Zero Rust is a strong as the surface you apply it to. It is recommended that you remove all loose, scaley rust. It must be fress of oil - clean it down with lacquer thinner or the like. I've used it on my '51 over what I would call tight rust, meaning that it doesn't flake off when I run a hand over it. A wire wheel will do the job for sure. They figure 3 mils thickness, which is usually two coats as each coat usually 1.5 mils. If you shoot the first coat too heavy, it will take a long time to cure. My routine is first coat, wait a day, (a shorter period in warm weather) then the second coat. Use contrasting colours when applying the second coat so you can tell that you get into all the tight areas. They say Red Oxide and Black are the best to use for the first coat.
