11 Tips for Using Epoxy

Follow some basic rules

Epoxy is a two-part glue: a hardener and a
resin that combine to form a hard, durable plastic.
It’s important to follow the manufacturer’s
recommendations and use correct ratios of
resin and hardener to ensure the glue cures
fully and reaches its maximum strength.
Epoxy generates heat as it cures; in fact, the
heat helps it cure. The larger the batch, the
more heat it generates. It’s best to mix
small batches to maximize your working
time. If you need a large batch, pour the
mixed epoxy into a large flat container, such
as a pie pan. This has a cooling effect and
increases your working time.

Working with epoxy does require that
you take some precautions. Always
wear protective clothing and
safety glasses when you work
with epoxy. Nitrile or Latex gloves
are a must. Be sure to work in a wellventilated
space or wear a respirator.
Be careful to dispose of used rags in a
covered metal container.

Click any image to view a larger version.

Rescue a loose joint

We all have
moments when we
wish we had left
that tenon just a
whisker thicker.
The gap-filling
properties of
epoxy make it the
perfect solution.
Epoxy can fill
small and big gaps
and still maintain
full bonding
strength. This is
something no
other glue or wood
filler can match.

Tip: Plastic containers are ideal
for mixing, because the epoxy
simply peels out after it sets and
the container can be reused.

Glue metal to wood

Epoxy bonds many kinds of
materials to one another, including
wood, metal, fiberglass, masonry,
tile, concrete and plaster. It will not,
however, bond to most plastics.

Tip: On anodized metal surfaces, such
as aluminum T-track, you must sand off
the coating before gluing. Epoxy doesn’t
stick well to anodized surfaces.

Renew a stripped screw hole

Simply fill the hole with epoxy. When it
has cured, predrill for the screws and
reinstall the hinge. You can also let the
epoxy cure with screws in place for a
permanent attachment. If you want to
make the screw removable, apply a
coating of oil to the threads before pushing
the screw into the wet epoxy.

Tip: On a vertical surface, it’s nice to have
an epoxy that won’t run. Gel epoxy is the
perfect choice. It has a consistency similar to
that of petroleum jelly. You can even make
your own gel epoxy by adding a thickener.

Make an epoxy inlay

Rout a 1/8-in. x 1/8-in. groove and
mask around it with tape. Mix a
batch of slow-setting epoxy and
add a colorant. Powder tempera
paint works well. Add thickener (see
Sources, page 26) until the epoxy is
the consistency of petroleum jelly.
Apply enough epoxy to the groove
so it sits slightly above the surface
of the wood. After the epoxy sets
but is still slightly soft, remove the
tape. When the epoxy has fully
cured, sand it level.

Use when clamping is awkward

Epoxy forms a mechanical
bond and needs only contact
pressure to adhere.
Use quick-setting epoxy,
press the parts into place
with your fingers and the
job will be done in only a
couple of minutes.

Tip: Wood is a porous material
that absorbs epoxy. Applying it
to both surfaces will ensure that
enough is left unabsorbed to
bond the two parts together. If
you do use clamps, don’t turn
them too tight or you will
squeeze out too much glue and
starve the joint.

Waterproof outdoor projects

When used as an undercoat
or sealer, brushable
epoxy greatly reduces
expansion and contraction
in wood. Coat all
parts prior to assembly
and make sure epoxy
gets down into the fastener
holes. If the wood
absorbs a lot of the
epoxy, sand the first coat
after it cures and apply a
second coat. Epoxy is not
UV-resistant, though, so
you must topcoat your
project with exterior varnish
or paint. The
extremely stable epoxy
base coat also means that
your topcoat will last
much longer before refinishing
is necessary.

Sources

(Note: Product availability and costs are subject to change since original publication date.)

Devcon, devcon.com, 800-933-8266, Fast- and slow-cure and gel epoxies.

Loctite, loctiteproducts.com, 800-321-0253, Fast- and slow-cure and gel epoxies.

Super Glue, pacertech.com, 800-538-3091, Fast- and slow-cure and gel epoxies.

System Three Resins Inc., systemthree.com, 800-333-5514, Fast- and slow-cure and brushable epoxies and fillers.

West System, westsystem.com, 866-937-8797, Fast- and
slow-cure and brushable epoxies and fillers.

Zap, pacertech.com, 800-538-3091, Fast- and slow-cure and brushable and gel epoxies.

This story originally appeared in American Woodworker July 2005, issue #115.

July 2005, issue #115

Purchase this back issue.