WOOD EXPLORER
fdmonline.com
Gene Wengert
wooddoc@uwalumni.com
A fine, even-grained wood:
Eastern spruce
There are five major spruces in
North America, with three of
them growing in the eastern
half of the USA and Canada. These
three, collectively called eastern
spruce, are red spruce (Picea rubens),
white spruce (P. glauca) and black
spruce (P. mariana). Red spruce is
found primarily in New England, the
Appalachians and eastern Canada,
while white and black spruce is found
in the Great Lakes, New England and
eastern Canada. The wood of these
Processing suggestions and characteristics
Density. The three spruces have a density
of approximately 27 pounds per cubic foot
at 7 percent MC. This is one of the lightest-weight species in North America.
change, and about 1 percent size change
across the rings (radially) for each 10
percent MC change.
Drying. The spruces dry easily with few
drying defects. If logs or green lumber are
stored in warm weather, blue stain in the
sapwood is common.
Shrinkage in drying is 6 percent.
Final moisture contents for the spruces
should be between 7. 5 to 9 percent MC. As
with most softwood species, higher MCs are
desired, because excessively dry wood will
develop torn grain and may require increased
glue spread to avoid a starved joint. On the
other hand, wood much over 9 percent MC
will shrink as it dries to its in-use MC and may
develop some shrinkage defects.
Strength. Spruces are medium in strength
and stiffness. The bending strength (MOR)
averages 10,800 psi for red and black and
a little lower for white. Hardness averages
500 pounds. Stiffness (MOE) averages
1. 6 million psi in red and black, with white
being 1. 43 million psi.
Gluing and machining. The spruces
machine very easily, with few defects
except around the knots (typical cross-grain
defects). Gluing is excellent. The softness
means that the wood is quite forgiving if
gluing conditions are not perfect.
Stability. The spruces are subject to
minimal size changes when the MC
changes — about 1 percent size change
running across the grain parallel to the
rings (tangentially) for each 5 percent MC
Color and grain. The grain of the
spruces is straight, fine and uniform in
texture. The wood is pale white in color,
with the sapwood and heartwood being
indistinguishable most of the time. The
wood has no appreciable odor when dry.
three spruces is impossible to separate
visually once sawn into lumber. The
properties of the three are also essentially identical.
Eastern spruce trees are usually not
very large (seldom over 2 feet in diameter) and the lumber they produce
often has many very small knots. The
needles have been used for producing
beer and tea. The roots were used by
Native Americans for weaving baskets.
The sap was reportedly used to develop
chewing gum.
Spruce is known for its high
strength compared to its weight. But
the abundance of other softwood
species with clearer wood in much of
its growing area resulted in limited
harvesting and manufacturing of
eastern spruce lumber in the past. In
Colonial times, the wood was used
for mast and spars; this use continues
today for small sailing boats. Eastern
spruce has been used and still is used
for piano sounding boards, violins
and other musical instruments due
to its excellent resonance properties.
However, today, pulpwood is probably its number one use, followed
by construction lumber, especially
2 x 4s and 2 x 6s, much of which is
imported from Canada and is sold
under the species grouping of SPF
lumber (spruce, pine, fir). Yet this
eastern spruce wood has potential for
use in furniture and cabinets. Its gluing, machining, stability and strength
properties are ideal for such uses.
Perhaps the only limiting factor is,
because of past history of usage and
processing into construction lumber;
that is, it is hard finding mills that will
saw 4/4 and know how to properly dry
such wood for furniture. ●
