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Softening Crystallised Epoxy Resins

One part of many epoxy resin systems is a pure component. These epoxy components have a tendency to crystallise over time forming an unworkable solid. This process is reversible, and we describe how to reverse that process here.

With Smiths epoxy resins it is the B component that may crystallise. It is the A component of many other manufacturers (there is no standard naming nomenclature for whether A or B is the Epoxy or the Hardener). Regardless of the manufacturer, if one part of your epoxy resin has gone hard or crystallised, try this before throwing it away.

Which resin systems may crystallise?

Our Clear Penetrating Epoxy Sealer will not crystallise. The solvents in it stop it crystallising.

The following of our epoxies will however crystallise eventually:

How to De Crystallise Hardened Uncured Epoxy Resin

There are two alternative methods of removing the crystals in your epoxy resin. Both work and bring the resin to a liquid form and then allow it to set slowly.

Oven Method of Softening Hardened Epoxy Resins

  1. Set your oven to around 50 degrees Celcius
  2. Put your Part B container in the oven
  3. Wait till the contents are heated through (This may take a while)
  4. Turn the oven off and wait for the contents to cool

Hot Water Method of Decrystallising Hardened Epoxy Resin

  1. Take a large-ish saucepan big enough to nearly fully immerse the container in
  2. Now put the Part B container in a waterproof plastic bag. This will protect the outer packaging.
  3. Stand the container (B part of Smiths) in it
  4. Then add water to within 1″ of the top seam of the container
  5. Remove the container
  6. Now bring the water to the boil
  7. Then take the heat off the water, put the container in the hot water (you may need weight to hold it down if it is filler)
  8. Finally leave the water to cool – the epoxy will be de-crystallised once you have done this

Which Epoxy Resins can Crystallise

Fill-It part B epoxy resin can Crystallise

Any pure epoxy resin component can potentially crystallise. Fill-It filler part B crystallises if stored at a low temperatures for a long period. Reverse this process by following the instructions above.

Crystallisation of Epoxy resin Resources

More information on this phenomenon may be found here: Crystallisation in Expoxies