RE: Sealer for fabric
I don't think the Behr clear is available anymore. I could be wrong.
For fuel proofing for nitro I used Nelson's Hobby Specialties clear but he is now out of business. I am strictly a gas guy now so I don't really have to worry about it.
Cliff,
You can apply the PolyC directly to the fabric. Thin the PolyC approx 15% with water and brush on light coats lightly sanding between coats after the 2nd coat.
Anthony