Cure your substance in a very cool place. Once, I was encapsulating a product, and my boss turned off the A/C to try to save on the utilities, as the normal work day had ended. The epoxy I was using actually boiled over and made a HUGE mess! Recently, I encapsulated the back of some multiple contactor connectors by just forming a dam with tape around the connector body, the top edge of the tape protuding to the level I want to fill with epoxy. Didn't look pretty, but man it really worked!