CURRENT LITERATURE 



The Deterioration of Lumber. By M. B. Pratt. Bulletin 252, 

 Agricultural Experiment Station. Berkeley, Cal. 1915. Pp. 20, 



This bulletin gives the results of a study carried on in the yards 

 of a lumber company in the northern Sierra Nevadas of Cali- 

 fornia to determine the amount and causes of deterioration 

 between sawing and shipping. The species concerned were Sugar 

 pine, Western Yellow pine, and Douglas fir. The loss due to 

 depreciation in grade was found to be greater than generally 

 imagined, and was especially high in the case of Sugar pine. 



The depreciation in the case of air-seasoned stock was due to 

 blue stain, brown stain, check and warp, pitch, and the mechanical 

 defects resulting from the handling. Blue stain was found to be 

 the most serious cause of depreciation, being especially prevalent 

 in the case of piles put up in the fall. Brown stain, due to a 

 chemical reaction in the green wood and not to fungi, appeared 

 generally as a band between heartwood and sapwood, and often 

 was not discernible until the lumber was surfaced. It, however, 

 does not occur with Western Yellow pine. Both stains developed 

 most widely in the case of green sap lumber piled during hot, 

 humid weather. 



In the case of air-seasoned Sugar pine, there were tallied 

 40,000, 50,000, and 225,000 feet of fall, spring and summer 

 piling, respectively. The deterioration of the upper grades aver- 

 aged 70, 38, and 16 per cent, respectively, and the monetary loss 

 $12, $5, and $2.50 per thousand feet. 



As regards kiln-drying, the study showed that in this vicinity it 

 paid to follow this procedure for all of the upper grades of 

 Western Yellow pine and Douglas fir, both checking badly in 

 this vicinity with air-seasoning. In the case of Sugar pine, 

 however, there is so much "kiln-burn" that many operators do 

 not attempt it ; in surfaced lumber this cannot be told from 

 brown stain. The system of kiln-drying Sugar pine has usually 

 been that of keeping a low, steady temperature during the entire 

 drying period. An experiment by the author with 14,000 feet of 

 Sugar pine, treating it like Western Yellow pine, starting at 

 ISO** and raising it to 180°, showed much less "kiln-bum" than 

 under the low-heat system; the depreciation was less than air- 



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