What's the best number of grit sand paper to use to get the rust off! I started with 120 then went to 300! Looks good but I want to make sure I'm not messing things up for later!
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bowtie36mc

After 300 I'd go with some 600 then primer

I wouldn't go any finer grit than 150 before primer. The first coat has to have something to grab onto. I'd also use epoxy or self etching primer for the first coat then follow with a two part urethane primer/surfacer to block sand it nice and straight.

When sanding rust, its hard to get all of it off unless it's just a light surface rust. Many times its pitted somewhat and you don't always get it all out by sanding. If you don't it will come back later. When I sand rust off I always wipe the metal down with Rust Mort or another rust conversion product. That kills the rust (converts it to zinc phosphate) and it won't come back.

Here's a good article on sanding that was a post on RRT by a good painter with lots of experience that I find to be real helpful. http://brunson.hypermart.net/prep.html
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George
DSRA member

This thing has been in a creek bed for 20 yrs. so it's bad but it coming along slow but sure the places I've done looks good! Just did passenger door today! So I'll check out that web site! Thanks!
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bowtie36mc

I was at the welding suppy yesterday and saw a scotch pad type disc that you put on your grinder for rust and paint removal. Could be worth a shot. Beats manual labor. Dave
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Life's too short to drive an ughly car!

GET in touch with our resident instructor TIN BENDER he's teaching classes . How about it ERIC
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Smoke um if ya got um
Burn Out Bob DSRA member

Purple pickup has the right idea. Don't go too fine. I use the 120 on a DA for the final sand on bare steel that will get a primer surfacer after the epoxy primer. I have a little trouble trusting the conversion coatings, but have never had any problems with them. I'd just rather remove the rust if at all possible. There are alot of abrasive disks avalible. The "rice cake" type work good but are expensive. Use them for surface prep, not paint removal. There are also several rust removal products that are acid based. I've used some with good results, but there slow and labor intensive. Use care not to get them into seams and crevices where they can't be removed. Whatever product you use READ AND FOLLOW THE DIRECTIONS! And with any type of sanding, keep the speed down, to prevent heat.

If its that bad why not do an alkaline dip? No amount of sanding and rust converter is going to equal a good dip.
Get it down to bare metal, flushed and dried well and then flood the blind cavities and lapped metal areas with the converter.
Finish the exterior surfaces as required by the amount of pits uncovered.
Done carefully there wont be any problems for 30+ years; lots of the big buck classics use the process. And rust converter wasnt available then, we just used gallons of Rustoleum primer and color coat in areas that wouldnt be seen or touched by the exterior finish. By "we" I mean I helped out a few pros who did primarly Senior series prewar Packards and Caddies back in the 60's. They were neighbors back in Lexington, Mass. and tolerated my hot rod inclination. I got to do work in exchange for a nice shop to play with my toys.

Note I said alkaline, NOT acid.
Do it in your pool if you get the wife away for a few days.


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Carl
Automotive gold is everywhere; you just have to learn how to dig for it

I sandblast all my panels to remove rust and all of the existing paint. Then I shoot dupont etch primer on everything. Later on I come back and grind everything that needs filler, fill all dents, then shoot House of Color epoxy primer on the entire panel,covering the filler with 5 coats and the rest with 3 coats. Then I block sand with 280 grit wet or dry and apply a 3M spot filler to the remaining low spots recovering them with epoxy primer and doing the process again until everything is nice and flat. Lots of work but the final product is sweet!
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Cap'n Kelly