asianflava wrote:It's probably the same as epoxy thickened with a lightweight faring filler or microbaloons.
Nope, the stuff Jude used is a polyester filler (the little tube of catalyst is the give-away) and epoxy has much better adhesion than polyester - usually the epoxy filler is stronger than the wood it's stuck to.
Flex wood as much as you like and epoxy filler will stay on - do the same thing with polyester filler and it'll eventually crack off.
Andrew