The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 13 – Synthetic Fibers and WEST SYSTEM ® Epoxy 123
lightly. <strong>The</strong>n do a more thorough job on all puttied areas
until you have removed the fuzzy feel of the cured epoxy
and the filled spots are fair and smooth. We usually use
a 2,000 rpm electric polisher with a 7" soft foam disc
pad and 80-grit aluminum oxide paper for this job,
but a sanding block and 50 or 80-grit paper will also
work. Vacuum or sweep the surface to remove all
residue. Particles the size of sand granules can help
trap air between substrate and cloth and cause serious
bonding problems.
Applying Fabric
All fabrics can be applied to surfaces in one of three
general methods. <strong>The</strong> dry method, applying fabric to
a dry surface, has several advantages. <strong>The</strong> fabric is easy
to control and, because you can use limited quantities
of epoxy at any time, there is no rush. It is an easier
method for one person to manage. Applying fiberglass
where a clear finish is desired, such as stripper canoes
and kayaks, requires some special considerations and a
variation of the dry method. <strong>The</strong> dry method for clear
finishes uses WEST SYSTEM 105 Resin combined with
207 Special Coating Hardener. <strong>The</strong> 105 Resin/207
Hardener combination is preferable for areas that will
be naturally finished for both the dry method and the
wet method.
<strong>The</strong> dry method will not work on overhead and vertical
surfaces, so in those areas, you need to rely on a wet
method, that is, applying fabric to a surface coated
with wet epoxy. With the wet method, speed is of some
importance because the timing of the operation is
affected by the initial surface coating. This method can
be tricky, especially overhead, and may require the
organized efforts of two or three people.
<strong>The</strong> Dry Method
If the surface is fairly flat, lay the cut cloth over it and
smooth all wrinkles. Use staples or masking tape to
hold it in place, slightly overlapping any cloth joints.
When the material is in position, pour mixed epoxy
directly on the fabric. Begin by mixing small quantities
of epoxy and increase batch size as you gain more
experience. Use a flexible plastic spreader or squeegee
to spread the epoxy and to remove any pools which
form. Firm pressure is necessary, but don’t press so
hard that you shift the cloth.
Figure 13-1 Applying fiberglass to the deck of the 60'
(18.2m) proa Slingshot using the dry method. Applicators
have wet out the glass cloth around the daggerboard slot
and are working toward the bow and stern.
<strong>The</strong> Dry Method for Clear Finishing
Take special steps if you are applying fiberglass to a
naturally finished hull and want it to be clear and
transparent. Pouring a puddle of epoxy on the fiberglass
cloth and spreading it around with a spreader, as
described in the dry method, is a quick way to wet out
fiberglass. However, it may result in a blotchy looking
fiberglass job because the puddle area has much less air
trapped in the fiberglass weave than the surrounding
area to which the epoxy was spread. This does not create
a problem if the surface is to be painted, but if you are
aiming for a naturally finished surface, the techniques
described in Figure 13-2, while a little more time
consuming, will yield a better looking job.