105 Epoxy Resin is the base material on which all WEST SYSTEM 105 System epoxy compounds are built. It is a clear, pale yellow, low-viscosity liquid epoxy resin. Blended with hardener at the proper ratio, it cures to a hard, solid plastic with superior physical properties. Based on which hardener you choose, it cures at a wide range of temperatures. Once cured, it forms a high-strength solid that is functionally waterproof, and highly resistant to moisture vapor.