Get PVA at http://www.aircraftspruce.com/search/search.php . I also searched Wicks' site because I KNOW they have it, but after about a minute of search through everything from tailwheels to foam, I gave up and found it instantly at AS&S. Basically it's used as mold release agent. Wax the mold with mold release wax, then spray a very light dusty coat of PVA (if you put it on wet it'll just bead up on the waxed surface), and then once that dry coat dries, you can put on a wetter coat or two to form the film. Then layup your cowling or whatever, let it cure, and the PVA will pop apart (or will dissolve if exposed to water). Never heard of using it for sanding purposes, but if Lee says it works, it probably does...
Mark Langford n5...@hiwaay.net website www.n56ml.com