sitka spruce: uses, growth, management. 7 



Because of its light weight, combined with strength and tough- 

 ness, Sitka spruce is the most desirable and most generally used wood 

 for such airplane parts as wing beams, struts, longerons, ribs, and 

 plywood parts. Although red, white, and Sitka spruce do not differ 

 greatly in strength properties, the last species, on account of its 

 greater size and consequently its greater proportion of clear lumber, 

 is a more important source of aircraft material than the other two. 

 Because of this and the relatively large supplies of virgin timber still 

 remaining, Sitka spruce will probably for many years be a very im- 

 portant species in the aircraft industry, notwithstanding the fact 

 that the supply is far from the centers of manufacture. 



Because of the resonant quality of the wood, its even structure, the 

 absence of vessels, the extremely fine and regularly distributed medul- 

 lary rays, and the straight and long fibers, spruce generally is con- 

 sidered to be the best wood for piano sounding-boards, as well as for 

 musical instruments generally. Sitka spruce yields a large propor- 

 tion of clear lumber and wood of selected quality for this purpose, 

 but its rapid growth tends to lessen the resonant quality in compari- 

 son with the slower growing eastern species. 



Th,e wood is not durable in contact with the soil or when exposed to 

 weather. It is less suitable for piling in salt water than are other 

 species, because of its greater susceptibility to the ravages of the 

 teredo, which may destroy it in one or two years. 



For the manufacture of white paper pulp by either the mechanical 

 or the chemical process, spruce is the leading wood used. It is soft, 

 white, and nonresinous, and its fibers are longer, more flexible, and 

 stronger than those of most woods. Containing a maximum percent- 

 age of cellulose, it gives a high yield by the chemical process. Al- 

 though there are several species of spruce, no marked difference is 

 noted in the pulps manufactured from them. A comparison of the 

 character and uses of the pulp made from Sitka spruce with that 

 made from white spruce, a wood that can be considered standard for 

 pulping by the sulphite, sulphate, and mechanical processes, indicates 

 do practical difference. 



Because of the long distance to the large paper markets of the East, 

 the utilization of Sitka spruce for paper manufacture, is relatively 

 small. Of the domestic spruce consumption in the United States in 

 1918 for the manufacture of paper, 35,385 cords, or 1.6 per cent, was 

 Sitka spruce from the forests of Washington and Oregon. British 

 Columbia utilizes about half as much Sitka spruce for this purpose 

 as do the Studs of Oregon and Washington. Other species, includ- 

 ing western hemlock, white fir, cottonwood, and Douglas fir, are util- 

 ized on the Pacific coast in I he tnanu fad ure of pulp, but 8i1 ka spruce 

 represents about Lfi per cent of the total. 



