206 Slow Hardener is a low-viscosity epoxy curing agent for use when extended working time or a longer cure time is needed. It also provides adequate working time at higher shop temperatures. When combined with 105 Resin in a five-part epoxy resin to one-part hardener ratio, the cured resin/206 Slow Hardener mixture yields a rigid, high-strength, moisture-resistant solid with excellent bonding and barrier coating properties. 206 Slow Hardener is not intended for clear coating.
Pot life at 72°F (22°C): 20 to 25 minutes
Cure to a solid state: 10 to 15 hours
Cure to maximum strength: 1 to 4 days
Minimum recommended temperature: 60°F (16°C)
Video: Dispensing and Mixing WEST SYSTEM Epoxy.
No Need for Excessive Clamping Force
Unlike traditional wood glues, WEST SYSTEM 105 Resin-based epoxy mixtures including 105 Resin and 206 Slow Hardener are stronger than wood or many other substrates. Because of this, it is beneficial to have some epoxy between the objects you are gluing together. As long as the parts are held in place and epoxy is contacting the entire surface of both substrates, no clamping pressure is needed. With epoxy, the goal clamping is to simply ensure the epoxy contacts the entire surface for the duration of the cure time. Moderating clamp force is all that is required.
If an epoxy filler is not used and a high clamping force is used, the result can be a glue-starved joint which will make bond failure much more likely. Glue starved joints are weaker than their counterparts. Avoid glue-starved joints by following the one- or two-step bonding method.
Read more about glue-starved joints and other epoxy considerations at Epoxyworks.