Epoxy crystallization can occur in foods, minerals, and epoxy resins or curing agents. Recognizing the phenomenon can help you ensure your material is properly prepared before attempting a cure.
What is epoxy crystallization?
Crystallization is the natural solid state of a product
Epoxy resins and hardeners can all experience crystallization
It primarily occurs with two component epoxy systems, but can also occur in one component heat cure epoxies
Crystallization does not mean defective material
How to recognize epoxy crystallization?
Cloudiness, free floating crystals, crystal masses, or completely solidified material
What causes epoxy crystallization?
High purity of material
Low viscosity of material
Extreme cold temperatures (-40 °C)
How can you reverse epoxy crystallization?
Heat crystallized material between 50 to 60 °C for 1 to 2 hours. Container size will affect the length of time needed for decrystallization.
Stir material including container sides and bottom to ensure all crystals have been melted and that heat has been evenly distributed.
If crystals are still present, continue heating and repeat stir process until there is no evidence of crystals.
While reversing epoxy crystallization can be effective for some epoxies, avoid this method with one component heat cure epoxies, which cannot be heated to reverse crystallization as product damage may occur.