I’ve painted alot of fiberglass sailplane fuselages. I can appreciate what you went through.

The first thing I do to a fuselage is to remove the mold release with a strong solvent. Acetone will definetly de-wax/de-grease the surface (wear gloves and do it outside!). I don’t think hot water and soap is strong enough to remove the mold release. If you do not have all the mold release removed and you sand the surface, you will “grind” the mold release into the surface pores. After the acetone wash, I wet sand the surface with 220 wet/dry. Next, I use an auto body “glazing” filler to fill the pinholes. It dries in 30 minutes and is very easy to wet sand. Epoxy and microballons is much harder to sand. You’re now ready to prime.

When applying primer, if you see more pinholes try simply rubbing the wet primer into the surface with your finger. The primer coat is not supposed to be pretty, it’s for smoothing and filling the surface. If you found you missed something bigger than a pinhole, use the glazing filler again. You’ll probably need at least 2-3 prime coats.

Right before applying your color coats, wipe the surface with rubbing alcohol and avoid touching with your hands. Your hands contain oils that can cause the paint to fisheye.

These techniques have worked quite well for me.