
92 DEPARTMENT BULLETIN 1425, U.S. DEPT, OF AGRICULTURE 
SEGREGATION OF STOCK FOR PILING 
The sorting of green lumber by species, grades, and sizes follows 
to some extent a general standard in each region. It is of necessity, 
however, primarily an individual plant problem because of the many 
considerations involved. Quantity production of different items, 
sorting and yarding facilities available, trade customs and demands, 
and requirements for proper seasoning must each be considered in 
its proper relation to the others. Of these, the items produced in 
quantity and the yard facilities ordinarily vary most as between 
plants. Seasoning requirements, although of real moment, are rarely 
given their proper weight in the choice of a sorting practice. 
IMPORTANCE IN AIR SEASONING 
Proper stock segregation is an essential element of effective air- 
seasoning practice. Individual species usually have distinct drying 
requirements and accordingly should be piled separately. This is 
also largely true for different grades of the same wood, although 
some of these may be segregated for drying by natural groups. The 
soundness of such methods can best be demonstrated by a specific 
example. : 
Western yellow pine and white fir, species commonly produced at 
the same plant, need very different seasoning treatment. Western 
yellow pine is more susceptible to blue-stain depreciation than any 
other western species and therefore requires a method of pile con- 
struction which will favor fast drying and thus tend to retard 
development of the stain organism. White fir, on the other hand, 
is not subject to stain depreciation but is much more liable to check 
if seasoned rapidly. In the select grades of western yellow pine 
sapwood is present to a greater extent than in the common grades, 
and the select grades are therefore more susceptible to blue stain. 
~The common grades, however, because of greater hability to knot 
defects, call for slower drying. 
Segregation of stock by thickness is almost a necessity because of 
the difficulties incident to piling the unsorted lumber. With lumber 
of random thickness it is practically impossible to obtain an even 
bearing surface for the crossers and thus to avoid warped stock and 
poor horizontal circulation. Another serious objection is that the 
drying period for the entire pile is dependent upon the time required 
by the thickest pieces. For example, 4/4 stock requires but 50 to 80 
per cent of the time necessary for 8/4 stock to reach the air-dry con- 
dition, the ratio varying with different species, grades, seasons of 
years, and general drying conditions. 
For thorough seasoning, width segregation is of real value. The 
vertical air circulation in the lumber pile should be assisted in every 
way practicable by the method of pile construction. Unobstructed 
vertical channels throughout the width of the pile are therefore very 
desirable, and it is only by piling separate widths that uniform verti- 
cal flues extending from top to bottom of the pile between each tier 
of boards are possible. 
Segregated lengths are also an advantage in piling for air season- 
ing. With each length separated it is more readily possible to em- 

