Exothermic Epoxy


When epoxy cures it releases heat in an exothermic reaction. I was adding some glass-fibre reinforcement to the telescope tube and mixed 140 g of L285 epoxy into an ordinary plastic cup. I got about half-way through the job when I noticed the cup heating up. I tried putting it in a cold water-bath, but it was too late by then... It quickly got very hot and all of it cured instantly! At room temperature this resin should have a 60 min pot-life, but now it cured in about 5 minutes. Not much harm done, but I understand these things can cause fires and all kinds of trouble when people deal with kg or tens of kg amounts.

Note to self: 100 g or more of L285 needs to be mixed in a shallow container with lots of surface-area which provides cooling. RTFM.

Does anyone else have pictures or stories about exothermic melt-downs?

2 thoughts on “Exothermic Epoxy”

  1. Doh! I did exactly this in the weekend. My first batches were mixed in a container that was wider. This time around I mixed in a plastic "beer" cup similar to the one pictured above. I noticed a slight amount of steam coming off after fives minutes, and it all set rock hard in minutes. No great loss, but was instructive in the mixing of epoxy.

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