UTILIZATION OF BLACK WALNUT. O 
purplish brown. The annual rings of growth are usually broad and 
are marked off from each other by the presence of many pores at 
the beginning and a somewhat dense growth at the end of each 
annual ring*, as well as by a fine light-colored line between adjacent 
rings. This contrast between the growth rings is especially marked 
on tangential cuts and gives a somewhat coarse figure to the wood. 
The pores are compartively large and in cross sections easily visible 
to the naked eye ; they appear as fine dark and generally short lines 
over the entire longitudinal surface. Figured wood is in demand for 
different kinds of finish. Its handsome effect is often produced by 
dark-colored streaks or alternate stripes of lighter and darker 
shades. The striped figure in quartered stock is caused by the 
alternate light and dark shades of the growth rings. Another kind 
of figure is that formed by the wavy or curly grain which is found 
near a knot or other defect. Abnormal or irregular growths, crooks, 
forks, and twists produce a special figure in the wood. Highly 
figured walnut, with a great variety of design, is cut from the walnut 
burl — an abnormal growth of wood tissue. 
PHYSICAL AND MECHANICAL PROPERTIES. 
Black-walnut wood is heavy, hard, strong, and stiff. It is easy 
to split, has good shock-resisting ability, shrinks moderately in 
seasoning, is susceptible of a good polish, and takes paint, stain, and 
other finishes exceedingly well, 
The results of certain Forest Service experiments on black walnut 
tested green are shown in Table 1 in comparison with oak, The 
strength values of the green wood are considered the best basis for 
comparison. Yv r alnut compares still more favorably with oak when 
their dry weights are taken into consideration. For instance, black 
walnut, Avhich has a dry weight of 85 per cent of the dry weight of 
oak, has shock-resisting ability 27 per cent greater and strength 
in bending 14 per cent greater than that of oak. As to strength in 
( ompression parallel to the grain, walnut rates 21 per cent higher, 
and in stiffness 14 per cent more. The shearing strength of walnut 
is only slightly less than that of oak. The hardness values of wal- 
nut and oak are in the same proportion to each other as their specific 
gravities — 85 per cent. As to strength in compression perpendicular 
to grain, walnut has a lower value than oak. The shrinkage of 
black walnut in volume is less than that of oak, which is about 16 
per cent. Shrinkage in the radial direction is about the same in 
both woods; but in the tangential direction the shrinkage of black 
walnut is less than that of oak. The ratio of radial to tangential 
shrinkage is much less in black walnut than in oak. In weight, and 
likewise in dimension, walnut changes slowly with changes in 
atmospheric conditions. 
