Prep for epoxy primer

[TrackPack]

I planned on using SPI epoxy primer on my project but when reading through the tech sheet it says not to use over lacquer paint. Here's what I have to work with:

The engine bay - Someone sprayed flat black paint over the factory color. I think it is lacquer by the way it sands, I have sanded it off by hand but a fair amount remains in crevices etc. I had not planned on stripping the entire bay to bare metal, only where needed and then epoxy prime.

The trunk floor - Someone sprayed white paint on the floor and wheel wells. Tested a few spots and can tell that this isn't lacquer and probably not a primer either.

Body panels - Has a very old coat of gray primer over the factory color. I can tell that it was DA'd before primed with some small spot repair areas. This sands out like lacquer primer, and I recall that this stuff was used in the 80's quite a bit. Again, I had planned to block this old primer down (use as a type of guide coat?) and then epoxy prime, but didn't want to strip the panels completely down to bare metal.

My question is can I use the SPI epoxy over any of the lacquer primer that might remain? What about using it over the original factory enamel and primers?

If epoxy is out, what can be used in a situation like this?

Appreciate anyone's thought and experience on this.

 

[slimt]

Epoxy over primer will fail. Epoxy was designed to protect bare clean metal, the scratch in the metal should be 120 grit anything finer will shine the metal. And there will be no bite for the product. If your panels are primed and everything looks clean with no blistering of primer due to trapped starting to show signs of rust ,moisture on the metal to primer. Carry the process through. But if your unsure. Down to metal for epoxy is in my opinion the correct way then build up from there

Everyone has a different approach mine would be what I wrote. Edges or where. two panels meet together are the most important.

 

[snakeoil24]

Epoxy likely will peal off the substrate

 

[R413]

Lacquer thinner and a toothbrush and paper towels will get the old lacquer off pretty quickly.

 

[PurpleBeeper]

In general, as R413 mentioned, lacquer will come off with solvents and catlyzed paint (like epoxy or urethane) will not.

 

[TrackPack]

Lacquer thinner and a toothbrush and paper towels will get the old lacquer off pretty quickly.

Once the old lacquer primer is removed is it ok to apply epoxy over the original factory paint if sanded with 80 grit?

 

[snakeoil24]

Use 180 to 220

 

[zyzzyx]

Lacquer thinner and scotch brite will take off any inferior paints that are on the car, such as
what you have in the engine compartment. Epoxy primer is designed for DTM, or Direct to
Metal!

 

[TrackPack]

I hand sanded most of the flat black out of the engine bay, but there is some remnants.

 

[TrackPack]

Lacquer thinner and scotch brite will take off any inferior paints that are on the car, such as
what you have in the engine compartment. Epoxy primer is designed for DTM, or Direct to
Metal!

Since I want to leave (most of whats on the panels after the lacquer primer is removed) the factory paint and original primers do I need to use something other than epoxy primer?

 

[4speed68rt]

I would say it is best to sand it down to bare metal, especially all of the body. Then you will be sure that that expensive paint job will stick. You can always do less under the hood and behind the grille, trunk etc... Paint jobs are too expensive now days to try to not know what is under there, and it is hard to only take off the top layer of primer. Get a cheap hand held electric sander and some 80 grit discs. Sand it in sections and put on the epoxy primer as you go so it doesn't surface rust. Depending on what kind of car it is, it should all be worth it in the end.

 

[zyzzyx]

Use etch primer on all bare metal areas such as SEM Etch primer in a rattle can, then prime
everything with Evercoat G2 primer

 

[gkent]

Over the counter lacquer thinner is mediocre at best. The ideal stuff is what's sold in 5 gallon pails at paint supply shops known as "gun cleaner" (spray guns - not handguns and the like!) This stuff, while still exhibiting the characteristics of normal lacquer thinner, is much stronger. So much so that it WILL dissolve dried, catalyzed primers and paints.

 

[snakeoil24]

No etch rattle can anything must use epoxy on bare metal, etch primers are not compatible with any epoxy which is written in most epoxy products which are 2 part

 

[EARLY B]

Why do they recommend to use reduced epoxy as a sealer before painting????

 

[dadsbee]

Epoxy goes over this... bare freshly blasted or prepped metal... Don't forget the Wife's approval.. LOL

 

[gkent]

Why do they recommend to use reduced epoxy as a sealer before painting????

I was wondering this same thing.

If you shoot epoxy primer it'll give a thicker coat which generally requires sanding to yield a smooth surface. Yet not smooth enough for topcoating. So now you reduce the epoxy more and shoot the thinner "sealer". If satisfied you can paint within the allowable window OR give it a light scuff and topcoat at a later time.

Conversely on bare metal you could start with a sealer just to provide protection from flash rust and go back to it later to do you bodywork, bondo, etc..

A sealer uses less of the more expensive product since you thinning it out with reducer.

And those are what I've concluded from what info I've read. I'll tell you this, anything I ever epoxy primed then topcoated without any sanding generally looked like a pebbled finish !!

 

[Photon440]

As a sealer, it also flashes off and dries faster, if that's important to your job.

 

[Crowbar]

I would tape up all the holes on the firewall from the inside of the car and tape off outside stuff come back on outside stuff with duck tape like around cowl and other areas and would sandblast it then epoxy primer it All those little nooks and crannies will come back to haunt you if you don’t Then come back and primer with about 3 to 4 coats and sand You will thank yourself in the long run RC

 

[bandit67]

Why do they recommend to use reduced epoxy as a sealer before painting????

Many folks, including me, do my final block sanding with 400 grit. That is considered 'too scratchy' to some serious painters. The belief is a sealer smooths out those scratch swirls left by the 400 grit. I have used both, a sealer and epoxy thinned down to sealer use, with good results.