166 



FOREST PRODUCTS 



The question of the effect of turpentining on the strength and dura- 

 bility of lumber and timbers has long been a debated subject. Investi- 

 gations have proven that it has practically no deleterious effect of this 

 kind; in fact, bled timber is more durable than " round " or unbled tim- 

 ber, owing to the increased presence of resin. However, on account of 

 the discrimination in the lumber grading rules against excessively resinous 

 lumber and the fact that the wood back of the faces on turpentined timber 



Photograph by U. S. Forest Service. 



FIG. 43. Cutting a " box " in the base of a longleaf pine for the collection of resin as it 



exudes after each chipping. 



is generally heavily filled with resin to a depth of % to i in., the propor- 

 tion of high-grade lumber contained in " round " or unbled timber is 

 somewhat greater than that cut from turpentined or bled timber. This 

 condition is minimized to a large extent by slabbing a butt log containing 

 a turpentined " face " at the saw-mill, in order to remove all of the wood 

 having a high resin content. 



