WEST SYSTEM206 Slow Hardener® is a low-viscosity epoxy curing agent for use when extended working and cure time is needed or to provide adequate working time at higher temperatures. 
When combined with 105 Resin in a five-part resin to one-part hardener ratio, the cured resin/hardener mixture yields a rigid, high-strength, moisture-resistant solid with excellent bonding and coating properties. 
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)
 
WEST SYSTEM 205 Fast Hardener is a medium-viscosity epoxy curing agent. 
It is used in a majority of situations, at lower temperatures and to produce a rapid cure that develops its physical properties quickly at room temperature. 
When mixed with the 105 Resin in a five-part resin to one-part hardener ratio, the cured resin/hardener mixture yields a rigid, high-strength, moisture-resistant solid with excellent bonding and coating properties.
 
Pot life at 25°C: 10 to 15 minutes
Cure to a solid state: 5 to 7 hours
Cure to maximum strength: 5 to 7 days
Minimum recommended temperature: 5°C
 
WEST SYSTEM 207 Special Coating Hardener™ provides an extremely transparent finish in coating applications and also excellent adhesion for bonding applications.
It contains an ultraviolet inhibitor to protect the 105/207 mix against sunlight. However, the cured epoxy surface still requires long-term UV protection with a quality marine paint or a UV filtered two part varnish. 
 
Blush-free 207 Special Coating Hardener was developed for coating and fibreglass cloth application where an exceptionally clear, moisture-resistant, natural wood finish is desired. Blended with 105 Epoxy Resin, 207 Hardener will not blush or turn cloudy in humid conditions. Thin film applications roll out and tip off smoothly, requiring less sanding in preparation for finish coatings.
Professional and first-time builders like 207 Special Coating Hardener because it is reliable, easy to use, as does not blush. Three coats or more can be applied in one day without additional surface preparation. Fewer coats are required to fill fibreglass weave and in most cases, the final coating can be sanded the following day. Boats can be built faster. Builders also appreciate the excellent fibreglass wet-out characteristics achieved with 105 Resin/207 Special Coating Hardener, yet it won’t drain from vertical surfaces like the very slow curing, low-viscosity epoxies.
105/207 Epoxy has strong physical properties, so it can be used as a structural adhesive for gluing and laminating. It has excellent compatibility with paints and varnishes. An ultraviolet inhibitor in 207 Special Coating Hardener helps provide a beautiful, long-lasting finish when used with quality UV filtering varnish. 105/207 cures clear and colourless.
Mix Ratio: 3 parts resin : 1 part hardener
Pot life at 25°C: 20 to 30 minutes
Cure to a solid state: 9 to 12 hours
Cure to maximum strength: 5 to 7 days
Minimum recommended temperature: 16°C