The resin and hardener are designed to be used together and more specifically for the surfboard hot coat. The chemical reaction between the two products is unique and was developed to prevent the resin from leaking from the board (we call this stage B or gel stage). During step B, the epoxy is a gel and can be moved but tends to stay where you put it. This epoxy/hardener mixture has been the system most used by our customers for many years when it comes to making a hot coat.