This week we’ll look at how the resin and hardener combine to
make epoxy and how you can use different hardeners for
different conditions.

This week we’ll look at how the resin and hardener combine to
make epoxy and how you can use different hardeners for
different conditions.

Resins used in marine epoxies are low viscosity. Typically
they are modified by epoxy companies for their use on boats.
Chemically they are biphenyl, or they combine 2 phenols and
1 Acetate.

The resin is mixed with a hardener, which is composed of
polyamines. Chemically, and order wise, these are similar to
ammonia.

The reaction between resin and hardener is exothermic. This
means it gives off heat, meaning that the warmer the
conditions the faster the reaction. Another way to think of
the reaction is as follows: epoxy that is mixed thickly
and is used in warm conditions cures fast, while a thin
mixture of epoxy in cold conditions cures slowly.

Looking at West System epoxy products we see 4 hardeners
that can be mixed with their resin.

205 hardener is the standard hardener, best for epoxy jobs done
at room temperature.

Their 206 hardener has a lower viscosity. This means it
cures slower than 205 and is a good choice for jobs where
the job is an extended one. 206 has a pot life of 20-25
minutes while 205’s pot life is 9-12 minutes.

209 is an extra slow hardener for working in warm
conditions. It has twice the pot life of 206 hardener.

207 hardener is a special use product. If you want a clear,
natural wood finish you should use 207.

Most companies, including West System, produce their resins
and epoxy in a way so that they are easily mixed. Typically
when purchasing resin and hardener you can buy a set of pumps.
These pumps are calibrated so that one pump of resin and one
of hardener automatically produce the appropriate mixture.

Future articles will cover fillers and epoxy techniques.

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