BULLETIN OF THE 



No. 80 



Contribution from the Forest Service, Henry S. Graves, Forester. 

 August 31, 1914. 



(PROFESSIONAL PAPER.) 



EFFECTS OF VARYING CERTAIN COOKING CONDI- 

 TIONS IN PRODUCING SODA PULP FROM ASPEN. 



By Henry E. Surface, 

 Engineer in Forest Products, Forest Products Laboratory. 



PURPOSE OF EXPERIMENTS. 



At the present time practically all of the soft, easy-bleaching pulps 

 used for the manufacture of high-class book, magazine, general print- 

 ing, and the cheaper writing papers are made by the soda process. 

 In England such pulps are produced from esparto (alfa, or Spanish 

 grass) ; in America, from the poplars and similar woods. Although 

 the soda process of wood-pulp manufacture is not employed commer- 

 cially to so great an extent in America as the sulphite and mechan- 

 ical processes, it is remarkably well adapted for producing pulp fibers 

 from any kind of wood or other fibrous vegetable material, no matter 

 how resistant to chemical attack it may be. For this reason it is 

 much used in the experimental work of the Forest Service. 



To insure that a wood has been subjected to the most favorable 

 cooking conditions it is necessary to cook it under many different 

 conditions produced by varying such factors as the amount and con- 

 centration of the cooking chemical and the duration and temperature 

 of cooking. While the general effect of using greater or less severity 

 of cooking is well recognized in mill practice, there has been almost 

 no available information on the quantitative effects of the individual 

 factors concerned nor on the limitations within which such effects 

 are exerted. Such meager information as may be found in the litera- 

 ture is widely scattered and is not strictly applicable to manufactur- 

 ing conditions. Notwithstanding modern improvements and the 

 general tendency toward more efficient operations in commercial 

 plants, the most economical production apparently is not being 

 attained by all of the soda-pulp mills. This is indicated by the fact 

 that some of them are using from 10 to 20 per cent more pulp wood, 

 from 50 to 100 per cent more chemicals, and from 10 to 40 per cent 



1 This paper presents detailed information of value in experimental work in the laboratory and in pro- 

 moting the efficiency of commercial paper-making plants employing the soda process. 



31091°— Bull. 80—14 -1 



