This may be too easy but I was sitting down to work on a repair on my Right Flyer Trainer. I wanted to work on the firewall and forgot previously to ask a seemingly obvious question. I don't know what was originally used to fuel proof since my plane is an ARF, but any suggestions on removal so I can epoxy replacement A/C plywood parts will be helpful.
Thanx! Ron

Sandpaper.

Check the firewall to see if it is "glossy" or has a finish on it. MANY ARFs come through WITHOUT any fuel proofing on the firewall. If it has a finish or is glossy, use sandpaper to remove it. A couple of good fuel proofing surfaces are: Dilute some epoxy with about 30% (by volume) of acetone, mix it well and brush on and let dry. Use clear AeroGloss Brand dope, or any dope that states it is fuel proof.

I prefer the epoxy/acetone method even though it takes 24 - 48 hours to dry.

Just gouge the area with a file or even a razor blade to give the epoxy something to stick to. For larger areas, you could even drill a few small holes part way into the wood.

Or really coarse sand paper. Rough it up really good so the epoxy will stick. Beef it up with triangle stock if needed.

Thanks to all for the help. I put in some hours in this weekend and the Right Flyer is almost ready to return from the "Rework Facility" and check flight..