SPI Epoxy over PPG with Wash

P

portland

I have and plan to use SPI epoxy on a project I am working on. I have read however that you should never use etch or a wash primer under the epoxy. I think I may have a problem...current project was started using PPG wash primer and PPG DPLF. I am way beyond the 7 day re-coat window without sanding. Now if I sand this DPLF and break through to wash primer level is it alright to cover with SPI epoxy?
 
in that case finish with the ppg on this job.. next job... do spi but on baremetal only.
 
Its fine, the SPI epoxy won't do anything to the acid etch that the ppg LF won't do.

We just warn against it, for best long term results.
 
yes, in regards to epoxy over acid etch primer, its really not brand specific so putting dplf over etch is no different than putting spi over it. both will work just fine over it, just not the best way to do it. you kinda lose some of the advantages of using epoxy this way. basically a paint job is only as strong as its weakest layer.
 
Oh geeze don't get me started with putting things over wash primer. Customer just did this on a 100k + car..
car is completed and easily a show winner, but now time to strip and re-paint.
 
Is the last reply a joke, I don't understand? I am trying to find out if this SPI epoxy will work if it (and it most likely will) comes in contact with the wash primer after after sanding. If it isn't a good idea than I will continue on with PPG as it was recommended to use wash primer under it (DX1791).
Thanks!
 
It's not the epoxy that would cause the problem, it's the wash primer. But epoxy would be the best thing to put over the wash primer IMO.

But no, not a joke they do have to completely strip a car down and re-do it. After seeing that I see no reason to gamble, if i had a car that was in wash primer i would personally stip it off and start over. not worth the chance.
 
what i would do is scuff up the ppg epoxy good and apply 2 coats of the spi epoxy then start doing your sanding and filling on top of that. Gives you a good barrier over the washprimer. You still might cut down to it in a few spot but will be considerably less. Whatever you do, dont apply any filler to any of the exposed ares of wash primer.
 
The pieces that have wash primer already have all body work complete and covered in PPG epoxy. In some places the PPG epoxy was sprayed thin and this is why I want to scuff/sand and re-epoxy. It sounds like the SPI will work.

Chad, what problem did the other car have with wash primer?
 
Did you do any filler work at all over the wash primer or was the filler done on bare metal then wash primer and epoxy over?
 
Filler work was done on bare metal. Wash primer was applied after the filler work but not over it.
 
portland;4163 said:
The pieces that have wash primer already have all body work complete and covered in PPG epoxy. In some places the PPG epoxy was sprayed thin and this is why I want to scuff/sand and re-epoxy. It sounds like the SPI will work.

Chad, what problem did the other car have with wash primer?
Click to expand...

The whole car is bubbling, it's all over it, the wash primer has lost it's adhesion. Light surface rust underneath all the areas that we sanded through to see where the root of the problem was.
 
We the wash did not loose its adhesion, what happened, is the 2K type primer melted the wash and wash breaths and holds air and now has solvents mixed in from being re-flowed or melted.
As the air and solvent set on the bare metal, it starts to rust and that is what causes the little bubbles, pinheads to form from the gassing caused by the rust.

Its just a damn shame, the guy used it on that car but I'm sure he had plenty of reasons to not listen to people as to why he should use epoxy.
 
I'm doing a Camaro that has wash primer and 2K urethane primer on it, we are simply DAing the primer off and putting epoxy over the bare metal and existing filler. Since the bodywork was pretty wavy anyway, and needed some rework, it's no big loss that the filler got DAed a bit. We are skimming it all with poly putty over the epoxy.

I would suggest the same thing for the OP.
 
I am going to scuff/sand and re-coat with epoxy either PPG or the SPI that I bought. The way I look at it if the epoxy dries and locks down than anything over it isn't going through to the wash primer. I think it will be fine.
 
PPG's DPLF is a poor solvent barrier-you can wash it off with lacquer thinner even years later. Once you get some SPI epoxy on there you'll then have a good solvent barrier.
 
I think we are on the same page, use the SPI and it will have a good solvent barrier which will prevent the topcoats from attaching the wash primer.
 
if you mention this on the tri5 site you will get mobbed by ppg lovers who swear it wont wash off.
 
I have to agree with brad, but each project has it's own purpose and nobody here can answer that for him..
I've had some beat up mustangs i threw some paint on over the years just to freshen them up some. I didn't care so much what they looked like at the time as long as they were one color.. If the paint started bubbling here and there on one of those i could have cared less. but I was 18 at the time and wouldn't have striped one down to paint at that time.
 
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