Epoxy Primer over Self Etching Primer (laquer based) [Archive] - Chevelle Tech

: Epoxy Primer over Self Etching Primer (laquer based)


chevychad
Feb 3rd, 10, 4:14 PM
I stripped most of my chevelle to metal, put on a coat of self etching primer (laquer based). Thought I was putting on epoxy primer. (rookie mistake) After I started on some body work to smooth out the weld spots. I realized it was not epoxy primer, by looking at the paint can more carefully.

Can I epoxy primer over the self etching primer? Or do I need to keep going with the self etching primer? or strip and restart.

I hope I didn't mess up the process.

TechNova
Feb 3rd, 10, 4:20 PM
You are not supposed to put epoxy directly over etch.
You should also not be putting filler over etch, not sure if that's what you meant by "bodywork"

chevychad
Feb 3rd, 10, 4:54 PM
yes I put rage gold filler over etching primered panels. Do I need to strip it back down to metal, then epoxy prime, then filler?

BlueSS454
Feb 3rd, 10, 5:45 PM
yes I put rage gold filler over etching primered panels. Do I need to strip it back down to metal, then epoxy prime, then filler?

That's what I've always done. There really is no need for etching primer over sanded bare metal when epoxy is available.

chevychad
Feb 3rd, 10, 8:17 PM
The can says, over bare metal, over primer, under primer or paint. Is that stuff just old technology that is not recommended anymore? I don't understand why filler should not be over it?

At the same time I want to make sure I don't cause future problems with the paint.

pglade
Feb 3rd, 10, 8:57 PM
Sure---etching primer can go under paint...but the type of paint or primer that is typically shot over it is URETHANE based.


As already mentioned...no epoxy and no polyester fillers on top of etch primer....take the stuff off. You said you want to avoid the possibility of future problems, right???---the only way to eliminate the chance of a reaction is to GET THE STUFF OFF OF THERE!


or---roll the dice and leave it on there.

Hmmmm....which odds sound better???

crazy canuck
Feb 3rd, 10, 9:09 PM
The reason why you don't want to put filler over etch primer is the acid in the etch will soften the filler causing it to lift=failure and redo.Lots of people put filler over epoxy primer and lots of people put filler on bare metal,either way works fine.The funny thing is all filler manufacturers recommend putting filler onto properly prepared bare metal(I have done it this way for 25 years with no problems) but only paint companies recommend to epoxy your panel before filler.(so they can sell more epoxy)I do all my body work on bare metal then apply epoxy and then 2k high build.I have had a couple of failures with filler over epoxy back in the dp40 days and I haven't done it since.

john5469
Feb 3rd, 10, 9:18 PM
So what the heck is self etch primer invented for?

pglade
Feb 3rd, 10, 10:00 PM
speed...collision work, etc.

chevychad
Feb 3rd, 10, 11:06 PM
I am glad I found this out, from everyones advise, before I went any further with the body work. I am going to strip it back down, then epoxy primer.

In all reality, I am not very far yet so it is better to start over. Thank you for straightening me out.

You guys are the best!!

Rucumn
Feb 4th, 10, 8:11 PM
There is very good reason to use epoxy directly on bare metal and then use filler over it (per the specifications). It is not just so the paint companies can sell more epoxy, but I am sure they do like selling stuff too.

TechNova
Feb 4th, 10, 9:08 PM
So what the heck is self etch primer invented for?

Self etch has excellant corrosion resistance, you just can't use filler over it. While it is much faster for collision work, it does not mean it is a poor product. I have used it thousands of times, in fact, part of my car has etch (wash actually) and part has epoxy. The epoxy was used because I stripped some areas and wanted to get it in primer so I could finish fill a few minor imperfections a few months later, not a good idea with etch.
The areas where I was stripping, filling and priming an individual panel all at once I used wash.

BIGBLOCK70Z
Feb 4th, 10, 9:20 PM
etching primer is and was invented to go over bare metal, so the urethane primers would stick. epoxy has etch built into it. and has a 98% moisture:thumbsup:

72soft-top
Feb 5th, 10, 12:00 PM
I use etching primer on parts like engine pullies and brackets where no filler will be applied.

Badboyvince69
Feb 5th, 10, 12:49 PM
Is self etching the right one to use to cover bare metal until i can get the car to someone to paint? I have been taking off the rust, and body filler,then covering the bare metal with it for protection. I know epoxy is the best to use, but i wanted the body work done then covered with it.

casey2020
Feb 6th, 10, 9:40 PM
Taking a car to a painter i would much rather have the epoxy on it!! epoxy is used directly over bare metal and is for corrosion protection. Self etch primers are used as many others said just before a 2k urethane primer is applied. Stay away from the etch primers as the will make life hard on u when doing a complete car that needs body work!! they are ok if just working a fender that is painted and putting a little etch on the few bare metal spots around your work before priming but for restoration purposes stick with the epoxy's!

pglade
Feb 6th, 10, 10:06 PM
Is self etching the right one to use to cover bare metal until i can get the car to someone to paint? I have been taking off the rust, and body filler,then covering the bare metal with it for protection. I know epoxy is the best to use, but i wanted the body work done then covered with it.

Not if the parts are going to be sitting around for any length of time...metal with etch primer on it will still rust pretty quickly if there is any humidity, etc.

It's made to be shot on the car and painted over. It's a primer FOR A TOPCOAT....it's not a good "storage" type barrier at all IMO.

A lot of people have misconstrued what "etch primer" is all about---mainly because of the name of it I think. They envision spraying this stuff on and think the acids in it eat away rust, etc......not so. The stuff is basically only as good as the metal below it and as mentioned above, it doesn't serve as a good barrier between the metal and the environment.

Put a good epoxy on there.

Badboyvince69
Feb 7th, 10, 11:50 AM
Thank you very much for the info. I will take the etch off.