Careful measuring of epoxy resin and hardener and thorough
mixing are essential for a proper cure. Whether the resin/hardener mixture is applied as a
coating or modified with fillers or additives, observing the following procedures will
assure a controlled and thorough chemical transition to a high-strength epoxy solid.
Dispense the proper proportions of resin and hardener into a clean
plastic, metal or wax-free paper container (Figure 2). Don't use glass or foam containers
because of the potential danger from exothermic heat build-up.
DO NOT attempt to adjust the epoxy cure time by altering
the mix ratio. An accurate ratio is essential for a proper cure and full development of
- Dispensing with Mini pumps - Most problems
related to curing of the epoxy can be traced to the wrong ratio of resin and hardener. To
simplify metering, we recommend using calibrated West System Mini Pumps to dispense the
resin and hardener. Mini Pumps are calibrated to deliver the proper working ratio of resin
Pump one full pump stroke of resin for each one full pump stroke of hardener. Depress each pump head fully and allow the head to come completely back to
the top before beginning the next stroke. Partial strokes will give the wrong ratio. Read
the pump instructions before using pumps.
Before you use the first mixture on a project, verify the proper ratio according to the
instructions that come with the pumps. Re-check the ratio anytime you experience problems
- Dispensing without Mini Pumps
(Weight/volume measure) - To measure 105 Resin and 205 or 206 Hardener by weight or
volume, combine five parts resin with one part hardener. To measure 105 Resin and 207 or
209 Hardener by volume, combine three parts resin with one part hardener (by weight, 3.5
parts resin-1 part hardener).
First time users
If this is the first time you have used WEST SYSTEM epoxy,
begin with a small test batch to get the feel for the mixing and curing process, before
applying the mixture to your project. This will demonstrate the hardener's open time for
the temperature you are working in and assure you that the resin/hardener ratio is metered
properly. Mix small batches until you are confident of the mixture's handling
Stir the two ingredients together thoroughly-at
least 1 minute-longer in cooler temperatures (Figure 3). To assure thorough mixing, scrape
the sides and bottom of the pot as you mix. Use the flat end of the mixing stick to reach the inside corner of the pot. If you are using a power mixer, occasionally scrape the
sides and corners of the mixing pot while mixing.
If you are going to be using the mixture for coating,
quickly pour it into a roller pan to extend the open time.
WARNING! Curing epoxy generates heat. When contained, a large mass of
curing epoxy has a very short pot life, and can generate enough heat to melt plastic and
foam, burn your skin and ignite combustible materials. For this reason do not use foam or
glass mixing containers. If a pot of mixed epoxy begins to exotherm (heat up), quickly
move it outdoors. Avoid breathing the fumes. Do not dispose of the mixture until the
reaction is complete and has cooled. Do not fill or cast layers of epoxy thicker than
1/2"-thinner if enclosed by foam or other insulating material. Do not pour into