The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 11 – Laminating and Bonding Techniques 95
to hunt around for them and can position each clamp
as quickly as possible.
Clamps are usually heavy and cumbersome, and they
can take a lot of time to position and tighten. It is
extremely important, before laminating begins, that
there is a reserve of clamps close by, that they are of
sufficient size, and that they have been checked for
workability (i.e., that no glue lumps are on the threads).
Whenever we are preparing for laminating without the
luxury of a dry run, we line up more clamps and clamp
pads than we actually think will be needed and place
them at various intervals around the laminating area for
quick access. For speed, we recommend that you use
the adjustable bar-type clamps rather than C-clamps,
which take much longer to fit into place. If you do use
C-clamps, we suggest that you open them all beforehand
to the approximate dimension you will need.
Applying WEST SYSTEM ® Epoxy
For laminations that are large and composed of many
pieces, you should organize the adhesive application
procedure so that it can progress quickly. Cover a bench
with polyethylene sheet and nail several sticks across it
to keep the laminations from touching the bench surface
when they are covered with adhesive and turned over.
Coat one surface of the lamination with an adhesive
mixture, roll the piece over on the strips, and coat the
opposite surface. <strong>The</strong> bottom and top pieces of the
lamination, of course, need coating on one surface only.
As you coat the pieces with adhesive, assemble them in
a neat stack in preparation for insertion in the form.
From the time that you begin, you will have about an
hour to apply the adhesive to all of the lamination
members, insert the members in the form, and apply
the clamping pressure. If the temperature is over 85°F
(29°C), you may not have this much time, even when
using a slow hardener. When laminating, adhesive
application usually requires the most time, but several
applicators working simultaneously can speed up this
operation.
We almost always use a high-density filler to make up
the adhesive mixture for laminating, determining the
thickness of this mixture according to the quality of our
wood. Rough sawn surfaces may require epoxy and
filler mixed to gap-filling, thick syrup consistency. With
Uneven clamping pressure
forces epoxy up and out of
the joint, causing distortion
or twist in the timber.
Clamps should be staggered
and tightened evenly.
Pads to protect wood
and distribute load.
Figure 11-7 Uneven clamping pressure forces epoxy out of
the joint, causing distortion or a twist in the timber. Clamps
should be placed in the middle of the laminate, spaced evenly
and tightened with consistent pressure.
sufficient clamping pressure, the epoxy used to laminate
well-planed stock will need little if any filler to guarantee
adequate adhesion.
Thoroughly stir your epoxy and filler and pour it into
a roller pan. Use a foam roller cut to the desired width
(the width of the lamination) to apply the adhesive to
your wood. Roll vigorously with downward pressure
to control the amount of epoxy on the bonding surface.
When a thicker adhesive mixture is rolled on the
surface, it will leave a thicker film, which is usually the
desired effect. A thinner adhesive mixture is easier to
control and you can roll it on the surface either in a
very thin film or in thicker quantities, as you wish.
Again, the quality of the laminating material will determine
how much epoxy you need to apply to the mating
surfaces.
When you have applied adhesive to all of the mating
surfaces (we always coat both mating surfaces), you are
ready to form the lamination. If you have already done
a dry run, the only thing you need to add is polyethylene,
which you can wrap around the lamination stack
to prevent it from becoming bonded to any of the form
members, clamps, or the floor. Be careful to prevent any
of this plastic from inadvertently becoming lodged
between some of the laminations, preventing a good
bond. <strong>The</strong>n apply clamping pressure, taking up the
clamps slowly as the adhesive squeezes out from