PPG epoxy failing
 

I am a hot rod shop out of GA and have used PPG for over 30 years with no real problems till lately. The DP epoxy line that we have all used forever is failing me, before the LF or lead free label hit the can it would stick to plate glass around probably around 1998 after that it had to have more cure time before top coat which as of late is at least 24 hrs. But now even at that will pull loose from sandblasted metal, bondo, plastics and sanded metal. I'm even seeing cars at shows where this seems to be a problem any one else experience this as well ???

I have not encountered this problem and use the product regularly.

What product are you putting on top We use K36 and have for over 10 years with no problems until last 3 years it pulls without even topcoat even when wet sanded an let sit for a week standard 3 coats primer !

In my early years... the '60s... I used DuPont. By the '80s it was failing on me.

Then I went PPG until about 2010. After about 2005 I started having multiple failures due to new formulations, which they NEVER TOLD ME ABOUT! Today I only use their production color basecoats.

Now I am using a mix of those base colors, plus...
House of Kolor and Xotic Colours custom mixes...
HOK SG100 midcoat clear...
SPI epoxy primer (also used as a sealer)...
Marhyde Ultimate 2K primer...
and SPI Universal Clear.

For reducers I use SPI for the good stuff, a couple generic brands for primer and such.

These all work wonderfully together.

As far as using one paint system only... I have never had long term reliable results that are as good as what I am using today!

Now I can't make this clear enough, I am not saying it's impossible. I am also not saying that the product could be way to temperamental where a tiny little thing can make it fail that another product wouldn't be affected by the same "mistake."

That being said, as a painter for 20 years at the time I became a paint rep which I did for 4 years in the late ninties, I never saw a product fail like that where there was anything wrong with the product, it was the application.

Now I say that because on a regular basis I was attending to failures where the customer blamed it on the product. It is so common it's crazy to hear terms like "bad batch" and stuff like that. I researched these failures over and over and over, saw everything you can think of and a few that would blow you away they were so damn stupid.

So if you really want to FIX the problem and not simply throw blame, study what you did, study the substrate , study the temp solvent and or catylist used. Study the application, the amount of coats of the primer and the substrate, how much overlap, ANYTHING that can affect the solvent that stays in the film, solvent entrapment is without a doubt the number 1 reason for failure, hands down.

Just some ideas as I know nothing about those products in particular.

Brian

We put Omni MP243 polyester primer over it usually. After sanding and filler. I used the K36 over it five years ago and theres been no problem on that one.

Start using SPI epoxy I turned a PPG rep to it and even he cant believe how much better it is than the DP.
I stopped using the DP epoxy when they made the change but even when DP-40 was the best it was rough sanding it,it was just the way it was and we accepted it. SPI epoxy sands fairly ez, not quite as ez as a 2k filling primer but ez enough. you can also build with it if you want just spray more coats but usually 2-3 coats is all that's needed. Most of the work I do is epoxy only, no 2k or any other primers. There are times when I need a quick drying 2k and when I need one SPI has an excellent one at a fair price its called standard 2k primer It'll be sandable in 3 hrs and ready to paint. ( I've done it so its true) Back to the epoxy, it can also be reduced to use as a paint sealer or lets say you sanded a new hood and theres a lot of metal showing,You can reduce SPI up to 40% if you want and spray that hood then turn around and paint it a few minutes later. Its the best epoxy I've ever used and I use a lot of it.
The only problem I've ever had was spraying it below 55 degrees but that was my fault ,I knew better but did it anyways, Even then, It just took a week to cure and it was fine. My shops in Augusta,Ga.

How was the metal prepped?

True enough...But still, Dp epoxy is just plain junk. get rid of it. Just like some cheap primers shrink, its just how they are, stop using them.

In defense of the LF Epoxy.
Two things to get advice from your PPG rep.

First; how you are cleaning the bare metal, went to any “off the wall miracle cleaners” lately that have an acid, or cleaning with lacquer thinner or pure acetone? All the above can cause your problem that you are having.

Second and what I believe is your problem but check with PPG as all epoxies are made different.
We recommend the epoxy set for 48 hours before spraying a polyester type primer so the epoxy can get further into the curing process, as the acetone and thickness of the polyester primers can cause a melting type action aka wicking, where the urethane primer will not so we can primer sooner.

Example without writing a book, so you understand.
Acetone is very aggressive but if you wipe the hood of your new car with it, it won’t hurt a thing.
Now wet a rag with it and set it on the hood for ten minutes or so and it will look like paint stripper was applied.

Some points to discuss with the factory rep.

I do remember when it changed to "LF" and it was a BIG difference.

Brian

I don't use urethane primers very much so when I did I just ran down and got a quick qt of omini 2k it seemed like pretty good stuff to me, that is until I saw how bad it shrank on a black truck I did. It looked great for a while, only it seems to shrink for months but very slowly, after a year or two its pretty noticeable.(if that makes any sense). I had to toss the omini 2k primer and chalk up another one as junk not to buy. I should have known better but my guy that delivers my materials doesn't have qts just gallons of primer and about a qt got wasted because it was just too thick to use after a while. Now I take the time to clean the top of the can and seal the primer up well so it lasts longer.

It doesn't seem to matter 110 grit dry 180 grit as of lately sand blasted on a set of rims, PPG rep out Monday would not address blame just that they would take care of it. wanting me to swap to wash prime DPS3055 and DAS3027 the prime alone list over 400 with hardener Prices are getting out of hand.

Thanks for the reply's to this issue I would not be so much aggravated if it was a new product or had some changed conditions. the metal was sand blasted but have tried 100 grit as well . I'm seeing that you have to let sit 3 days to guarantee adhesion "don't have that long all the time" it is my belief that the DP doesn't dry like it used to and the K36 Dries so much faster and harder with a lot of shrink rate probably as much as 20% using mix cup test and just pulls it out of gaps.

The prices these guys want infuriate me especially when they don't preform well. That's the main reason I do what I can to inform everyone that theres a better product out there and at a cheaper price. One of the things I love about SPI epoxy is the cost, at around 150- 200 for the primer and hardener (2 gallons) its a good deal and its top shelf stuff. Id call SPI and see who sells it near you or order some if you have to. You wont regret switching, you'll actually feel good about it. Its a good feeling knowing you can stick some 2" tape anywhere you want and yank it off without pulling of all the paint and primer with it.