44 DEPARTMENT BULLETIN 1425, U. S. DEPT. OF AGRICULTURE 
upon the air seasoning of lumber. Figure 7, although based on 
weather data obtained only in western Montana, northern Idaho, and 
eastern Washington, illustrates characteristic features of the Inland 
Empire. Two well-defined periods are indicated—an active drying 
season which ordinarily extends from April 15 to October 10, and a 
much less favorable period of drying during the remainder of the 
year. Particularly in the spring and fall, warm days with relatively 
high humidities are common. Such conditions are ideal for blue- 
stain development. During the summer months periods of extremely 
low humidity cause excessively rapid drying. 
The kinds of lumber produced, of course, influence the seasoning 
practice. Western yellow pine, now designated pondosa pine by 
| Aur racroR yan yes yrarlaceyia ine Wel S22) 067 WO 0E| 
| 
COMPARATIVE MONTHLY WEATHER CONDITIONS 
PER CENT | TO 
PELATIVE 
AHlUMIDOI TY 
OP 
TE/IPERATURE 
oc 

T | I I | 
ACTIVE DRYING SEASON 
7 SS 
Pe wy 





~ 

= 








x 
RELATIVE HU/MIDITY-PIONTHLY AVERAGEEPNIS. 
0° <== TEMPERATURE - MONTHLY AVERAGE 4PM. N. 








AVERACE LRIIWG FLERIODS Fie ST0LK PULLD MM LUEFERLAT (UWTBE 70 REACH IE PE CENT WIEST COWIEWT 
acoseenncrvere yz0\a0 [eo oo] 20 | ze| 20) 20 | 20 
ADR OUNMATE JAOVSTLIPE CONTENT OF THOROL CGAL APLC STOCK LY MONTHS 
PER CENT 
I \WCOlSTWE CONTENT | Zor| ZO#\/B+\ 7S | (4 \ (2 \/ZA\ IB \ 4 | LS#\ZO4\LOF 
MVERAGLE PICKLP OF UZUISTURL BR YARD SIOCK AT LDI-FERENT SEASONS 
TIE 




Fic. 7.—Graphic air-seasoning chart for the Inland Empire 
the industry of the Inland Empire, constitutes nearly half of the 
annual cut. The western white pine, or Idaho white pine, is next 
in importance, although the combined production of larch-fir exceeds 
that of the white pine. White fir is also cut in appreciable volume. 
Western red cedar, Engelmann spruce, western hemlock, and lodge- 
pole pine are of comparatively minor commercial importance. 
(Table 1.) | 
Certain manufacturing practices characteristic of this territory 
have a real bearing on the air-seasoning problem. The region is 
primarily a “board” producer, a very large proportion of the cut 
being in the form of 4/4, or 1-inch stock. Only a small quantity 
of pine is cut heavier than 6/4. Larch-fir goes into 2-inch and 
thicker products to a greater extent than any of the other 
regional species. Considerable 6/4 white fir is now cut. Most of 

