Tuesday night: Fine wire wheel on angle grinder. Pretty slow going, and it tended to take the yellow paint almost as easily as the purple. The angle grinder also overheats pretty quickly; I’d need to cycle through maybe four to be able to run continuous duty.
Thursday night: Heat gun and putty knife. The heat gun softens everything and it’s hard to keep from scraping right down to bare metal, much less to leave the yellow paint.
Removing Van Rust
Friday night: Coarse wire wheel on the angle grinder takes the rust right off my old van! Saturday morning: The rain puts the rust right back on! That’s okay; I can go back (Jack) and do it again, and it’ll take much less effort to get the light surface rust off than the heavy stuff that was there before.
Arly’s Advice
I just talked to Arly Funk, a wonderful gentleman who’s run a body shop in Newton all my life and will never retire; and he told me several things I don’t want to hear.
The original primer and paint are better than anything I’m going to be able to put on.
The house paint — even if not so sloppily applied — absolutely has to come off. It won’t adhere well enough for the next layer to last long.
Primer is not weather-resistant and is damaged by moisture. Anywhere I expose the primer, I need to reprime.
Anywhere I expose bare metal, I have about two hours to prime it. Beyond that, invisible oxidation is already forming and will weaken the bond between metal and primer. A light sanding with fine sandpaper is enough to clean this off before priming.
Out of curiosity, he has tested both hardware-store spray paint and roll-on liquid paint in his shop. Neither has good adhesion and longevity. In his experience, only liquid paint applied with a high-volume / low-pressure (HVLP) spray gun works well.
Sigh.