THE AIR SEASONING OF WESTERN SOFTWOOD LUMBER 55 
of the year and are responsible for an inactive drying season extend- 
ing from about October 1 to April 30. June, July, and August are 
the most favorable drying months, but rarely do temperature and 
humidity during these months reach such extremes as to cause ex- 
cessively rapid drying. 
Douglas fir lumber constitutes 80 per cent of the output of this 
region. Next in volume is western hemlock, which constitutes 10 
per cent of the total. Sitka spruce and western red cedar together 
account for 7 per cent. Other softwoods, including the true firs 
Beer] aacr oR 
COMPRBPATIVE MAONTYILY WEATHER CONOATIONS 
PER CLT 
ALLATIVE 
AILS AA/O/7 
BS GO 
TEMPLEATUCE 
Ze 





ACTIVE DRYING SEASON 









Behe . 
—— AELATIVE HUM/D/ITY-MONTHLY AVERAGE 5 OR BPA. 
sm == TEMPERATURE -/4EAN MONTHLY 



MWEKAGE PRYING PLRODS FoR G0CK 1 LUFLOLNT NUONTHE SAWERAGCGE WUPIBER OF LAKE 
TO RESCH N\4 s 
2 LE NG \ o0| 60| s6| 26 | 26 | 20 | 20| |peco|eo| a0 
MO/STURE yy 
CONTENT '\74 \ ya\ 9o\ G8 \ 45\ BE \ 30 | 30 \ 25|\L9O|\200\/70\20 
7 a es Pen 
APLROUMATE MUSTURE CONTENT OF THOR} G pL Y ARDY STOCK BY MONTHS 
PER CENT 
AVERAGE PCKUP OF MUISTURE By EVAR STOCK AT DIFFERENT SEASO/YS 
eee ee | Fe) i se) |- | | |? 28 
Fic. 10.—Graphic air-seasoning chart for the Douglas fir region 












70 REACH 
18 FER CLT 
VVOVET URE 
CONTENT 









and Port Orford cedar, make up less than 1 per cent of the cut. 
(Table 1.) 
Certain characteristics of these species bear on the air-seasoning 
practice of the region. Little or no consideration has to be given 
to blue stain, either in the seasoning yard or in green shipments 
by rail or water. Douglas fir, western red cedar, and Sitka spruce 
are species of relatively low moisture content. Western hemlock is 
not excessively high. 
In considering the extent to which air seasoning is practiced in the 
Douglas fir region, markets and the size of the stock cut must be 
taken into account. Of the total annual production in the region, 
probably a little less than half is shipped to domestic and foreign 
