For the mill that produces a quantity of dead lumber, some experimentation will 

 probably be necessary to determine the optimum drying conditions. The white pine study 

 mill was equipped with a high temperature kiln. The mill has settled on the practice 

 of using an initial dry bulb temperature of 190° F with a wet bulb depression of 30° F. 

 During the winter months when the logs and lumber are high in moisture content or are 

 frozen, these drying conditions are maintained for 24 hours. During the summer months, 

 and especially if there is a delay between piling and drying, the kiln time is reduced 

 to 12 hours, but the same drying conditions are used. Whether these are optimum drying 

 conditions is not known, but the mill reports no planer split or other drying degrade 

 as a result of these schedules. 



LODGEPOLE PINE 



Methods 



The second study, on lodgepole pine, was conducted at a mill in southeastern Idaho. 

 This mill obtains most of its logs from the Targhee National Forest which has been the 

 site of an epidemic infestation by the mountain pine beetle, Dendroctonus ponderosae 

 (Hopk.). Over the past two decades, this insect has been responsible for killing an 

 estimated 2 billion board feet of lodgepole pine timber on this Forest. Some of this 

 dead timber has been purchased by the study mill. 



The mill is equipped with a small headrig for breaking down logs over 14 inches in 

 diameter and a quad-band mill for sawing logs under 14 inches. Edgers are used to cut 

 the cants into 2 by 4's. Only studs and a few 1 by 4 sideboards are produced. This 

 limited number of products eliminates the necessity for a green chain, instead the 

 lumber is stickered and piled on kiln trucks for drying at the back end of the mill. 



For this study a sufficient number of dead logs were processed through the mill to 

 produce two kiln trucks of studs. The logs were debarked, cut to length, and fed into 

 the mill. A measuring station was established at the midpoint of the chain carrying 

 the studs to the stacker. At this station, the moisture content of a random sample of 

 the studs was determined using the same moisture meter used in the earlier study. The 

 speed of the chain and the desire to sample as many studs as possible precluded the use 

 of all the meter scales; instead only the 12 to 22 percent moisture content scale was 

 used. Those studs having a moisture content greater than 22 percent were recorded as 

 having the scale maximum. In addition, 22 studs were pulled from the chain for destruc- 

 tive sampling. At the completion of the mill run a 2-foot-long piece was cut from the 

 center of these studs and saved for later preparation of test sections. 



Three test sections, approximately 1 inch long were cut from near the center of 

 each piece as in the earlier study (fig. 1). These sections, again labeled A, B, and 

 C, were used for determining moisture content, moisture distribution, and drying stress. 



After determining their moisture content, the studs were piled for drying in the 

 automatic stacker. The two kiln trucks of dead tree studs accumulated during the study 

 were identified and dried in a single kiln charge along with six trucks of green studs. 



S 



