Applying carbon fiber veil without dope

[Mike Griffin]

Has anyone found a way to apply and fill carbon fiber veil over solid balsa surfaces without using dope?

Thank you
Mike

[Gerald Arana]

Hi Mike,

That'd be like building an airplane "without" glue wouldn't it? 

Guess it could be done...........

Jerry

[Mike Griffin]

Hi Jerry, yeah I guess it would.  I am just trying to eliminate using dope as much as possible.  I was thinking about maybe trying to put it down with Polycrylic or maybe polyurethane to see if it would work.  Just wanted to see if anyone else had experimented with alternate methods. 

Mike

[Serge_Krauss]

I've used epoxy and gotten a fairly light strata. My .56 oz fiberglass/epoxy layers have been lighter, because they seem to absorb less epoxy. I built a couple very light profile fuselages that way - around .6 oz for an LA-.25 stunter fuselage.

[MikeyPratt]

Hi Mike,
To make a long story short, no it's to easy with dope.  I've used finishing resin before but it smell worse than dope.  Also, if you are trying to not use dope at all, then use finishing epoxy brushed on the surface then wipe off as much epoxy as you can.  Then place C/M on the surface and smooth out the Matt.  When dry, brush on a coat of clear Superpoxey clear (or the equivalent) and let dry.  Sand with 220 grit sandpaper which gives you a wonderful surface to start the painting.

Another option is to use Superpoxy clear on the surface, add .5 glass cloth, place a layer of cling wrap over the glass and squeeze out the excess epoxy and allow to cure (2 days).  I've used this method many times on racing models, team race, goodyear, rats, fuse, flaps and elevators on stunt models.  You will find this method leaves a glass smooth shiny surface.  Standoff the shine with 360 grit sandpaper prime & paint from there.  This does take a little skill to get it perfect but I nailed it the first time and have used this method many times.

Later,
Mikey

[Motorman]

I've brushed polycrylic over polyspan but you should use 2 coats of 50/50 nitrate dope first so it doesn't raise the wood which smells just as bad as using all dope to apply cloth. Also, the polyspan absorbed so much polycrylic that it was heavy, very strong though but not something I would recommend. If I do it again I'll try to brush the polycrylic on real wet and lay the cloth over it real quick. For now I just use Sig nitrate dope.

What I did is get an organic vapor respirator from home depot and now I can dope for hours smell free. Of course that doesn't help if you're painting in your living space.

MM 

[Fredvon4]

Mike on my smaller 1/2a stuff I use the thin light CF over bare balsa using Elmer white glue thinned with water

one side at a time thick  70/30 Elmers on the balsa, lay one CF, thinned 50/50 in the veil, cover with Saran, lay PLY, glass, ot other flat no texture on top and weigh down over night then other side

I don't bother with thin top and bottom cuz usually sanding cuts the edges and there is now no point to the CF on the thin section

[Serge_Krauss]

Mikey's certainly right about glass/dope finishing. The dope allows the glass to take almost any reasonable contour without difficulty or mess. In that method, I dope the balsa three or more times and sand, if necessary. Then I drape the cloth over the fuselage and apply thinner through the weave. This pretty much attaches the glass flawlessly against all compound curves at the wood surface. My problem with this technique was that it required too much dope to fill the weave. I believe that this was because successive coats, although brushed over the completely dry surface, floated the FG cloth.

That's why I went to epoxy. The obvious problem was the gloppy mess! This was regardless of my having squeegied the first epoxy coat to a very thin, barely-visible sheen and laid the cloth over it, rolling it under waxed paper with a roller to squeeze out all the excess. Even though I waited for it to tack before filling the weave (to prevent floating), the stuff was a real pain. If I had a vacuum-bag set up, it would work much better. So there was messy labor involved, with less compliance to my compound curved surfaces. I applied the second (weave filling) before the first was entirely set so that it would adhere the best, and I wouldn't have to sand off the waxy surface residue until all had set up. Nonetheless, the epoxied fuselages were lighter than the doped ones. Just use gloves, great patience, and expect set-backs as you work the fabric the first time you try epoxy.