THE SUITABILITY OF AMERICAN WOODS FOR PAPER PULP 47 
By Sulphate Process 
Reduces readily. 
Unbleached pulp: Soft and long fibered; required careful beating to develop 
satisfactory strength. 
Yields: 50 to 55 per cent of strong pulp, 35 to 40 per cent of pulp for bleaching. 
Bleach required: More than 25 per cent. 
Uses to which pulp is suited: Kraft wrapping papers and fiber board. 
By Mechanical Process 
Not suited to ground-wood production because of color. 
Redwood (Sequoia sempervirens) 
Other names in use. — Sequoia, California redwood, and coast redwood. 
Range. — From the southern borders of Oregon southward in the Pacific coast 
region 20 to 30 miles inland) to about 100 miles south of San Francisco. 
Oven-dry weight of the wood per cubic foot, grean volume, — 23 pounds. 
Fiber length. — 5.5 mm. 
By Sulphite Process 
Reduces readily but unevenly. 
Unbleached pulp: Fairly strong but brash, shivy, dark in color, and practically 
impossible to bleach. 
Yields: About 50 per cent. 
Uses to which pulp is suited: Low-grade wrapping papers. 
By Sulphate Process 
Reduces readily. 
Unbleached pulp: Fairly strong; fibers very long but soft and tender. Best 
results are obtained when chips are leached before cooking and 10 to 20 per cent 
of their weight extracted as a tanninlike dark red coloring substance. 
Yields: 35 to 40 per cent. 
Bleach required: More than 30 per cent, even when yield is reduced to 30 per 
cent. 
Uses to which pulp is suited: No. 2 kraft wrapping paper; with very careful 
beating, possibly No. 1 kraft. 
Both the specific gravity of the wood and the percentage yield by weight are 
low and combine to reduce the yield per cord below that of the coniferous woods 
generally pulped. 
By Mechanical Process 
Wood too dark for production of satisfactory pulp. 
5. HARDWOODS— DIFFUSE-POROUS 
Possible uses: Reference is directed to page 20 for a discussion of the uses of 
hardwood pulps as a group. Individual species differ as to the ease or difficulty 
with which pulps of satisfactory quality can be produced rather than as to specific 
uses for which they may be suited. Therefore no discussion of specific uses of 
pulps from the individual species will be attempted in the summaries. 
Sulphate process: Practically all American hardwoods can be pulped by the 
sulphate process as readily as by the soda process. The sulphate pulps usually 
bleach with less bleaching powder than soda pulps; otherwise the two classes 
show practically no difference in quality. The soda process, however, since it 
was established earlier than the sulphate and operates with greater freedom from 
offensive odors, has remained almost without challenge for the pulping of hard- 
woods. Therefore the sulphate process will be referred to only incidentally in 
this section. 
Aspen (Populus tremuloides) 
Other names in use. — Quaking asp, American aspen, aspen leaf, white poplar, 
trembling poplar, American poplar, poplar, popple, trembling aspen, and quak- 
ing aspen. 
Range. — Southern Labrador to Hudson Bay (southern shores) and northwest- 
ward to the Mackenzie River (near mouth); southward through Northeastern 
