Preparing RV-12 Fiberglass for Paint

[Tacco]

Getting ready to paint. The fiberglass parts I have are the newer version that appear to be primed already. Doesn't look like Gelcoat. They are of pretty good quality, only a few pin holes plus the imperfections I induced during trimming and fitting. My inclination is to just hit the imperfections and low spots with rattle can high build primer (SEM) and sand the whole part with 320 then shoot PPG epoxy primer. Seem reasonable?

[Kyle Boatright]

My recipe:

Scuff first.

Fill pinholes and imperfections.

Sand.

Prime.

Paint.

[rongawer]

Depending on the size of your pinholes and imperfections, you might try a little peanut butter epoxy with microballoon mixture; it?s the ?aviator?s bondo? and works very well. Then sand smooth, prime and paint.

[D&M Dan]

A good trick we use is spray with high build primer then before block sanding, spray a rattle can light coat of guide coat on the piece. It will show any and all imperfections as the guide coat will lay in pin holes and problem areas as you sand.

[snopercod]

Kyle had an excellent list but I would make the first step, "Clean the workpiece with Prep-Sol wax and silicone remover". You want to do that before any scuffing or sanding so contaminants don't get worked into the surface. Rather, you want them to get dissolved and carried away by the solvent. The proper way to clean with Prep-Sol is to wipe the workpiece down with a very wet rag then, immediately remove it with a clean rag. I do it with one rag in each hand. If you let the Prep-Sol dry on the workpiece, the contaminants will still be there.

The pinholes will drive you nuts. You can think you filled them all in but, after you sand and primer again, more will appear. Don't get discouraged - that's just how it goes. The high-build primer will fill some of the pinholes, but others just get "bridged" and will reappear when you sand. Some people use a small roller or a squeegee to apply the high-build primer to drive it into the pinholes.

I have used Evercoat polyester glazing compound and a razor blade with good success on pinholes.

[Tacco]

Thanks guys. How about the fiberglass canopy fairing where it transitions to Plexiglas. I'm concerned that the solvents in the paint will damage the canopy. My inclination is to mask it so that the paint overlaps the fiberglass a tiny bit onto the plexiglass. Anyone have any problems in this area?

[snopercod]

Originally Posted by Tacco

My inclination is to mask it so that the paint overlaps the fiberglass a tiny bit onto the plexiglass.

That's exactly right. When I did mine, I used black electrical tape to mask off the edge of the plexiglass. It's very flexible and worked fine. In my case, I went through that process several times. I'd add micro filler, sand, then remove the masking and move it back 1/16" for more filling with Evercoat and eventually paint.

[rvbuilder2002]

Originally Posted by Tacco

Thanks guys. How about the fiberglass canopy fairing where it transitions to Plexiglas. I'm concerned that the solvents in the paint will damage the canopy. My inclination is to mask it so that the paint overlaps the fiberglass a tiny bit onto the plexiglass. Anyone have any problems in this area?

I have never seen any issues caused by paint being applied directly to a canopy.

Some people have purposely painted portions of their canopy for a permanent sun shade.