When mixing TotalBoat 2:1 Slow Hardener with TotalBoat High Performance Epoxy Resin, 55°F is the minimum temperature recommended for application. Temperatures colder than advised in the Technical Data Sheet will increase the viscosity and extend the cure time. Colder temperatures can even result in the epoxy not curing properly, if at all, because at temperatures below 35-40°F, the epoxy isn't able to generate enough heat to cure. If the epoxy does eventually cure in temperatures that are cooler than advised, the performance attributes and cosmetic properties may be adversely affected.