The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Coating and Finishing
Broadly, the coating and finishing techniques offered in this chapter have stood the test of time. Yet
wood/epoxy technology has evolved, and we’ve learned a great deal since the book was last revised.
Generally, our recommendations now are a bit more conservative than in earlier editions.
We now more strongly recommend applying multiple thin uniform coats of epoxy on a given day to
minimize trapped air bubbles, to have better control of coating thickness, and, in the end, to have more
epoxy on the surface because fewer sanding steps have been required. We are less inclined to flocoat
flat panels with a single heavy coat of epoxy or recommend applying a single coat per day and sanding
before applying another coat.
We also now give more attention to preparing cured epoxy surfaces before recoating. We always recommend
washing with water and sanding cured epoxy coatings before recoating, whereas in previous
editions, we suggested that no surface preparation was necessary unless blush was observed on an
epoxy surface.
Because of concern over surface contaminants, we do not recommend using rags for applying solvents
prior to applying epoxy. If solvents are applied at all, they should be applied with plain white paper towel.
Paints and varnishes in many cases have changed since earlier editions due to environmental concerns
over solvents. Waterborne coatings have gained popularity but still typically are not as durable as the
premium two-part polyurethane paints and clear coatings. If you are planning to use waterborne coatings,
be sure to do some testing to verify satisfactory results.
In Chapter 3, we explained the theory behind sealing
wood with WEST SYSTEM ® epoxy. Here we provide
detailed practical instructions on applying epoxy
coatings and on finishing coated wood surfaces. We
like to keep boatbuilding simple, so in our shop we
continually try to make these necessary jobs as quick
and efficient as possible. We continue to modify and
improve our techniques and tools as we find better
ways to do things.
One of the best things about WEST SYSTEM epoxy is that
it’s easy to finish. A properly coated wood surface has a
hard, durable, stable, and moisture-resistant base for
painting and clear coating. Special finish preparations
are rarely necessary because most finish systems readily
adhere to epoxy-coated wood. Since the moisture
content of the wood beneath the final epoxy coating is
under control, paint and varnish tend to last longer.
In most roller and brush coating procedures, use the
standard application sequence which is detailed in this
chapter. Apply an initial coating of epoxy as evenly as
possible and let it cure. Lightly sand high spots, “fuzz”
and bumps until they are smooth, fill staple holes, and
CHAPTER
15
Figure 15-1 Coating the exterior of an IOR 1 ⁄2-ton racer. This
boat has a natural finish. All fairing, finish sanding, and coating
were done prior to removing the hull from the mold.
apply a second coating. Proceed in this manner until
you have applied as many coatings of WEST SYSTEM
epoxy as you think necessary and prepare your surface
for final finishing. For protection against moisture and
moisture vapor, you should have at least two net coats
of epoxy remaining after sanding and finishing.
An alternate technique for coating with epoxy is
somewhat quicker than the standard roller-brush