Still confused on primer

[Nowik35]

Fellow EB builders,
I did read through a ton of the primer posts but I'm still confused on best approach for me. So I'm getting to the finish stages of welding up my body and will want to prime very soon (most concerned about interior) . In my case I have a combination of the primed panels bring welded to original floor. So my floor is a combination of surface rusted metal joined to primed metal, with raw weld all that needs to be most efficiently primed. Plus after wire brushing my bed, I'm to bare metal but some pitting is present from the rust. That being said I'm peter petrified of all this work and money and a year later rust poking through bc I primed wrong. Being on a budget I'm going the rattle can route but there's so many options. 2k primer, etching primer, automotive primers, filler primer, rust converter primer...... Which one do I use or in which order????!!!. I'm thinking etching primer over the weld, then 2k primer over the whole floor, them auto seam sealer, then filler primer, then 2k over everything one more time? Is that good, to much, wrong? Help please. Or did anyone just do 2in1 Rust-Oleum primer and filler right to bare metal and over the old primer, and welds and it should be good enough?

 

[Torkman66]

There are lots of opinions for this question but also some basic truths to guide your decision. First, you are EXTREMELY limited by only using rattle cans. What should happen is this:
1. Do all your metal prep including welding and rust removal
2. Spray any rusted seams or rusty areas that are salvageable with phospho.
2a. Do all bondo body work on clean metal surfaces.
3. Paint everything top to bottom with 2 part epoxy primer. This will seal out moisture and keep it from future rust.
4. Seam seal all joints with paintable automotive seam sealer.
5. 3 or 4 coats of 2k high build primer for blocking.
5a. May need to do this step twice depending on how nice you want it to turn out.
6. Top coat.

However, if only using rattle cans, you have a few options. Eastwood makes a 2 part epoxy in a can that you should spray on all welds and seams. Then use seam sealer on top of that. Now you will be pretty good regarding rust. How you go from that point with rattle cans is an unknown to me.

I am a big fan of Rustoleum products. It takes a long time for it to dry hard (couple weeks) but if allowed to cure it’s very good. You can do a good job painting the underside and the interior floors with Rustoleum tractor paint. 1 gallon is about $50 and if you add the pint of hardner it is extremely durable. It also drys very flat leaving almost no brush lines. Have used it this way underneath and on floors.

 

[duffymahoney]

If I started my bronco over, I would have done powder coated primer. So blast, rust repair, then back to the blasting shop for powder primer. The whole body, doors, hood, tailgate. It's how ICON and a few other shops do it. I have done it on a few projects now. I love how strong the bond is to the metal, and how it can get into any nook and cranny.

 

[Broncobowsher]

High build primer is a little misleading in name. Think of it as a sprayable body filler. Primer in that it goes between the metal and the paint. But the main purpose is to have something sandable, fill in the low spots the grinder left in the metal.

As for materials, not all of them are compatible. Need to start with the finished paint and work backwards with compatible materials to know the primers to use. There may not be a spray can of primer compatible with the final paint. I had a gallon of material, after talking with my painter I ended up giving the stuff away and got a different gallon of material that would be compatible with the finished paint. Sucks, but a decade later the paint is still in great shape.