a beer bottle). I'm using Eastwood powders. Any thoughts?