Oh, if you\'re going to buy it in quantity you should know about storage. Epoxy putties ages but this process can be slowed quite a bit by freezing it. Keeping the two components separate should also help according to Polymerics.
By the way, how fast it ages depends very much on climate. The warmer, the faster. In a desert it could go off in a few weeks while over here in the Netherlands it can take more than a year (I still have a testbatch standing here, and it just will not develop any skin!).