Is 5 minutes too short? 30 minutes too long? Well, how about 15 minutes, then? Perfecto! Seriously, I have used this and other cure time, Hobbylinc Branded Epoxies with great success. I have mixed it with micro balloons to form fin fillets that are sturdy and sand very well. My best trick so far was laminating a BT-80, 2.6 inch diameter body tube with this epoxy and petite sized pantyhose for an extremely lightweight glassed tube for a jumbo sized Estes Streak model rocket. Seriously, you needn't pay more for excellent, 2 part epoxy!