The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 13 – Synthetic Fibers and WEST SYSTEM ® Epoxy 125
<strong>The</strong> Wet Method
If you are working on a vertical or overhead surface, lay
out and fit the fabric. <strong>The</strong>n roll it back on a cardboard
tube or PVC pipe for easy handling. Mix resin and
hardener, apply a coating to the substrate, and wait
until it thickens slightly. <strong>The</strong>n lay the cloth into the
epoxy, sliding it into position. Surface tension will
usually hold the cloth where you want it, but when
you are installing heavy cloth overhead, you may need
staples to prevent drooping. We find that the entire
process is much more successful when one person
holds the tube of cloth and one or two others position
it and smooth out wrinkles. As soon as the cloth is
positioned where you want it, roll on more epoxy. Wet
out the cloth completely and remove any air bubbles,
using a plastic spreader to squeegee the surface as you
would with the dry method.
With the wet method, application area is limited by time
and the number of workers. If you use a slow hardener
(WEST SYSTEM 206 or 207), you will have only about an
hour from the time you first coat the surface to complete
the procedure. This is usually adequate, but if you are
inexperienced or have problems convincing friends to
share in the fun, start with smaller areas and work up
to big surfaces as you become more capable.
An alternate wet method allows one person to apply
glass to vertical or overhead surfaces. <strong>The</strong> technique is
similar to hanging wallpaper. Cut the standard glass roll
Figure 13-3 Applying polypropylene cloth to a 45' outrigger
hull using the wet method.
Figure 13-4 Wetting out the fiberglass cloth on a wing mast
for the 60' proa Slingshot. In this application, 4 oz cloth was
draped over the spar and wet out with rollers.
in half. A typical roll is 60" (1500mm) wide (4 oz
glass is 50" (1250mm) wide). A 30" (750mm) wide
roll is much easier to handle. Wet out an area of the
hull with unthickened epoxy wider than the cut strip.
Cut the glass strip to length and wet it out on a protected
work surface. Roll the wet fabric onto a cardboard tube.
Position the edge of the glass against the hull. Press the
fabric against the hull and smooth it out with one hand
as you unroll it with the other. (See Figure 13-5.)
Whether you use the wet or the dry method, the point
of the squeegee process is to saturate the weave of the
cloth and then to remove any puddles of excess epoxy
which might cause the fiberglass to float from the
surface. Squeegeeing also helps to loosen air which
might be trapped in the cloth/epoxy matrix. A properly
squeegeed surface has a matte finish and its weave
should be only about two-thirds filled with epoxy.
Don’t try to fill it completely at this point—later
coatings will take care of the problem. As you work,
watch for areas of cloth that haven’t received enough
epoxy. Dry spots may be difficult to see, but they
usually look dull and slightly white. It’s especially
important to prevent them on surfaces that will be
naturally finished because the cloth will remain
visible if it is not wet out completely.
Whichever method you use, remember that the epoxy/
cloth matrix is easiest to trim when it is only partially