Hi,

I'm newly registered user but have been reading around autobody101 and other autobody websites for a while concerning this subject and others.

I have a coat of cured PPG DPLV epoxy primer on my car that was applied DTM and I've sanded down. Now I want to apply more DPLV epoxy primer and then spray Evercoat Featherfill G2 over that within the epoxy recoat window. My plan is to do my final filler work over the Featherfill. I'm doing filler work over the Featherfill because I tried doing it over the epoxy and it was turning into an endless cycle of applying filler, sanding filler, spot priming sand throughs, applying more filler, more sand throughs, and more spot priming. I'm trying to avoid sand throughs and spot priming.

My question is this:

PPG technicians say I can apply a polyester primer over the DPLV without scuffing (or optional scuffing) after a 24 hour dry on the DPLV.

Evercoat technicians say I should wait at least 72 hours after applying the DPLV before applying the Featherfill to allow the epoxy to fully out-gas, otherwise the Featherfill may bubble. Evercoat techs also say that I must scuff the DPLV before applying Featherfill.

Should I be conservative and wait the 72 hours and definitely scuff the DP epoxy with red scotchbrite before applying the Evercoat Featherfill G2?

Or can I be confident that the Featherfill will properly bond to and not adversely affect or be affected by the epoxy if applied after 24 hours?

Thanks,

I'm going to go ahead and post these pictures while I'm lurking here:

I performed a test over the last 48 hours to see how spraying the Featherfill 24 hours after the DPLV would work out.

I prepped a piece of sheet metal with 80 grit paper and wax and grease remover.

I spray two coats of PPG DPLV 2.1 Epoxy Primer over the entire panel and let it cure for 24 hours. I then scuffed half the panel with a maroon scotch brite and didn't touch the other side. I used wax and grease remover again.

I then sprayed two coats of Evercoat Featherfill G2 and let dry for about 15 hours before starting my adhesion test. Here are the results of my test:

I first scratched a crosshatch pattern (kind of like what's described here https://en.wikipedia.org/wiki/Paint_adhesion_testing) with a razor and applied tape over this and pulled the tape off to test the adhesion of the G2 to the DPLV. Some of it came off but not a lot.



I then started sanding through the G2 until I hit the epoxy. The G2 sanded smoothly and featheredged and did not flake off. It did seem soft.

I then scraped on the epoxy with my fingernail and the epoxy was quite soft.



If I let the epoxy air dry for a few more hours it became harder and I could barely dig my fingernail into it.



I sanded the rest of the way through the epoxy to bare metal and it did featheredge okay.



I think the MEKP or the acetone I added to the G2 was softening the epoxy or trapping the epoxy's solvents not allowing it to dry. It does seem like one should wait longer before applying the G2. Perhaps the epoxy would eventually dry, but who knows.

The scuffing with scotchbrite didn't make a noticeable difference. Not a great test but I just wanted a rough idea.

tech sheet says one hour to top coat, i would wait the 1 hour to G2 not 24 hours

PainterDave wrote:tech sheet says one hour to top coat, i would wait the 1 hour to G2 not 24 hours

That's a good point.

PPG's conflicting information came from their polyester primer (VP2100) tech sheet "For optimal performance over bare metal, apply VP2100 over VP2050 DTM High Build Primer, DPLF Epoxy Primers or DPLV 2.1 Epoxy Primers after an overnight dry and light sanding. Note: Do not apply VP2100 over etch primers." I assumed their polyester was similar to G2.

And then when I called their tech line they said wait 24 hours.

well.... the acids in etch and the glue in epoxy dont like eachother.

so do not use both

I'm not using etch. The point I was trying to make is this:

The PPG VP2100 Polyester Primer tech sheet says:

"Apply VP2100 over DPLV 2.1 Epoxy Primers after an overnight dry and light sanding."

As opposed to the DPLV tech sheet which says:

"to topcoat: 60 minutes at 70F"

As opposed to Evercoat who says:

"Wait 72 hours before applying Featherfill G2 and scuff or sand the epoxy"

i use different products.

i use Valspar CPS Epoxy and i use feastherfill G2, i wait about 30 minutes after epoxy to G2

i dont see anywhere G2 says to wait over epoxy,