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 hard, stiff, and has a high shock resistance. Because it lacks tyloses in its pores, it is extremely
porous and thus will accept preservative treatment.
The heartwood is grayish-brown with a distinctive reddish tint. The pores are open, and the outlines
of the larger pores are distinct. On smoothly cut end gram surfaces, the latewood pores can be readi-
ly seen when examined with a hand lens. The wood rays are 1/4 to 1 inch high along the gram and
can be seen without a hand lens (Figure 2-4). On end gram surfaces, rays appear as lighter colored
lines crossing the growth rings.
3.2.2.2 White Oak. The white oak group (Quercus sp.) includes white oak (Quer-
cus alba), chestnut oak (Q. prinus), post oak (Q. stellata), overcup oak (Q. lyrata), swamp chestnut
oak (Q. michauxii), bur oak (Q. macrocarpa), chinkapin oak (Q. muehlenbergii), swamp white oak
(Q. bicolor), and live oak (Q. virginiana). These species constitute the commercial white oaks and
grow east of a line from western Minnesota to western Texas. Some minor species are found in
Oregon, Washington, and California.
The white oaks are heavy woods, averaging 47 pounds per cubic foot, and are very hard, with a
specific gravity of 0.68 for white oak to 0.81 for live oak. Led by live oak, they rank high in
strength properties.
The pores of the heartwood, with the exception of chestnut oak, are plugged with tyloses--a froth-
like growth that makes the wood impervious to liquids. The heartwood is resistant to decay. White
oaks are above average in all machining operations except shaping.
The heartwood is grayish-brown. The outlines of the larger pores are indistinct except in chestnut
oak, which has open pores. On smooth cut, end grain surfaces, the latewood pores are not individual-
ly distinct. Wood rays are generally higher than in red oak, the larger ones ranging from 1/2 to 5 in-
ches in height along the gram. As in red oak, the rays appear lighter in color than the background
wood on end-grain surfaces and darker than the background wood on side-grain surfaces.
3.2.2.3 Sweetgum. Sweetgum (Liquidambar styraciflua) grows from south-
western Connecticut westward almost to Kansas and southward to eastern Texas and central
Florida. The commercial range in the United States is confined largely to the moist lands of the
lower Ohio and Mississippi basins and to the lowlands of the southeastern coast.
Sweetgum is a moderately heavy wood with an average weight of 36 pounds per cubic foot. The
wood is hard, with a specific gravity of 0.52, moderately strong when used as a beam or post,
moderately stiff, and has moderately high shock resistance.
Sweetgum has a very large shrinkage in drying, and the sapwood and heartwood require different
drying processes. The heartwood has low to moderate decay resistance. In nail-holding ability and
in ability to resist splitting by nails and screws, sweetgum is rated intermediate.
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