Thanks for the tip on the 3rd container and the wire. I was only using two cups, one for each part, and was using a wooden stick to stir them with.
I appreciate the info guys!
As for doing it early, I hear ya but the rubbery part was well after a week or so, which means I'm screwing up the mixing process. Some batches were fine while others continued to be rubbery for weeks after. So, I'll try the tips above and see how it goes. Thanks!