I started using a fresh container of GlassCast 10 about 10 days ago using about 2/3rds of the contents.

Today, when I went to use the remaining epoxy, I found is was severely crystallised and not pourable.

There has been no contamination with the hardner.

What has gone wrong, or is there a very short shelf life once the container is opened?

Common issue with epoxies like Glasscast, especially if it has been cold. There's nothing really wrong with it, you can reverse the crystallization by heating it up at 50 or 60 degrees for a few hours and it will be good as new.

As Hanaldo says, the resin has got cold at some point and crystalised.  Sticking it on a hot radiator, oven at 50C or in a sink of hot water for a few hours (lids sealed) is usually enough heat energy to turn it back to a liquid.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant