The Stovebolt Site Forums The Shop Area Paint and Body Shop What kind of primer after sandblasting/stripping paint?

I’ve got a 52 Chevy pickup that I’m planning to take apart, piece by piece, then strip the paint, do some puttying. Then I want to prime so they don’t get surface rust before I get them to a body shop for finishing (2 stage clear coat paint). I went online, and several recommended using epoxy primer; I went to a reputable auto paint store & they suggested etch primer – not epoxy as it is very hard to sand. The primer will be going over body putty – but I’ve read don’t put etch primer over filler. Any help regarding what kind of primer to use would be appreciated – I’m getting into information over-load. Thanks. Bob

Everybody seems to recommend the epoxy primer anymore. They tell me the self ecthing primer is more for the modern stuff with the zinc coated panels.
I know I questioned putting filler over the epoxy primer, which I've seen done. They claim it is okay to do this anymore. I had always read "old school" that the putty should be applied to bare sanded metal to give it some tooth to stick.
I guess maybe talk to the body shop you are going to deal with and see what they recommend and the brand paint they are using. Anymore they say you should stay with one brand (system) of paint.

John

If you are going to put anything on the epoxy primer, you have to do it in the recoat window. If your out of the window you have to scuff it, reapply more of it that is epoxy primer and then apply your what ever to it. And is a good reason to not bondo on top of it.

I am not a painter, but I work with a painter (and have hired professional painters) who all follow the procedures below.

Read the instruction sheets that should be provided with the paint (these sheets must be available/provided, or use another paint line)

If you have clean (blasted) metal, you can/should spray epoxy primer over the metal. There is no need for etch BUT wipe/prep the metal as described by the paint manufacturer (you can wipe with lacquer thinner, but carefully/thoroughly wipe off the thinner residue with a good quality (and recommended brand) of wax and grease remover. We use one-time-use, non-colored towels for cleaning/wiping.

If you do use self-etching primer, check the instructions regarding the need for an overcoat (like epoxy primer) in order to prevent rust.

Body filler, sealer, and surfacer can safely be applied over the epoxy primer (read the manufacturer's instruction/information sheets, to be safe about this).

All epoxy primers (that we have used) provide information sheets on how to scuff/treat the epoxy-primered surface after different periods of time.

Well it's a real political style debate that has no concrete answer.
Why I'm an Epoxy First Member:
I have pic's of rust growing under filler over metal on my truck from when I stripped it.

I use only epoxy primer for my build and sealer coats and it is EASY to sand wet or dry. And no need for a guide coat because the sheen/gloss does the job instead.

A panel sealed in two (or even better 3) coats of epoxy can sit for years and then just need some 80-180 grit sanding to cut the film and your good to go with your filler or to start blocking.No need to re-appply epoxy. A sealer coat is good to tie your filler/build coats to your top coats since most filler and build products are polyester based and absorb moisture if left exposed and it will also improve your top coat adhesion. Not really needed if you use epoxy for the fill cause its WATERPROOF.

Epoxy affords two types of adhesion. Mechanical and chemical.
If you stay within the re-coat time (5 days for SPI)you get both. If not you just get mechanical which is all your ever gonna really need. (Fillers don't chemically bond to metal either, which is why you need the grit.)
Etch primers have an acid in them to try and help but they don't play well with some of the major epoxy primers... So I just say, No thank you when they are mentioned.

I had always heard you should never apply epoxy primer over self etching primer..... Self etching primers are not very good for protection, moisture will woprk through them. When we used self etching primer on cars, we always top coated it with a high build three part primer. This was to seal the self etching primer and also for sanding down for the finish coats, which were usually basecoat and clear.
John

Some good points here. I suppose a person could do filler over the epoxy then re epoxy if you had to.
Rust under anything means it likely wasn't all removed or treat with something to convert it. And would in time have come trough epoxy too I feel.

A lot of folks are using a product called Icing for filling dents ect... on panels anymore. It is good up to about 1/8" thickness, feathers easily. Can be applied over the Epoxy Primer.....

John

I should have been clearer about procedure maybe...
Yes I apply more epoxy over the filler. Anything that might absorb moisture gets epoxy over and under.
As I stated earlier I also use the epoxy for my 'high build'.
3 epoxy = 2 normal build.
As for rust under filler... I believe since filler is an exothermic reaction (gives off heat) the potential for water vapor to form and get trapped is/was the problem.
That and not cleaning the surface with a good wax and grease remover... I read recently a guy doing a new panel and stripped the factory coating (as a precaution) only to find rusty finger prints under it...