The shelf life of TotalBoat 4-Minute Epoxy is two years from the date of manufacture, if stored properly and closed tightly after use.
Regardless of the date of manufacture, if the epoxy comes out of the syringe evenly and consistently, with no signs of crystallization or clumping, it is considered acceptable for use. In addition, you can perform a small test sample of older 4-Minute Epoxy to ensure that it cures properly.