It doesn't have to run any tools just a small spray gun at 3.6 CFM @ 40 psi. I tried to tailor this quick job to the DIY not having a big nozzle spray gun needed to spray bulk epoxy primer so for that we will use 2K rattle cans, to sand it an electric orbital sander will do fine and for the fine sanding a rubber block is what would be used anyway.
Start by washing the roof with Dawn and warm water, dry it. Using the orbital sander on a mid setting sand the rust spot and surrounding area with 80 grit. Once it is clean metal use a coating of Rust Mort on the area that had rust, this will get the smallest specs in the metal the sanding didn't get. Once dry sand the Rust Mort with the sander and 80 again. Feather the edges of the bare metal to the surrounding paint using 120 brit on the orbital
Scuff the rest of the roof with 400 wet and dry and water with a couple of drops of dawn in the bucket to prevent paper clogging on a rubber block.
You are just going to knock the shine off it not sand it to primer or metal, you can also use a red scuff pad dry if you want.
Wipe the roof down with IPA and dry it.
Mask up the rest of the truck, I usually use a large clear plastic drop cloth from Wally's and cut out the roof then mask it off at the top of the windshield/doors, etc.
Using the 2K rattle can of grey epoxy primer spray 2 coats over the bare metal giving it about 15 min between coats after an hour spray 2-3 coats of the black 2K Urethane primer over the grey epoxy. Believe it or not the priming with epoxy and Urethane is the most important part of the job, the paint is only as good as whats underneath.
Cheap rattle can primers from the local parts store are talc based and offer zero protection. It is common for people to repair rust, use filler and spray this over the repair only to have the rust come back in no time, the bondo and primer absorb moisture and the metal rust under the paint, sometimes you will see a bubble and when broken it is full of water. This is the reason, we use epoxy, it effectively seals the metal or filler from moisture. The Urethane is what we block sand to smooth and flatten the surface before painting, the color of the Urethane is important as it plays a role in the color match.
As we are using a rattle can with few shade choices on a dark color we go with the black, yellows, reds, white care use a white primer.
Let the primers cure overnight or longer, the metal is now protected from air and moisture.
If you are onboard so far let me know and I will make another post with the rest of the steps, this is really easy to do, dont be intimidated by the long instuctions, once you get started it will be easy.
