Crystallization in Epoxies: How to Spot it and Fix It.

 During the winter months we sometimes receive calls from customers who have experienced the resin part of our epoxy kits crystalizing or appearing congealed. This however is a normal occurrence in epoxies which have been exposed to cold temperatures either in storage or during transit when being delivered. 

 How to identify crystallization in Epoxy.

Just like with water in the freezer, ice crystals will begin to form as the water changes to ice, this is the same with Epoxy. As the epoxies start to crystalize you will see little white Granules or in worst case scenario the epoxy will look Foggy or Milky or solidified altogether.


 Why has this happened.

Data sheets will often tell you how to store your Resins and Hardeners and at what temperature. Although we as a supplier follow these recommendations the epoxy can still be exposed to cold temperatures during transit which is beyond anyone’s control.

Also, it could be that the user has stored the product in a cold shed or garage over a period and the epoxy at some point has been exposed to cold temperatures before its next use.

Concrete floors can get extremely cold at night even during warm seasons so it’s a good idea to keep it off the floor when stored in a garage or workshop.

Rest assured however, the material has not gone bad. Once you return the epoxy to its clear liquid state, it is perfectly usable and still has the same performance properties.


How to return the material back to its normal state.

Now that you know what Crystallization of epoxy is, you can take preventive measures to reduce the chance of it happening, but if the Epoxy has already been affected by crystallization you can take the following steps to remedy it and avoid delays to your project.


Crystals can be eliminated by increasing the temperature of the liquid resin to about 50°C until all signs of the crystals are gone. Usually this can be done by resting the epoxy on a radiator. Some brands recommend putting the container in hot water but be careful to ensure the tub is tightly closed and that water cannot come into contact with the resin.  check the material at 10 minutes, at 20 minutes, at 30 minutes, and at 1 hour. Typically, it takes only 20-40 minutes to eliminate crystals and fully return the epoxy to a clear liquid, but it could take several hours depending on severity. (Note that this low-temperature heat treatment does not damage the epoxy or impact its material properties. Also, the epoxy won’t cure, because you have not yet mixed the material.)  Allow the resin to cool to room temperature, then proceed to use normally.