Crystallization means that the epoxy resin or hardener has converted from its liquid form into solid crystals. It typically occurs because the epoxy was subjected to low temperatures or contaminated with moisture or dust. Do not use any material that has become crystallized until it has been returned to the liquid state.
A simple way to liquefy crystallized resin or hardener is to place the bottle in a water bath. The water temperature should be 140-150°F; change the water, as needed, to maintain this temperature. The material should be liquefied in 1-2 hours.
To prevent crystallization, store resin and hardener products in a dry place that is 60-90°F. In cold weather, store products on a raised surface (off the floor), and don't store any products near outside doors or walls.