The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 9 – Buying Wood 75
to slice wood thicker than 1 ⁄8" without checking and
shattering, but an 1 ⁄8" veneer limit doesn’t seem to be a
real disadvantage with smaller boats. Longer hulls of
50' or more can use thicker stock if it is available. In
these cases, the use of thin veneer involves increased
labor for extra laminations, and this may be a major
concern.
Commercial plywood is often used in laminating. <strong>The</strong>re
are many areas, as will be described in later chapters,
where it is a good, practical choice. Plywood has already
been laminated, so its dimensions are stable. It is readily
available. Thin plywood will not split as readily as
veneer when it is bent over tight curves, and it is easy
to prefinish, especially for interiors on stringer-frame
hulls. Plywood does, however, have some disadvantages.
It is expensive and does not have the potential
strength of veneer. At least one third of its grain runs at
right angles to the remainder of it, so some compromises
may be necessary when you arrange it on a hull.
Veneer and Plywood
Sophisticated manufacturing techniques are used to
make both veneer and plywood. It’s helpful to know
a little about these processes before buying either
material.
Veneers are thin sheets of wood, which can be of
various species and in a range of thicknesses. <strong>The</strong>y
are cut from logs in two different ways: by slicing
and, more frequently, by rotary cutting or peeling.
With the latter technique, the log is held on lathe-like
spindles and rotated while a knife peels off a continuous
ribbon of wood. Slice-cut veneers are made by
quartering a log and then slicing it repeatedly with a
straight knife as shown in Figure 9-2. In both processes,
the log is thoroughly soaked before cutting. Plywood is
made of dried veneers, bonded in plies or layers with
the grain of each layer at right angles to the grain of
the layers on either side of it. At least three plies of
veneer are used in a sheet of plywood.
Buying Veneer
Slice-cut veneers are preferable to rotary-cut veneers
for several reasons. Peeled veneers are very unstable:
their tangential cut results in maximum expansion and
contraction. Sliced veneers are more expensive, but they
Eighth log
moved down
onto the pre-heated
knife in veneer slicer.
Quarter log
milled to eighth
log then sent
to vats for
soaking.
Courtesy of J.M. Vaughn
Olympic Mfg. Co.
Figure 9-2 Manufacturing sequence in veneer slicing.
are more like vertical grain, quarter sawn lumber and
are very stable and unlikely to warp. <strong>The</strong>y have an
additional advantage in that they are available in longer
pieces. In general laminating, where limited clamping
pressure is used, sliced veneers are easier to hold in
place and require fewer staples.
Few lumberyards sell sliced veneers. In fact, so far
as we know, you will have to order veneers from the
companies that cut them. This sole source situation
works well for those who can use fairly large quantities
of veneer because manufacturers’ prices are usually low.
Sliced veneers are commonly sold by the square foot
(in 1985, 1,000 square feet of 1 ⁄8" cedar veneer cost $450)
and are shipped in flitches—bundles 1' to 18" wide.
Each flitch contains from 500 to 1,000 square feet of
veneer. Smaller quantities, as might be needed for a
dinghy, can be more expensive to buy and ship.
Sliced veneers up to 17' long are usually available, but
12' pieces are adequate for most laminating. Pieces less
than 12' long can be used less wastefully in smaller
boats. Widths are random in all lengths, but generally
range between 6" and 12". As we explain in later