I built my boat in a cold basement and lost both my pumps over the course of the winter to what I suspect was critalized resin/hardener . I also noted that I was going through the two at a different than 2:1 ratio. Though I never had any trouble with the mix curing, I switched measuring cups made from clear party glasses after the pumps started burping on every other pump.

For smaller batches I used the measuing cups that come with cough medicine. For some reason we had a number of them hanging around and any unused portion pops out when you flex the cup the next day.

> Your mileage will vary, but if you keep the pumps in the jugs and store
> the jugs in a warm place, the pumps should be usable for a long time. They
> may need to be reprimed before you start. If the pumps get cold while wet
> with epoxy, the epoxy may crystalize. Reheating should make the pumps work
> again, but they never seem to be the same and they will probably burp.