Like Nick said in an earlier post, once the epoxy crystallizes in a pump, it's probably shot. I caught a crystal of epoxy on the edge of my plunger seal. I didn't know it, and it sat that way for a month or so and deformed the seal. Even after a good cleaning, it was never quite the same.

Definitely keep the epoxy warm. Cold isn't necessarily bad for either the pump or the epoxy, but it's bad if the two are combined!

Shawn

> I expect the seal on the plunger leaks. If the epoxy is stiff or for some
> reason the free flow of epoxy up into the pump is impeded, air will be
> sucked in around the seal.

> To avoid this - as much as possible - keep your epoxy warm. Some people
> keep it in a box with a heating pad or light bulb. This lowers the
> viscosity of the resin as well as preventing crystalization.