UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 343 



Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



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Washington, D. C. 



PROFESSIONAL PAPER 



April 26, 1916 



GROUND-WOOD PULP. 



By J. H. Thickens, Chemical Engineer in Forest Products, and G. C. McNaughton, 

 Engineer in Forest Products. 



CONTENTS. 



Object of the bulletin 1 



Present status of the ground-wood industry. 2 



Present methods of manufacture 6 



Parti- 

 Equipment used in the experiments 7 



Methods employed in experimental tests . 9 



E ffect of preliminary treatment of spruce . 1 1 



Part I— Contd. 



The effect of variable grinding conditions . 17 

 Part II— 



Experimental and commercial tests on 34 



various woods 67 



Appendix A 



Appendix B 151 



OBJECT OF THE BULLETIN. 



This bulletin presents the results of tests on (a) the grinding of 

 steamed or cooked spruce for mechanical pulp and (b) the results 

 of tests on a number of American woods to determine their suit- 

 ability as substitutes for spruce in the manufacture of ground-wood 

 pulp. 1 If the price of news-print paper is to be kept at a reasonable 

 figure, more efficient methods of converting spruce into pulp must 

 be developed or else a cheaper wood substituted for the former. 

 The results of experiments meant to develop greater efficiency in 

 the grinding of uncooked spruce have already been presented in 

 Forest Service Bulletin 127, "The Grinding of Spruce for Mechanical 

 Pulp." That bulletin also discusses the influence of the many 



1 Acknowledgment is made to Mr. C P. Winslow, Mr. Henry E . Surface, and Mr. S. D. Wells, engineers 

 in forest products, and to Mr. S. E. Lunak, assistant chemist in forest products, Forest Service, for aid in 

 the preparation of this report. Acknowledgment is also due Messrs. G. F. Steele, W. G. McNaughton, 

 and L. M. Alexander, of the Nekoosa-Edwards Paper Co., and Mr. D. C. Everest, of the Marathon Paper 

 Mills Co., for assistance rendered during the tests; also to Mr. C W. Knapp, of the St. Louis Republic, 

 and to Messrs. P. W. Schaeffer and E. D. De Witt, of the New York Herald, for providing the presses 

 upon which the experimental papers were tried out. The maps in this bulletin showing the range of 

 the various tree species were prepared in the Forest Service by Mr. William H. Lamb, assisted by Miss 

 Georgia Wharton. 



Note. — This bulletin contains valuable information as to the use of various species of wood in the manu- 

 facture of paper and is of interest to manufacturers and users of paper. 

 14852°— Bull. 343—16 1 



