The Stovebolt Site Forums The Shop Area Paint and Body Shop Rust converter and bondo?

I need to repair some rusty areas on my door. I usually just clean and spray it with rust converter then paint.

But the door needs some bondo on it. Is it ok apply bondo over the rust converter?
Thanks

Some people will say yes and some will say no. My opinion is yes. Especially if you are able to reach both sides of the rusty areas. Another thing I've done is to get some common enamel paint (in a can...not spray-on). Something like Krylon or Rust-O-Leum and then pour some inside the door...maybe 1/4 of a cup to cover the solid side (the side facing out). Color doesn't matter. Just be sure to get oil based enamel. Lean your door first one way and then another until it runs to all edges and into the seams. You may need more than 1/4 of a cup...that's just a starting point. Once you have everything coated, set your door on a couple of sawhorses and leave it in the sun for a day or two. When it is all dry, remove the lock and window regulator from the other side of the door, tape some plastic over all the access holes and do the same thing for that side. Then when that is dry, seal the 3 drip holes in the bottom and do the same thing for the bottom. Usually you will have coated the sides by doing this but look in there to be certain. Then...once that is good and dry I get a small tube of a caulking product like Alex caulk and I run a line from about 8 inches up on each side and all along the bottom seam. Just to be certain no water is going to make its way into that seam again. If you do that, your door will remain rust-free long after we're memories only. Good luck!

Jon's approach is pretty extreme, but a good one.

As far as bondo over rust converter, as long as the coating is secure to the base metal (you did remove as much of the rust as you can, right?) then bondo over it would be OK. Most filler instructions say use 80 grit sandpaper first to give the substrate some teeth. That would apply to rust converter or any paint layer as well.

Thanks for the help guys. It’s been a while since I’ve done any bodywork.

My approach would be to hit it with 80, then 220.
Blow it off and wipe it down with metal prep cleaner degreaser stuff. Then I spray rust converter. Directions say it likes a little rust.

Then I would apply bondo and finish. Sounds like it’s not the best way, and I get that. But this is on my sons 91 blazer and my objective is better is better 😊

Thanks again.

Don’t know why you’d need the 220 on any areas that will get Bondo.
The more mechanical bond the better.

Back in the dark ages when I was teaching collision repair, we used a 40 grit sanding disc to bare metal before applying Bondo to give the metal some "tooth" for the Bondo to grab onto. Fill, then sand, prime, and paint. Maybe old school, but it worked well!

Thanks guys. I’ll be tackling this next week.