This stuff is mixed 5 to 1 so if the pumps were mixed up or both the same it would cause some fireworks. I've had it get pretty warm when mixing big batches but never seen it smoke or pop, that would definitely be exciting!

Bud has it right.

Keep in mind the hot batch will set up hard very hard and very brittle, the slower the cure the more durable the lay up. The stuff also gets hotter if left in a big mix, spread out, the heat disipates but left in the pot you can get a thermal runaway as it reaches critical mass, once the catalyst kicks it gets hot, the hotter it gets the quicker it gets hot. You had a catalytic Chernobal.

I hate hot batches, when they kick it takes days to get the smell out of my mustache. And in a few years you will see spider web cracking because it is to brittle.

[QUOTE=plaineolde;8336]I'm curious what the shelf life of epoxy might be. I have some West System 105 epoxy, 205 hardener, that I've had on the shelf for a long time, could be 10 years. I used some last year for a wood project at home. It seemed to work just fine, however, it got REALLY hot when mixed (3 pumps from the 105 and 3 from the 205). It melted and blistered the plastic container I used to mix it, smoked and popped; pretty exciting 15 minutes. [/QUOTE]

The West System manual "Fiberglass Boat Repair and Maintenance" (available at [url]www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-a... - a handy free book!) has this to say at page 78, under the caption "Shelf life":
"If the containers are kept sealed when not in use West System resin and hardeners should remain usable for many years. Over time, 105 Resin will thicken slightly and will therefore require extra care when mixing. Hardeners may darken with age, but physical properties are not affected by color. Mini Pumps may be left in containers during storage. It is a good idea, after a long storage to verify the metering accuracy of the pumps ...."

I melted a plastic container once that way, too, after leaving it unattended for too long; you can avoid this problem from exothermic heating by pouring the mixture into a wider container with greater surface area.