The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

34 Fundamentals of Wood/Epoxy Composite Boatbuilding
point in heating materials much over 100°F (38°C) since
excess heat can boil away portions of the epoxy formulation,
so we prefer 750°F (399°C) hot air guns to more
powerful models. Try to avoid blowing air into mixed
epoxy and warm it gently with adequate ventilation. If
the mixture foams, it has probably boiled and will no
longer be reliable. Heat guns can ignite combustible
materials, so be careful whenever you use them.
Heat lamps and regular light bulbs can be used locally
to raise the temperature of joints as they cure and to
warm containers of resin and hardener. When we want
a small part to cure, we often put it in a “hot box” with
a light bulb. Rigid sheets of foil-backed foam insulation
make cheap and easy warming compartments for
supplies and set-ups. Lamps present significantly fewer
fire risks than heat guns, but they should still be used
with caution.
If WEST SYSTEM resin is stored in very cold or freezing
temperatures, crystals may appear in the resin. If this
happens, boil a pot of water large enough to hold the
container, remove it from direct heat, and carefully put
the can of resin in the water bath. Remember to remove
the container’s lid to avoid the possibility of bursting
the can. Stir the warming epoxy well with a clean stick
until the liquid regains clarity and all crystals at the
bottom of the container are dissolved. <strong>The</strong>n replace the
lid and shake the resin well to melt any crystals which
might be clinging to the top of the container. If you
suspect that resin in your pump has crystallized, pump
warmed resin through it to remove the crystals.