Slow-Cure 30 Minute Epoxy has the highest strength of our epoxies. It is waterproof and more heat resistant, and can be used for bonding if you’re willing to wait overnight. Fillers can be mixed with it to form a putty-like consistency. Such fillers will usually decrease the working time by about 25%. Bonded objects can be handled after 8 hours and the cured epoxy reaches full strength within 24 hours.