Place your tightly capped bottles of resin and hardener in a container of hot ( not boiling ) water. 2. Let the bottles sit in the water bath for 10-15 minutes ( depending on how cold your resin was to start with and how hot your water is. ) 3. Dry your bottles off thoroughly before opening them ( even a single drop of water in your resin or hardener can cause your resin to cure cloudy. ). Since curing is accelerated by heat, be aware that warming your resin in a water bath cuts down your 45 minute working time by about 10 minutes, so time yourself accordingly.