Epoxy vs. Resin Epoxy Epoxy is an excellent high strength adhesive and is one of the most valuable tools available. It is popular because of its cost, strength, and fast set time. It is used more for laminating because it is stronger then Polyester Resins. Epoxy must be mixed witha hardener and is available in flowing and knife grades. Tints are available. Standard shelf life is two years from the manufacturing date. Polyester Resin Polyester resin is used for laminating, seaming, and repairs. Polyester resin sets quicky and is easy to tint. Polyester resin uses an activator rather than a hardener and the activator must be measured properly to avoid a thermal reaction that will reduce the strength of the resin and can damage the stone. Standard shelf life is one year from the manufacturing date. Acrylic Resin Acrylic resin is a water clear adhesive and filler. Although Acrylic resin is not as strong as Polyester resin, Acrylic resin is popular for its water-clear appearance. Like polyester resin, Acrylic resin is available in both flowing and knife grade an it uses an activator rather than a hardener. The activator must be measured properly to avoid a thermal reaction that will reduce the strength of the resin and can damage the stone. Too much activator may also cause the Acrylic resin to yellow. Standard shelf life is one year from the manufacturing date.