How long do epoxies really take to cure?

Room temperature cured epoxies can take up to a month to fully cure. Even at this point they may not be fully cured due to the presence of low levels of both epoxy and amine materials still not cross-linked. Heat curing will advance the cure to the best that can be achieved, and typically 16 hours at 40°C is reputed to cure epoxies to the maximum level that they would be expected to cure at room temperature. Post curing will also even out the cure of various areas cured at different times of the year. Post curing at higher temperatures may or may not improve the actual cure of room temperature cured epoxies depending on their exact formulations, but will usually help to make the epoxy somewhat tougher as usually its degree of stiffness is decreased slightly as more heat is used to cross link it.