Make sure that the resin and hardener have been mixed together for 3-5 minutes. Also, be sure that the resin is mixed and poured within the 45-minute working time, which starts as soon as the hardener touches the resin in the same mixing cup. Pouring after working time is often the cause of streaks or lines in cured resin. Please refer to the 7 Steps to a Bubble-Free and Flawless Cure at the top of the FAQ.