Please don’t take this as not listening to perfectly good advice, but I’ve been burned by that 2x before. Once was a long time ago with etching primer where I got the response from a body shop supply and a guy that worked at a body shop “use this etching primer, once it bonds to the surface you can leave it just about anywhere and it will be fine.
The second time, slightly more recently was in the mid ‘90’s when I started a project like this while I was in college on my daily driver (I really have no issues with driving a primered car… bondo’ed is a problem but not primered) while my parents were going through a divorce and in the process I lost a place to consistently work on my car. That time I was told epoxy is the way to go, it will protect things till you have time to finish it. Well, literally the next spring (maybe about 5 months, and we don’t have harsh winters around here in the DC metro area) a good 2/3 of the hood was showing the beginnings of rust coming through it.
DP90 used to be the “if you want to leave your car in primer but not have it fall apart, it’s waterproof” answer, and I believe it’s an epoxy primer that has been around at least a couple of decades now, but now you’re finally getting “well it’s not really waterproof.”
To be blunt, this thing will see 2 (or with some bad luck 3) years of race car and occasional street use before it gets real paint. I don’t have enough garage space to keep it locked up/covered up, but it will spend some time in the garage having a drivetrain swapped and roll cage installed (I see no reason why I would want the body perfect before I finish those anyway).
Unless the epoxy primers have _really_ gotten that much better in the last 10years, I don’t think I’d trust it to “sand it down, fix any other dings/dents, seal it and shoot it…” a couple of years from now. I’d be worried that the epoxy would have broken down/absorbed enough water that, well “lets take off all of it and redo all the body work that I already did.”
That brings me back to my thought process. I know that something like rustolium is and “industrial” paint and not necessarly compatible with automotive finishes, but as far as I can tell it’s basically an acrylic enamel, which I believe I should be able to get away with spraying using my HVLP, and then a couple of years from now I should be able to give it a good sanding, seal it with a sealer or some reduced epoxy primer and then shoot the car.
The last time I talked to someone about my last adventure with this kind of thing and epoxy primer, he suggested that what I should have done is after I primed it I should have gone to the bodyshop supply and gotten some “cryl” sealer tinted to something like the final color, shot that over the primer as a top coat and left it and it would have been fine. Best as I can figure out, ‘cryl’ is just another acrylic enamel?
I guess what I’m getting at is that if you’re really convinced that one of the epoxy primers out there, I’m guessing applied as a sealer, would adiquitely protect the finished bodywork under these conditions, that I’ll go for it, hell, it saves me at least one, maybe more steps, but I’m sure that I’ll be stressing about it the whole time…