How do you paint a fiberglass over foam wing?

I bought a Wizard E from you at Toledo this year and I am finally getting around to finishing it (just in time for winter). I'm wondering what to use to paint the flying surfaces. I tried Krylon and Createx and they both peeled right off. I asked the gang on RCSE and one guy suggested felt pens (though he said it didn't look very good) and Jim Bonk suggested sanding the surface with 600 and then using rubbing compound before painting. I tried that but the Createx still peeled right off. I used 21st Century on the fuse and canopy, so I know it sticks, but I'd be afraid of dissolving the underlying foam. Any suggestions? I know I should just leave it as-is for the lightest weight, but I'd really like to jazz it up a little.

From : Joe Hahn

Hello Mike.

Good question!! I've never painted one of our bagged wings/tails, so I can't answer from personal experience. The concept of microscopically "roughing up" the surface with a very fine abrasive so as to remove the gloss sounds like a great start. We do wax the mylars from which the surfaces are made and it is likely that some of that wax remains on the surface, which would have to be removed prior to painting.

Thinking about this, the first step would be to use a mild solvent such as alcohol. Check it on a piece of scrap styrofoam to be sure it will not attack the foam. Lightly moisten a cloth with it, then gently rub the surface to remove any wax residue that may be present. Roughing the surface up first may actually grind the wax down into the surface, not a good thing. NOW use very fine abrasive paper, or PREFERABLY a "scotchbrite" abrasive pad(it is a little like steel wool, but not made of steel--hardware stores typically have it) gently rub it over the surfaces to remove the gloss.

This should allow the surface to be painted. I've found that VERY, VERY LIGHT coats of paint, allowed to dry between coats, is important to produce a decent finish without runs AND without attacking foam. The first coats should be a very light "dusting" at arms length, with very spotty, ugly results. You do not want a build up of paint on any spot any time during application, just a fairly uniform pattern of paint "dots". Many coats of this type will eventually result in a uniform coating, just be patient in allowing each coat to dry to touch before applying the next coat, and don't try for a complete, uniform coat on any one coat. The ugliness will eventually turn into a nice looking finish!

One other note----you will probably find a fair number of pinholes in the surfaces. This is because we do not use gelcoats(HEAVY!!) on the flying surfaces. In fact, we squeegee the surfaces thoroughly to remove all excess resin when we bag, again to save weight. Pinholes are a side efect of this. They can be filled with lightweight filers such as "Model Magic", etc., but again that will add more weight. Just depends on how much the appearance means to the individual, and how willing they are to lose some performance in trade for the appearance. Light airplanes do fly better!!

Hope this helps. I'll forward your question to Don for possible comment also.

Thanks for the inquiry Mike!! Good luck with your Wizard E!!!

Joe Hahn
DJ Aerotech