Temporary finish coat on fiberglass?

[Thermos]

Hey all,

I'm starting finish work on my spinner, it's the first piece of fiberglass on which I've done any pinhole filling and painting.

I've seen a lot of pictures of RVs with gray paint, maybe primer, on the cowl and other fiberglass parts. What have you used as a temporary finish coat on your fiberglass? How do you know what's compatible with future topcoats?

Thanks,

Dave

[6 Gun]

On fiberglass most use epoxy gray primer and you can get it in white or black also.
Now a question for you how does the Thermos know if its hot or cold?
JK
Bob

[lr172]

For the most part, compatability is no issue. Most primers that your painter will use will stick to anything but certain plastics and silicone. Whatever you put on will be sanded and the new primer will adhere with mechanical adhesion. There is no cross linking with cured paints.

No matter what you put on, your painter will want to put on another primer coat, so keep your coat thin. Many will not paint it without completely removing what you put on it and charge you for the effort. Most painters won't warranty a paint job unless they did all of the work from the base material up.

It is generally a bad idea to apply a porous primer (typical 2K build primers) that is expected to reside in the elements. It will absorb various bad things from the atmosphere that can be hard remove and create potential contamination that will impact adhesion. Best to stick with an epoxy primer that is not porous.

Larry

[Carl Froehlich]

On the RV-8A I flew it for two years before the final paint job. For all the fiberglass parts and after the filling and sanding I did PPG primer with one coat of single stage PPG paint. Painting was all done in the garage - no special booth or such. The rest of the plane was bare aluminum.

This looked amazingly good for being so easy. Final paint was a good wet sand of the painted parts, a light coat of PPG primer, then PPG base and clear coat.

Carl

[Ralph Inkster]

My painter suggested a urathane primer, would seal & is relative easy for him to knock down before when he applies his final primer coats. He strongly stated he would not be happy if any rattle can primer was used on the glass pieces as he would have to remove all traces of it before proceeding with his primer/paints.

[Thermos]

Thanks everyone for your help. With your assistance and some re-reading of Dan Horton's posts, I think I have a handle on prepping my fiberglass parts.

Originally Posted by 6 Gun

Now a question for you how does the Thermos know if its hot or cold?

Bob, the Thermos (AKA me, that was my USAF callsign) has lots of natural insulation - except on the top of my head - and doesn't notice the heat or cold that much!

Dave