RE: Sealer for fabric
PolyC is not glow fuel proof. Even 0% nitro methanol-based fuel will cause it to soften. Nelson's Clear worked great as a fuel-proofer over PolyC when used with the cross-linker but sadly, Jerry has had to close up shop. I went to System Three's website (what Nelson's was based on) and low and behold you can get the Clear gloss and satin from them. It even comes in small quantities (4 oz.) for a fairly reasonable price. Use the cross-linker that goes with it for a fuel proof (at least 15%) finish.
BTW, I use the cross-linker even when I don't need the fuel-proofiness like on electrics because the finish is harder and more durable after curing.
Curt