Fixing rust spot

[Mr_Incredible]

I have these rust spots on my truck's roof around and about the clearance lights. They suck.

I've found my best results come from sand blasting the rust out. It gets the rust without removing metal thickness. If you keep rusting, and keep sanding, the metal will get mighty thin mighty quickly.

Throw away the dremel and sand by hand, young man. Put some elbow grease into it.

Then you mask, then you prime, then you take the tape off and go out another 1/16th", then mask/scuff/paint, then go out another 1/16th", then mask/scuff and clearcoat 2 times.

...for best results....

 

[Californiabob]

you could also use a fiberglass pen (looks like light strands) and remove it gently. I used POR 15 also. The area I fixed was about twice as large as the OP's. After a second coat of POR 15 I used touch up paint to cover everything.

 

[gomes512]

The MSDS for that product shows some sort of proprietary organic acid but no phosphoric acid. It also has a proprietary polymer so it appears to be another sealing type product. Bet that organic acid just acts as an etcher so the polymers can attach better to the surface being treated.

POR15 and Eastwood's Rust Encapsulator are my paints of choice. But I always pre-treat with naval jelly or conc. phosphoric acid before painting.