


THE AIR SEASONING OF WESTERN SOFTWOOD LUMBER 
By 8. V. Futtaway, Jr., Formerly in Charge Office of Forest Products, Missoula, 
Mont., HERMAN M. JOHNSON, Assistant in Forest Products, Portland, Oreg., 
and C. L. HILL, im Charge Office of Forest Products, San Francisco, Calif., 
Forest Service 

CONTENTS 
Page Page 
PELE OGUCEION ais ee eee eer nai el PIL BO Lh a i) |) Aur-seasoning practice aasasceesnecee seen eee 13 
Important principles of wood drying and their May Ghavabatee nl OT se 13 
PEneralvap pl Cations we se ayaa 3 Segregation of stock for piling. _--________- 22 
Occurrence of moisture in wood__________- 3 IPile;constrUctione Bae Ou yee en Deena 23 
Movement of moisture in wood___________- 4 Summary of methods for improving drying 
Effect of humidity on drying______________ 5 EAC ECE ei a0 es Ch OI a a pe We 
Effect of temperature on drying__________- 6 | Regional air-seasoning problems and their solu- 
Effect of air circulation on drying_________- 6 GLO CU ta Wa Tn I icra aoe Norell el 43 
Conditions outside of the pile that influence Inland Empire pine region____-__-_---___-- 43 
AlTESCASO MIN Beane eh ee etd 6 California pine regions == ee 49 
Circulation of air within the pile__________ iG Riedwoodiregion eS ee 51 
Causes and control of stock depreciation... 9 Douglaswirregion= 2220 ee ee 54 
| INTRODUCTION 
_ A real need exists in the lumber industry for a concrete presen- 
tation of efficient air-seasoning methods for western softwood lum- 
_ ber, including a review of the general principles that govern the 
_ drying of wood and their application to yard drying. Air-seasoning 
losses in the West, both in quantity and quality of the product, 
can be reduced. The average drying time can be shortened, with 
a consequent faster overturn of stocks. Shipping weights can be 
lowered and final moisture-content requirements more nearly at- 
tained. Moreover, highly competitive conditions in industry make 
essential all practicable improvement and economy in lumber manu- 
facture, as well as a product of the highest possible utility and one 
that meets consumer requirements satisfactorily. 
The import of such considerations to the lumber industry of the 
West is evident in view of the fact that 35 per cent of the total 
annual cut in its four‘ principal producing regions is air seasoned, 
or approximately 4,500,000,000 board feet, at a rough valuation of 
$120,000,000. 


1 Douglas fir region of western Oregon and western Washington, “Inland Empire,” 
California pine region, and redwood region. 
1 
