I'm doing my third warbird with WBPU. Make sure to seal the balsa sheeted areas so that the WBPU does not warp the balsa. I use minwax sanding sealer. On the first two planes I used fiberglass, but this one I am trying polyester dress lining. For $12 I got 3 yards of it at Walmart. A couple of coats of WBPU, talc and water filled in the weave. Sand it down with 320 grit for a smooooth finish. I then spray it with a light coat of high build auto primer. I'm going to try latex paint this time also.