Quantcast Chapter 3. Wood Identification

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CHAPTER 3. WOOD IDENTIFICATION
Accurate identification of wood is an important component of the procurement process because of
the wide variation in physical and mechanical properties and value between species. A most ob-
vious application is the assurance that the species specified and paid for is received. This chapter
will describe features which can be used to identify wood species that are frequently used by the
U.S. Navy. Most utility poles and marine piling are either Douglas-fir or southern pine. Construc-
tion lumber and timbers are mostly southern pine, Douglas-fir, western hemlock or white fir. Oaks
and gums are commonly used in railroad ties. Pines and Douglas-fir are sometimes used for ties.
3.1 SPECIES SEPARATION. The identification of wood is a science and art. This section discus-
ses the gross characteristics which can be used to separate common species. Only a few species are
discussed, and the use of gross characteristics is by no means foolproof. These characteristics are
summarized in Table 3-1. For accurate determination, professional help should be consulted.
The first step in wood identification is the separation of the softwoods from the hardwoods. The dif-
ferences are discussed in Chapter 2. Softwoods have a more uniform, simpler cell structure than the
hardwoods. The two groups are seldom mixed in a shipment.
Figure 3-1 shows flat gram samples of four major softwoods: Douglas-fir, southern yellow pine,
western hemlock, and white fir. Douglas-fir and southern yellow pine both have a coarse gram pat-
tern which is caused by the abrupt transition between earlywood and latewood (Figures 2-1 and
2-2). Douglas-fir is predominately heartwood and has an orange-red to red or sometimes yellowish
color with a very distinctive resinous odor when freshly cut. Southern yellow pine, by contrast, is
predominately light colored sapwood. Some larger pieces, or those cut from the very center of the
tree, will have heartwood similar in color to that of Douglas-fir. Both species are moderately heavy.
Resin canals are present in both species, but they are more pronounced and common in pine and ap-
pear as white streaks in the latewood (Figure 2-2).
Western hemlock and white fir, by contrast, have a more uniform gram pattern which does not show
wide variations between earlywood and latewood. The heartwood of hemlock is light reddish-
brown with a purplish cast, especially in the summerwood bands, as compared to white fir which is
nearly white to pale reddish-brown. Both species lack resin canals, and are lighter in weight than
Douglas-fir and southern yellow pine.
Figure 3-2 shows flat gram samples of four major hardwoods; white oak, red oak, sweetgum and
black gum. White and red oak are both ring porous woods, and thus have a very distinctive coarse
gram pattern on the flat surface. Red oak is usually coarser textured than white because it is often
faster growing and does not have its pores or vessels plugged with tyloses. Also, on a clean cut end
grain surface, the pores of red oak appear open and those of white oak are closed by tyloses. White
oak heartwood is light to dark brown, while red oak has a distinctive pinkish or pale reddish cast.
Both woods have distinctive rays (Figure 2-4), are straight grained and heavy in weight.
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