Looking for some info on paints/primers

[firebob]

I'm about to the point where I'm going to paint the floor pans and the trunk pan. I used a rattle can etching primer and I'm going to top coat with Omni 2.8((MTX#1,MH238 Hardener).
Is there anything special I need to do to the primer before I shoot the top coat?

The paint shop said there might be a problem if it were the 2K but the rattle can stuff should be fine.

Also, I have a quart of Epoxy Primer(DP48LF, catalyst DP402LF) and a quart of PPG JP205 poly filler/primer.
Is there anything special that I need to look out for as far as what I can cover with it or anything I need to do before top coating ?

Thanks if you can help with info. Just don't want to shoot and end up with some weird reaction.

Robert

[elitecustombody]

If I were you, I'd completely remove the rattle can junk,wipe,blast,sand,whatever it takes, and spray epoxy primer or Rust Bullet

[JRouche]

Was the rattle can primer applied to bare metal? And was it a very thin coat? If not then it should be removed if you want a secure coating.

Etch primer doesnt have any solids in it. So it lays down very thin. So folks tend to over coat it looking for coverage and protection for the bare metal. Problem is. It doesnt protect the metal from rusting.

So there is usually an over coating of etch on the metal that has allowed corrosion to start under the very thick coating of etch primer. Hidden by the color of the primer.

Etch primer is just that, a primer. Meant to be used on bare metal and top coated with another paint very soon. Its more of a chemical reaction then anything. Its eats into the bare metal and provides a good bond for the next coating, which should be applied while the etch is still clean and semi active.

If some time has passed since the etch was sprayed then more then likely it has deteriorated to a dry, loose "dirt" that you dont want to put any other coating on. It is no longer a primer for paint but a dirty surface that needs to be removed.

Worst case is it was sprayed onto another paint or primer. Then that was a waste. It needs to go on bare metal. And re-coated fairly soon.

The good side?? Rattle can etch is easy to remove. Yup, no solids to gum up the sanding pads. And because its not a very good protectant it deteriorates pretty fast. And it comes off with a scotch bright pad on an angle buffer. USE a quality dust mask. You dont want to be breathing in that dust.

Because its on the floor and trunk I would just buff it out with a course scotch bright pad. That is if all you are looking at is the etch primer then bare metal.

If it was sprayed over any other coatings then you are in for some work. It compromised the coating it was sprayed on (the acid in it) and all of it should be removed. And I say should be removed but what Im thinking it doesnt have to be completely removed. Its just the floor.

If it was sprayed over another coating of paint then I would get in there with my 9" grinder and a wire cup and remove what comes loose. Not trying to get to bare metal. Just trying to remove all the loose parts. Then,vacuum it out, blow it out with the compressed air, water wipe it down then solvent wash it with some acetone. Ready for a new coating of your choice. JR

[firebob]

Ok so here's the deal.The floor pans were very rusty w/a few rust through place and pinholes. I scrapped and wire wheeled removing everything loose or crusty, scuffed up all the existing paint with some 120, RustMorted and Por15'd the rusted areas. Let it get tacky and fogged it with the etch. The after the p15 sat overnight shot a good cover coat over the whole floorpan with the etch primer. Seems like it stuck. I'll try to sand a spot off tonight. See if I can tell. It's sat for some time now so maybe needs to be scuffed and covered with some other type of primer? Sounds like you think it would be good over bad.

Robert