Open it upÊnow. The longer youÊwait the harder it gets. Epoxy takes many days to get really sandable hard. Don't panic - it's still quite flexible and will remain so for a while. If yours closed up, spread it a bit byÊclamping it to flat 2 x 4 pieces which will open it up. You can probably do it by hand and then put some straps over it keeping it flatter on the 2 x 4s. Since decks are relatively flat, they don't fold in with the force that a strip hull can.