SLOW-CUREâ ¢ 30 min. epoxy works best for forming reinforcing fillets on joints. It has the highest strength of our epoxies. It is waterproof and more heat resistant. SLOW-CUREâ ¢ can be used for bonding if youâ re willing to wait overnight. Fillers such as microballoons can be mixed with SLOW-CUREâ ¢ and FINISH-CUREâ ¢ 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. 4.5 oz.