I use MinWax Polycrylic for sealing Solartex on most of my planes.

There are a couple of caveats with this stuff:

1. For sealing Solartex I use 2 sprayed coats. Let the first coat dry about 1 hour before applying the second coat.

2. Let the Polycrylic dry for a MINIMUM of 7 days before exposing to glow fuel.

3. Do not let the residue remain on the finish for longer than 4 hours or the finish will soften. I have found that the Polycrylic is definitely resistant to 10% nitro residue and various reports indicate 15% has no problems either.

The Polycrylic is water based and does not yellow with age as the oild base polyurethane does.

Another option would be to use Ultracote clear. That will provide a more fuel "proof" sealer than than the Polycrylic, however it is only available in Hi-Gloss and is substantially more expensive than the Polycrylic.