System Three General Purpose Epoxy is ideal for wood construction and repair, as well as gel coat blister repair, and general purpose fiberglass repair. It has excellent pot life and cure time control. Can be combined in a 2:1 ratio with different hardeners (sold separately) to provide a continuous range of cure times under different temperature conditions, down to as low as 35 degrees F, and with no limitations on humidity. USA #1 Hardener - A fast drying hardener (15 min.) that will cure in temperatures as low as 35 degrees Fahrenheit. Tack free time is 2 hours at 77 degrees F. #2 Hardener - A medium fast drying hardener (30 min.) that will cure in temperatures as low as 55 degrees Fahrenheit. Tack free time is 4-6 hours at 77 degrees F.