G'day

After been fibreglassing for a while now repairing various bits of broken body kits on mates (ricer) cars, making door pods and doors trims, parcel shelfs and fixing cracked boats. I thought i knew a fair bit about fibreglass and what it will and wont do. Until i tried to make my gauge pod for my tacho and air/fuel ratio.

I started by sanding down my dash facia in my xf, making sure to remove all the plastics knobs and any greasy patches. I then cleaned the facia with wax and grease remover.
I did the usual procedure for making a pod. Make the frames, temp gluing to the item i want to fibreglass to and then throughly clean everything. I stretched the material over the pod and to the dash facia. I did the first coat of resin, no worries, did the second, no worries.
So after sanding the fibreglass down it was time for the bog to go to smooth the lot over. Put on, let it go off, sand it smooth. Done, time to paint. I put a coat of plastic primer on the rest of the exposed plastic first. Then i applied the grey primer, that where the trouble started. As the primer dried the fibreglass and bog lifted off the plastic, .
Thinking it was just grease and sanded those areas right off and applied more plastic primer and then primer. As soon as the primer hit it lifted off again.

How do you get it to stick to the plastic?

Cheers

try applying the resin to the bare plastic without any plastic primer....

Resin was straight to the plastic, the primer was put onto the rest of the exposed plastic. The rest is fine just where the edges of the fibrglass are.

Cheers

Roughen up the plastic to give it soemthing to stick to?

G'day

Tried that too, when i sanded it back after the first go witht he primer i scratched it up with a wire wheel. It just pulled out of the scratches.

Cheers

are you using plastic primer? There is a different type of primer for plastic, not sure that this is what is causing your problem though

G'day

The only thing i can think of that i haven't tried is to spray the plastic primer and then fibreglass over that!

The primer is the special plastic interior primer.

Cheers

sounds like you may be getting a reaction between an enamal paint and an acryllic paint. enamal paint will stick to anything but acryllic and 2pak wont. or similar effect the primer is reacting to the fibre glass in the same way. had this problem on a boat before.

G'day

That could be the issue, but. The paint i'm using is still automotive paint so i'm not sure.

It looks like it gets air under the bog and when you apply the primer it makes the air expand. As the primer dries the bubble goes down and then eventually opens up as a crack.

I'm a little confused, so i'll just try a few things and see what happens.

Cheers