Apparently cellulose is actually a polymer, I didn't realize, but frankly that suits my point even more because my point is this : it's absurd to say that polyurethane is the only plastic and you're not presenting evidence that fullerplast is urethane. You're spouting off the same hearsay as everyone else on every forum. I can say a couple things for certain on the subject. I've seen vinyl used as a wood sealer. Fender was forever using DuPont acrylics for custom colors. If the point of switching to urethane was to make a more durable finish it would be very backwards to start with the sealer or undercoat. I've seen 60s guitars naturally worn thru to bare wood and have never seen a verifiably urethane finished guitar wear thru. Urethane cracks and splits and peels. I have urethane guitars that are doing that right this second. It doesn't really bond to the wood per se, it bonds to itself and whatever it is underneath the 60s fender top coats that's opaque chips more like nitrocellulose chips than it does like urethane chips and it very much appears to be bonded to the wood. My money is on vinyl.