6 BULLETIN 1437, U. S. DEPARTMENT OF AGRICULTURE 
Red alder has a straight, fine, uniform grain, the narrow bands of 
summer wood appearing only as fine lines in a radial section. The 
wood has no definite figure, but sometimes the lumber shows streaks 
running in a vertical direction, known as " pith-ray flecks." These 
streaks are caused by the larva or grubs of certain insects that live 
in the cambium during the growing season. 2 They are not peculiar 
to alder ; similar flecks are found in birch, cherry, and a number o 
other woods. 
If properly cared for, red alder does not warp, check, shrink, or 
swell appreciably in place. It turns well and takes a fair polish. 
It also takes glue, paint, and enamel well, and makes an excellent 
imitation mahogany or walnut when stained. 
STRUCTURE AND IDENTIFICATION 
In red alder the pores are comparatively small, being invisible or 
barely visible without magnification. They are fairly uniform in 
size and evenly distributed, except that they are often slightly fewer 
in the extreme outer portion of each yearly growth — a condition 
which helps to mark the otherwise inconspicuous rings. The fibers 
are evenly distributed among the pores. (Fig. 2, A-3.) Pitch 
flecks may or may not be present. 
The medullary rays are mostly one cell wide, rarely two cells. 
Occasionally they combine to form compound rays, very distinct 
on the end grain and more or less so on longitudinal surfaces. 
Sometimes these compound rays contain dark coloring matter and 
are then plainly visible on the faces of veneer or dressed lumber. 
The transverse spacing between the compound rays as seen on the 
end grain is very irregular, varying from less than one-sixteenth of 
an inch to over 1 inch. These compound rays are the most distinctive 
structural feature of alder wood. (Fig. 2, A-2.) 
Seasoned red alder can easily be distinguished from other western 
hardwoods, except cottonwood, by its relatively light weight. It 
can be distinguished from cottonwood by its light reddish brown 
color and compound rays. 
PHYSICAL AND MECHANICAL PROPERTIES 
Red-alder timber is moderately light in weight, even grained and 
soft in texture, and has low strength values in comparison with 
" strong " woods. Compared on a basis of density or weight, it has 
nearly average values for most of its properties except that it has 
greater stiffness than the average. In the classification of woods by 
the Forest Products Laboratory of the Forest Service, according to 
the results of tests for each of six physical and mechanical proper- 
ties, red alder is classified as follows : 
PROPERTY CLASSIFICATION 
Density or weight. Moderately light. 
Strength as a beam or post. Moderately weak. 
Hardness. Moderately soft. 
Shock-resisting ability. Moderately poor. 
Stiffness. Moderately stiff. 
Shrinkage. Very moderate. 
2 Brown, H. P., Pith-ray Flecks in Wood. U. S. Dept. Agr., Forest Serv. Circ. 215, 
15 pp., illus. 1913. 
