It is my understanding that carbon veil was developed in the aerospace industry as a laminate between separate sheets of material. In that capacity, the veil works very well. Like try it between two sheets of 1/32 or 1/16 balsa, cross grain and you will get an excellent base to cut fuselage formers with lots of cutouts and will be very light. Or you can laminate balsa shells with this stuff between the two shells.
What I think we have observed with these model airplanes is that the carbon veil is usefull in the coating of sheet or otherwise all balsa surfaces. Maybe not its intended use, but works on our stunt models.
Overall, I have found that the surfaces are more resistant to dings and dents than with silkspan or even silk, but what I like about the veil is that it does two things for the surface. With the nitrate base and brushing on with nitrate, the surface has a nice hard "eggshell" quality, more so than with silkspan and butyrate dope which is more "plastic" to the touch. Also, for sheeted surfaces like the flaps, there is a noticeable "stiffness" both in torsion and chordwise flex. I cannot quantify this with numbers but definitely can tell the difference after application of this stuff. The other benefit is that the veil does a better job of filling in the grain of the wood, using less filler to fill the grain and for hiding the grain better as the model ages where silkspan covering will sometimes allow the finish to sink in or otherwise tend to expose the grain more.
Now, what my experience with the carbon veil is to use over wood sheet and to lay over various components like cowls and wheel pants. And what I write here is comparing using carbon veil to silk and silkspan. I seal the wood surfaces with clear nitrate, about 3 or 4 coats thinned enough to brush on easily and sanded lightly to get rid of the fuzz. Then brush nitrate through the veil much like you would with silk or silkspan. When the nitrate hits the veil, it will have a tendency to separate if you keep pulling/brushing over one spot, so avoid doing that. It will almost self form over compound curves much more easily than silkspan, but you will find how much you can "pull" the material before it starts leaving gaps. There will be places that there will be overlaps. You will want to minimize the width of the edges of those overlaps. I then brush on about 3 coats of thinned nitrate. At this stage, the veil acts like a sponge. You will need to brush on enough clear so that you can start sanding to get rid of the fuzz and surface irregularities that have shown up in the veil. If you do not have enough clear on it yet, the sandpaper will just pull the veil from the surface This will take like 220 paper, dry, and the veil really chews up your sandpaper. It might take 3 or 4 or even more coats of clear and and wet sanding again with 220 paper, but you will start getting a really nice as a base for the rest of the finish. At this stage, you can tell how much you are sanding. When you actually sand enough until you are really getting into the veil material itself, it will start changing shades of black to grey. The overlaps can be sanded until all of the overlap is eliminated as it will first show dark black where the overlap is, then with sanding, you can see the overlapping material being removed. With proper sanding, you have not added that much weight through the whole doping/covering process and you have a nice hard base to start the real finishing. At this stage, you can sand with 320 and 400 paper, wet, and start getting an almost polished surface. However, there will still be voids and pin hole pits in the surface. You are then up to your own method of filling/sealing to get ready for color. I have used Sig and Brodak fillercoats for this. The Brodak does OK. Brush on a heavy coat, sand it away and you will see where all of the voids are being filled in. Brush on another thin coat of filler coat sand carefully, because the sandpaper will want to drag the fillercoat out of those voids. Then, a coat of fairly thin clear, sprayed on will seal the fillercoat and you have a good base for color.
Or you can use an epoxy primer after the nitrate coats are finished and you will have a really great base for your color, though there will be a weight penalty unless you are very carefull and thorough on how well you sand the primer. Again, the carbon veil gives some very good visual cues on how much more sanding is or is not needed.
I primarily use the 0.2 oz material. The 0.5 oz stuff ends up a lot heavier because it takes a lot more clear to fill it, or a lot more work to get it sanded lighter. However, if you want to have some flaps that are practically indestructible and have little flex, cover them with the 0.5 oz veil and epoxy. They will be really stiff but weight can be a real problem. That carbon veil and epoxy is something that does not sand very easily to get ready for any finish coats.
There are probably a myriad of ways to work with this stuff. I do not claim this is the best, but it works for me.
Keith
Topic: Carbon Fiber Veil vs Silkspan vs Polyspan (Read 3476 times)