This Mustang is completely primed inside and out with the Permanent rust sealer primer to minimize comebacks. Vintage cars of South Carolina has done this for the last 20 years or so. This procedure is as follows 2 coats the Permanent Rust Sealer followed by epoxy or urethane surfacing primer, something sandable. There are companies in the hobby that sell small amounts of industrial coatings for restoration work. I was affiliated with a couple of these companies prior to my retirement so I hesitate to name brands.