209 Extra Slow Hardener® is formulated for use with WEST SYSTEM® 105 Epoxy Resin® or general coating and bonding applications in extremely warm and/or humid conditions or when extended working time is desired at room temperature. Provides approximately twice the working time of 206 Slow Hardener®. 105/209 forms a high-strength, moisture-resistant solid with excellent bonding and coating properties. The mix ratio is 3 parts resin to 1 part hardener by volume. Not intended for clear coating.