Which goes on first? etch primer or filler... for bare metal prep

[GarageStudios]

Team,

I have been reviewing many, many articles, forum posts, videos on what steps "should" be done when having bare metal prepped for painting.. The goal is to prevent rust from forming, and trying to make sure the car lasts with a good paint job..

As I reviewed, some etch primer the bare metal first, then perform body fill, fixes etc.. then use some type of epoxy primer then sealer then more primer of 3-4 coats then continue on.. Others, body fill first, fix etc, then epoxy prime etc...then seal, then prime...

I just wanted to make sure that my bare metal was rust proofed before any painting.. sealing the metal because I would hate to rebuild my project again , any thought and advice greatly appreciated!

Here is what I read on both etch and epoxy... Im just confused on the order of prep n paint... and what is best practice..

Self-Etching Primer

An etching primer uses an acid to chemically clean and micro-etch the metal surface for a better mechanical bite to promote adhesion with the layer of high-build primer to follow while also providing a layer of corrosion resistance on the metal. Because it cures quickly, it’s the method of choice for collision shops. But a key difference with etch primer is that you need to apply your filler or bondo first directly to the metal before spraying it. An example of the application order on bare metal is: 1) bodywork including filler/bondo 2) paint prep solvent 3) self-etch primer 4) high-build primer 5) basecoat 6) clearcoat.

Epoxy Primer

As the name implies, epoxy primer gives you excellent adhesion, similar to applying epoxy glue while also sealing the bare metal from environmental elements. Since it relies on forming a mechanical bond with the metal, you have to manually create the bite it needs by sanding the entire surface of the body with 80 to 180-grit sandpaper. Once the epoxy primer is down you no longer have to worry about rust while doing your repairs – especially since you can apply body filler right on top of it. Then simply respray the areas you worked on to re-seal them. Although it takes longer to cure than self-etch primer, restoration shops tend to favor epoxy primers because of they often handle more extensive body repair projects. An example of the application order on bare metal is: 1) paint prep solvent 2) epoxy primer 3) bodywork including filler/bondo 4) epoxy primer on repair areas or over entire car again 5) high-build primer 6) basecoat 7) clearcoat.

Thanks in advance..

Edited December 17, 2013 by CDN224 (see edit history)

[Scotts_DG8]

Epoxy Primer An example of the application order on bare metal is: 1) paint prep solvent 2) epoxy primer 3) bodywork including filler/bondo 4) epoxy primer on repair areas or over entire car again 5) high-build primer 6) basecoat 7) clearcoat.

This is the sequence/steps that I'd been advised to follow and the one also recommended from the PPG paint store where I've been getting my supplies. I can say too that this approach takes a lot of work as you'll feel like you're doing a lot of repetive work. I also think that either approach would work for you it just depend on the quality and life of the end product that you're trying to achive. Scott...

[Guest rjones]

Been working a bit at a body shop lately and can tell you that he has a large selection of things to use. Many things do not go together and most take a certain order. If you are going to be the painter, then I would find the type of finished paint I wanted and where I was going to get it. Then I would ask their system recommendations and procedures. If you are having someone else paint it, I would find how they prefer it and what to use. Many painters will not paint over others' body work unless they know exactly what is there, how it was done, etc. Even then some will not paint over it at all. I know that is a lot of ahead planning but you want it to last and I'd hate to see you put a lot of work in it and have issues finding a painter or paint it yourself and the paint lift something underneath it. Either way, there are many good systems out there just try not to mix the brands!

[whtbaron]

x2 on that. Find the system that best suits the way you want to work and stick to the manufacturer's directions. I've seen too many jobs botched because of the old mix and match, although lots of painters will develop their own system that works over time. When you hear someone complaining about a particular brand because it chipped or pealed, chances are you are looking at a job that utilized multiple manufacturers products that were not used according to directions. Major paint companies don't stay in business selling inferior products. If your shop is subject to a lot of humidity, I would suggest keeping a primer under the filler.

[RansomEli]

You are getting great advice. Nothing I can add.

For me, epoxy primer, bodywork, more epoxy, surfacer and color coat is the way to go. Don't scrimp on paint. Depending on the color, expect to pay close to $1000 for primer, surfacer, base and clear coat.

House of Kolor had some good paint/restoration books. You might still find them in places like Barnes & Noble. The books (actually, catalogue-sized paperbacks) show you the "right" way to prepare and paint a car.

[Luv2Wrench]

I've found this thread very helpful. The site, autobody101.com has a very helpful forum.

http://www.autobody101.com/forums/viewtopic.php?f=5&t=16694&sid=53bcf55af08828422c37de5d8a22b66c