acrylic over 2pac

[coupe]

Hi guys I'm getting ready to rebuild my ej pano and just thought I'd ask the question for the paint gurus. Heres what I usually do but would like some advice before colour. After bare metal I use a dupont epoxy primer(urethane). I then smooth out with body filler over any minor dents. I then use dupont 2k primer filler, smooth out etc. What I would like to know is can I paint acrylic over the 2k primer. The paint tech says yes but acrylic uses thinner to 'bite' into the undercoat and I've found that the thinners wont penetrate the 2k. Do I need to use an acrylic primer over the 2k primer to help adhesion of the colour top coat?

[rosco]

I can't answer your question with any confidence as I haven't done this, but if I were to attempt the job - I'd make sure I keyed into the 2K for any acrylic coat to get a grip on.
I'm not sure that there would be any difference in the top coat bonding to the 2k than acrylic primer - but I would apply acrylic primer under acrylic top coat for my own peace of mind - makes sense to me to use both.

I am almost certain I have recently read somewhere in this forum where someone applied acrylic top coat over a 2K primer - but can't remember.
And yes, once cured - I'm pretty confident acrylic thinners has no purchase on 2K by fusing into previous layers - a hefty keying with wet and dry is probably your best advice.

frats,
Rosco

[coupe]

Thanks Rosco, kinda what I was thinking too

[wot179]

I would be referring to the technical data sheet.

[coupe]

Both the paint rep and the data sheet say its all good to spray acrylic over the 2 pac. I have tried this and have noticed that once you get a small chip that the paint is easily removed from the area. Is this just an acrylic thing? I was hoping someone had experimented a little with this and was wondering if spraying acrylic undercoat first would make any difference

[Trev]

I have my EK sedan painted with 2pac completely and when you get a chip it can and dose chip away pretty easily .
I have painted a pair of spats and a set of wheels using 2pac primer and acrylic top coat and clear 2pac and it has worked well as far as chips are concerned (can't say they are expert quality painted, seeing as I did them myself ) .
I would say have a go on a test panel and see if your happy with the outcome, Trev.

[bootlegger]

Hi guys I'm getting ready to rebuild my ej pano and just thought I'd ask the question for the paint gurus. Heres what I usually do but would like some advice before colour. After bare metal I use a dupont epoxy primer(urethane). I then smooth out with body filler over any minor dents. I then use dupont 2k primer filler, smooth out etc. What I would like to know is can I paint acrylic over the 2k primer. The paint tech says yes but acrylic uses thinner to 'bite' into the undercoat and I've found that the thinners wont penetrate the 2k. Do I need to use an acrylic primer over the 2k primer to help adhesion of the colour top coat?

All the acrylic jbs i have done are with two pac primers.
Once i have got them right i always coat with acrylic primer. Rub back with 600 then paint.
So far so good..
Ive had people tell me i can paint straight over two pac primer also.
Not game enough to try it out on a customers car and then have delamination problems.

[rosco]

Coupe,
with paint chips, my experience has been that it is the weakest grip on the substrate which lets go.
Generally, etch primer applied well will hold out and stay intact to the metal/filler.

It might just be me, but I have yet to find properly applied acrylic primer doesn't stay fused to the top coat - resulting in the chip breaking bond to the surface at the etch primer or base metal/filler.

I made some huge mistakes earlier in my attempts to spray - and for a short time blocked back the acrylic primer working down to 1200, believing I'd get a mirror finish (false!).
End result was any knock flaking off the top coat and leaving the primer exposed.

I have not ever sprayed 2K due to iso-cyanate concerns - and have zip experience/knowledge in them. I would hope that a 2K primer would bond to the substrate to the same extent as a 1K etch, but can't comment.

I would again suggest for over-coating acrylic over 2K, that the 2K be keyed with at least 600, but I would prefer 400 - then acrylic primer applied and the normal 600 blocking down for the top coat/s.

Just what would let go with a stone chip after that is beyond my experience.

frats,
Rosco

[coupe]

Thanks for all the help guys. I spoke to the paint rep today and he said no probs with painting acrylic over 2 pac primer. This is what he said. Sand the 2k primer the day I paint with between 320 and 400 grit. He said 2k primer has a tendency to "heal" itself for lack of a better word. He said that the sand marks would tend to close up over the period of a day and you need this for the grip of the acrylic to the 2k primer

[rosco]

Thanks, Coupe

I would still suggest you consider spraying a couple of coats of acrylic primer onto the 2k.
As you probably already know, the acrylic top coat will follow the contour of what it is applied to. Using 320 or 400 to key up the 2K primer will leave fairly deep cuts in the base. I believe this will show through as the acrylic top coat flattens down. By applying acrylic primer between the two, the 600 will prevent this happening to your acrylic top coat.

frats,
Rosco

[coupe]

Thanks for all the help Rosco, I think I'll give that a go, I'll let you know how I go

[Nekro63]

Yep, nice thin coat of acrylic primer in a 'wet on wet' method. So when the 2k primer is all rubbed cleaned and masked, spray your thin acrylic primer, flash off/dry then acrylic paint straight after.

Also with paint chips in basecoat jobs, you can mix your basecoat 8:1 with hardener and it should be alot better.

[coupe]

Maybe a silly question but do I sand the acrylic primer before acrylic top coat or just paint straight over while the acrylic primer is still soft/fresh?

[rosco]

I haven't used the method Neckro mentions, I have always preferred to do things "long hand" - I know that method, and am comfortable with it.
Guess it's my preference to "work" how I do things - I'm in no hurry, and enjoy the procedure.

frats,
Rosco

[Nekro63]

Maybe a silly question but do I sand the acrylic primer before acrylic top coat or just paint straight over while the acrylic primer is still soft/fresh?

No just paint over it and should bite in no worries. Similar method is used with 2k products like PPG's dp40 primer