The Stovebolt Site Forums The Shop Area Paint and Body Shop Epoxy Primer Question

Hey guys been a while since I've been on forum. I am in process of doing frame up on my 52. This project has been ongoing for several years as I don't have 30 guys to help with rebuild as they do on Television:) and I'm buying panels as I can afford them and have time to do the work. My truck is setting in covered shop but exposed to outdoor elements at times. The panels have black semi glass primer from dynacorn which has faded in time. I want to use epoxy primer as I hear good things. I had someone tell me that I would have to sand these panels to bare metal to do this. The areas that I have sanded to weld show no signs of rust under primer....any suggestions or ideas? Thanks in advance for any imput!

An amateur's suggestion:

Either:
- strip to bare metal; or,
- scuff/sand all existing primer, and sand-away all rust.

Then, clean/wash with paint-prep solvent. Then spray with epoxy primer.

I'm going with TC's option #1 as a good epoxy hard to beat and you can't beat a good epoxy on clean metal for future protection, it's moisture barrier (rust encapsulation) chip resistance and adhesion abilities being the 'Base' reason for me.

Thanks! I guess my next question would be how long could primer set (Months?)before being painted? Won't be ready to paint for a while but want to keep things protected and rust free until I take it to the pro's to paint.

The primer can sit/set forever; and, as long as there is no rust under the primer, and as long as the primer surface is not physically damaged (scratched or scarped), that primer surface will last a very long time (and it will stop rusting of the metal under the primer).

However, after the primer is first sprayed on, if you do not spray the next coat within the recommended time-period (usually a few hours to a few weeks, depending on the primer), you then have to scuff the surface of the primer before painting on the next layer/coat of paint.

Thanks guys, Lots of good info as always!

Epoxy will last for years as long as not it's not sitting in direct sunlight long exposure to UV will degrade it.
We have some model A parts that have been sitting for 30 years with only the red oxide epoxy primer and still no rust threw.

I'd just add that when TC says "scuffed" it means with at least p180 or lower. You want plenty of bite for the mechanical grip if you wait more than a week. Less than a week still has chemical grip though I still scuff after 3 days anyway.

Another related question. I have heard that you can body fill over epoxy too. Is that true?

Now you've done it... you would have to open THAT one back up

The simple answer is, yes you can, but Pleazzzzze don't ask which way is best

Oooops tender subject. Je m'ecuse.

LOL, Not really 'tender' Super but Over or Under each has it's camp followers, Us and Them, Mine and Yours, This and That, and all their kids to boot... and they just went to bed sometime last week agreeing to a non committal truce that each is 'right' given a varied set of of undefined exceptions.
Fillers are 'plastic' epoxy isn't.
Fillers can absorb moisture epoxy doesn't.
Other primers are also moisture absorbent as well, relying on the top coat to seal them.
If your working in production or are just that fast with your projects that moisture over time isn't of concern I don't see a difference but if your like me and take a while between stripping and paint the epoxy offers some peace of mind as to whats going on with the metal I took forever to expose in the first place.

But that's coming from an avowed evangelical pagan...

I dont really agree with the above statement. Epoxies are usually considered plastic. I am in the epoxy prime first, plastic body fillers second camp. I also think scuff with 180 is overkill. In my tests and experience, a red scothbrite pad is sufficient. Dont want to start a new "war", so be safe and scuff with whatever makes you sleep better at night.

It's all plastic, IMO-both epoxy primer & body filler have two petro-based mixtures which chemically cure when mixed. Both stick like crazy to anything-I gotta chisel bondo off the dirty floor where it falls, and epoxy primer overspray sticks to anything/everything in the shop.

I've done both, and both methods seem to work. I do like the epoxy for those projects that linger-a buddy has a 51 epoxy primed as a finish, has held up very well parked outside and driven down dirt roads.

I have only used epoxy primer on my tractor. I just heard that epoxy was a great primer and I only had to use that and my top coat. I am such a novice that all the other primers confuse me. In that, there seems to be a filler, a sealer, an etcher, etc. etc. I don't know when to use each type. So I just shot the epoxy, then the finish coat which was just the AGCO enamel that is suppose to be for my Oliver. Definitely not automotive quality, but it's a tractor.

Now as it comes to epoxy, I bought PPG. I forget the numbers. I know that it is very important to wear a good respirator. And I spary outdoors in the open. I have seen that places like Summit also sells epoxy. Is there one that is safer to use than the other or are they all pretty toxic?

I will be ready to paint my cab and doors this summer when the weather warms up. So I am sure I will be coming on here for more advice.

Cheers.

While all epoxies may not be equal they are all the same... sort of. I think it works great as a replacement for the high build and other primers. 2 coats of high build is maybe three of straight epoxy, so you are using more but it's all one product which I think means better adhesion and chip resistance built right in...