205 Fast Hardener is a medium-viscosity epoxy curing agent. It is useful in a majority of bonding situations, and at lower temperatures. 205 Fast Hardener produces a rapid epoxy cure that develops physical properties quickly at room temperature. Mix it with WEST SYSTEM 105 Resin in a five-part resin to one-part hardener ratio. The resulting cured epoxy is a rigid, high-strength, moisture-resistant solid. The combination of 105 Resin/205 Fast Hardener has excellent bonding and coating properties.