That's fine with a standard epoxy primer. Do not coat a part you know you'll have to work on later with POR15 though, it basically requires a grinder to take it off. Sanders and sandblasters don't touch POR15 once applied. Any of the epoxy or urethane primers hold up against moisture for extended periods (though you'll probably have to scuff/clean them before you shoot a sealer/basecoat).

-Kustomizer

From my understanding on the subject, No. If it is exposed to UV, it will chalk over time, but should be good with a scuff and recoat.

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Exactly Right on the epoxy.

2K primer is made with different types of talc IE: course, medium and fine chromium. If it will protect the metal exposed to the elements depends on how its made and blended with the different grades of talc. Some will be fine for 6-12 months some won't. Its guess by-golly!
Barry

Do you have to get all traces of the black coating that patch panels come with off before epoxy priming..or is it ok to scuff, fetheredge and shoot right over those areas?

If you're talking about the black primer on new metal parts, it's generally fine to cover-over with a self-etching or DTM primer... once you've degreased it (many times they have an oily coating on them). If the solvent you use to degrease the part takes off the primer, then you know it wasn't strong-enough in the first-place.

I've done a bunch of plastic parts (bumpers, air-dams) that have this blackish-primer on them, but the degreasers wash that off like it was soap. In that case, I always use lots of cleaner and rub the primer off (don't sand primer off plastic parts).

-Kustomizer

think it was skipped over, but what do you need to do to scuff the epoxy for a recoat?

and if it has chalked does the chalky layer need to be removed, or just scuffed and coated over?

I always scuff primer coats prior to seal. I always wait to seal until just hours before I shoot color.

If you waited long-enough for an epoxy to chalk (POR15 is the only one I've used that chalks, the Dupont DTM doesn't), then you've obviously waited long enough for dust/dirt/oils to collect on the surface. Simple degreasing and cleaning prior to seal will get rid of any chalking, and you have to do it anyway.

Good luck!

-Kustomizer

I don't think I answered your question... I use 320 or 400 wet if it's a part that I don't mind water (like a panel where water can escape, so it doesn't pop-out when hit with the gun), or-else I use a green or brown 3M Scotchbrite pad dry. If you scuff dry, you'll have to wipe-down with something like laquer thinner or a typical degreaser/cleaner.

The point of scuffing is just to break the surface up a little, you're not trying to sand or grind here. Increasing the surface area gives greater strength to the sealer. Best rule of thumb... if there's a reflection, you need to get rid of it!

-Kustomizer

I agree with the scothcbrite recommendation. The only difference is that I use the more common (red) or medium as it is commonly known. I think the 3M part number is 7447. Been awhile since I have ordered cases of it though. You can often find single red pads in hardware and home stores. I believe Barry K uses the red as well. I think anything that gives it a light roughing (scuff) would do the trick. I like the scothchbrite because it easily conforms to door jambs and irregular areas and no need to worry about water entrapment. I'm not a pro though, so?????

Kustom thanks - Ok so traces of the black coating are ok. How about traces of filler...ie bondo..can you epoxy prime that too ?

Keith

Absolutely. In fact, you almost always have to, since the sanding-process of taking-down the filler will scratch-through to the metal somewhere. That's where the DTM epoxy shines, since it etches into any exposed metal.

Good luck!

-Kustomizer

So this is my first post to this forum. Wow! Huge amount of great info. This is great!

Anyway, I wanted to jump right in on this thread because I have a question that fits right in. I think that it has been answered in part already but I want to be sure.

Is epoxy primer what I should use if I need to cover bare metal and I do not intend to top coat imediately?

I am doing some exploratory stripping of a car to see what I am dealing with and don't want to end up having a bigger mess than I have now in a few months because of new surface rust. I understand that most primers will allow moisture to get to the metal and I certainly do not want that.

If I cover with epoxy primer, will the metal be protected until I can go to the next step? (I do realize that it will not protect indefinately)

Any input would be appreciated!

Yes! On all accounts.

Your easy!

Welcome aboard!

I used the ppg epoxy primer, problem is that it has been a couple months since I sprayed it - do I need to reapply before I do my color coat or will it still "stick"?

I see this was just answered a page back but what can I say - I need reassurance

I have more epoxy primer to respray but it is all good to go and I have a small window to paint with, rather not have to prime again, clean gun, spray. Rather just get to it but I don't want to waste my time..

The paint going on the ppg dp40 (I think) is an omni single stage..

I believe the tech sheets say to scuff and respray after that long. I myself would scuff, 2K it, level and paint. You could 2K it, level and paint it in a short amount of time. The Omni line has a 2K urethane primer. Let us know how it turns out.

check out the "oscar" thread. Yea, I shoulda 2k primered it all, I ended up with a couple "dimple dents" here and there that I didn't see in the primer.

I got 3 other vehicles in line for painting and complete buildup so learn a little here and move one. I may fix panels here and there later but I am going to put the car together so I can drive it (been a year and half).

I did respray the epoxy primer about an hour or two before doing my final coat "just in case"