PRESSURE TREATMENT OF DEAD LODGEPOLE 



PINEFENCEPOSTS 



Procedure 



Thirty-nine posts from dead lodgepole pine trees were taken from a single national 

 forest in western Montana for use in this study. The same general procedure was 

 followed in preparing the posts for treatment as in the preceding study. Disks were 

 cut from both ends of each post and heartwood and sapwood specimens were cut from the 

 disks for determination of specific gravity and percent moisture content. The posts 

 were also cut to a uniform length, 6.5 ft (2.0 m) . 



The posts were next carried to a commercial wood- treating plant and all but five 

 of the posts were debarked. The posts were then weighed to the nearest 0.5 lb (0.23 

 kg). The post number, weight, and end diameter were marked on metal tags and fastened 

 to the respective post. Trams were used to transport the posts into the treating 

 cylinder and the study posts were loaded on the last tram to enter the cylinder 

 (fig. 2). 



Figure 2 . --Lodgepole pine study posts being loaded 

 on last charge tram car prior to treatment by 

 the pressure method. 



After the cylinder is loaded and sealed, the usual treating procedure is to draw 

 and maintain an initial vacuum of about 27 inches of mercury (9.83 kPa) for 30 min- 

 utes. At the completion of this interval, without releasing the vacuum, the cylinder 

 is filled with the preservative solution and a pressure of 100 lb per inch^ (689.48 

 kPa) is applied for 3 hours. The cylinder is then drained, the tram cars removed, and 

 the posts unloaded and bulk piled until sold. 



The preservative used is an unheated water solution, 1.50 to 1.75 percent of 

 fluorchrome arsenate phenol, type B (Osmosalts) . Sodium fluoride, sodium arsenate, 

 sodium dichromate, and dinitrophenol are the principal preservative compounds. 



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