Epoxy that has been allowed to freeze, or stays below the product's stated storage temperature may be subject to crystallization. The components can look cloudy and feel firm. Crystallization can also be scattered in the product, feeling like sand or little crystalline pieces.
To return crystallized epoxy components to a usable liquid state, simply put the container in a warm water bath until the epoxy material inside the container reaches 120-130°F. The water temperature should be 140-150°F. Change out the water, as needed, to maintain this temperature. Stirring gently or lightly agitating the container every few minutes during this process can help break up the crystals and speed up the process.
To prevent crystallization, store your resin and hardener products in a dry place where the temperature range is 60-90°F. In cold weather, store products on a raised surface off of the floor, and do not place any products near outside walls or doors.