Forestry Kaimin, 1958

Composite drying-rate charts were then Results and Discussions drawn from the individual drying-rate curves. Results of the drying tests were tabulated, as Since the charts are drawn from assumed aver well as the moisture content and specific grav age initial moisture contents, representative fig ity of the logs from which the veneer was cut. ures of 35 percent for heartwood and 100 per Because of limited space, the tables are not cent for sapwood were selected as the average shown. However, several interesting observa initial moisture contents. The desired final tions were made from the data in the tables. moisture contents chosen were 4, 6, and 10 per The most important of these was the dif cent. To draw the drying-rate charts, drying- ference in moisture content between the heart rate curves of veneer dried at two different tem p wood and sapwood in the green veneer and in eratures were needed. In this study, tempera the log. The moisture content of the green tures of approximately 250° and 300° F. were heartwood veneer was, on the average, within used. Figure 2 illustrates the method employed. 1 percent of the moisture content of the heart Using the sapwood veneer to illustrate the pro wood in the log; however, green sapwood cedure, the charts were drawn in the follow ing veneer that was freshly cut averaged 14 per manner: cent lower than that of the log in moisture content, and in one case was as much as 27 From figure 1, the points were determined percent lower. There are several possible ex where the drying-rate curve intersected the 4 planations for this discrepancy. The most ob and 100 percent moisture content readings. vious is that since the sapwood has a higher The distance between these two points on the moisture content than the heartwood it might abscissa was then read as the required tim e in lose more moisture as it is handled between the drier. A point was then plotted on the chart, lathe and the drier. However, the following with the time in drier as the ordinate and the explanation may be more correct. It was ob average temperature in the drier as the absciss^. served that at the lathe a large volume of In like manner another point was plotted from water was squeezed from the sapwood because the veneer drying-rate curve of sapwood dried of the pressure applied by the nose bar; very at 250 F. Through these 2 points a straight little water was squeezed from the heartwood line was drawn to represent the drying rate for at this time. Apparently because of higher 1 /10-inch sapwood dried from an initial mois moisture content of the sapwood initially, it lost ture content of 100 percent to a final moisture over three times as much moisture as the heart content of 4 percent. Similar charts were then wood. drawn for heartwood dried to 4 percent and for In the first drying tests, it was found that the heartwood and sapwood dried to 6 and 10 per veneer was frequently being overdried to below cent. the desired 4 to 10 percent moisture range. It is assumed that one can select any drier This occurred because the drying schedules were temperature between 220 and 360 F. and, first set up to approximate those commonly from the charts, read the time necessary to dry used in commercial drying. The final schedules to the desired moisture content of 4, 6 or 10 arrived at were much faster than commercial percent. To check the accuracy of the charts, it times. This would seem to indicate that com was arbitrarily decided to dry sapwood at 280 mercially dried Douglas-fir is generally over- F. to 6 percent moisture content and heartwood dried. It must be added, however, that to dry at 285° F. to 4 percent. From the charts, the most of the veneer to a moisture content range times in the drier were determ ined to be 14 of 4 to 10 percent in the short times used in this minutes for sapwood and 7 minutes for heart study may allow wet spots to remain in some wood. of the veneer. Such wet spots are unacceptable commercially, where no conditioning is done Check tests were made on additional pieces of before gluing. veneer, dried on the indicated schedules. The average of 12 samples of sapwood showed a A problem that might complicate the use 51 percent moisture content after drying, and of the drying charts made in this study is the an equal number of heartwood samples averaged difficulty of accurately controlling the tempera 3.6 percent. ture of the drier. This was noticed especially 25 at the higher temperatures and when there was the curves were obtained by drying heartwood a heavy demand for steam pressure. It is ap and sapwood veneer at two different tempera parent that even greater diffi :ulty would be tures. From the drying-rate charts, times to dry encountered in large commercial driers than in 1 /10-inch Douglas-fir veneer to average mois the relatively small drier used in this study. ture contents of about 4, 6, and 10 percent can be estim ated for any drier tem perature between Sum m ary 220° and 360 F. A fter establishing the charts, Vener drying-rate charts were prepared for check tests were m ade by arbitrarily selecting 1 /10-inch Douglas-fir veneer. These charts tem peratures to dry heartwood to 4 percent were drawn from vener drying-rate curves. The moisture content and sapwood to 6 percent. At drying-rate curves illustrate the straight line the selected temperatures, the required drying drying relationship shown in earlier tests at times were estimated from the charts. The the Forest Products Laboratory/ The data for veneer thus dried came to an average moisture content that was within 1 percent of the de s p e c i e s D o i m l EH f i K s a p/ h e a r t S / T r o a t e S / 3 - ^ 7 THICKNESS 7SURER A JUKE 3 o 2 °F nNSEPKEP 5 )4 0 sired value: These results support the theory W - 2 4 X t /0-f M.R » _ £ 2 _ 2 - T / S '. 3 th at veneer drying-rate charts can be developed, along the lines outlined here, for any given condition of species, initial and final moisture content, veneer thickness, and drier temperature. SPECIES FiK B.C., INITIAL** /P C * . BATE J - /J - E 7 I V,* TIME FROM END OF DRYING CYCLE (MINUTES) M lij 2Si Figure 2.— Drying-rate chart for Douglas-fir veneer, 1/10 Figu.re 1.— A representative drying-rate curve for Doug- inch thick, showing effect of drier temperature on time las-fir sapwood veneer, 1/10 inch thick, dried at a temp required to dry to an average moisture content of 4 erature o f 302° F. percent. (M 113 251.) (M 113 250) 26 W inter Quarter 1958 27 Activities LOGGERS Gene De Bruin FORESTERS Lee Belau Art Hollowell Bob Swift Ron Stoleson Jim Vukonitch Glen Beckman Dick Gibson George Knapp Jerry Gruber Fred Ebel Arnold Joyce Ray Maidment SKI TEAM SWIMMING K en K eefe Gene De Bruin Jay Bertino Holt Quinn John Manz Priest La!{e De ndro Field Trip By O. B. HOWELL In February, all students in Dendrolgy make a 4- cabins accommodating 10 to 20 persons. There s day field trip to Priest Lake, Idaho. Here the climatic hot water, showers, and meals in the main lodge. zones intermingle at 3600 feet elevation. Snowshoeing is part of the trip. At this time of Priest Lake is nestled in the mountains and bene year, the snow varies from 3 to 7 ft. deep. All stu fits from 34 inches of annual rainfall. With this dents have their own snowshoes. amount of precipitation, hemlock, yew, white and Near Priest Lake is the USFS Experiment Station engelman spruce, white, ponderosa and lodgepole with a 40 acre aboretum. In acre blocks there are pine, grand, alpine, concolor and douglas fir, scopu- plantations of jack, black, pitch, brisltecone, red, larum and creeping jumpers, larch and western red ponderosa, lodgepole and jeffery pine, black, white, cedar are growing in a mixed company of poplar, blue and sitka spruce, balsam, concolor, grand, alpine aspen, maple and mountain ash. It is here one can firs, mountain, eastern and western hemlocks, plus see as many as ten kinds of trees in a 50 ft. radius. many varietal plots of douglas fir and junipers. Students are lodged at a swank summer resort in O. B. Howell setting the pace No one complained about the chow! 28 41 at Annual 3far?Ht?ra lull •-.V'T ; 29 Chief Push Ed Bloedel And A Good Time Was Had By All For 5 days and nights last January, the M.S.U. Field Flouse was alive with the sounds of pounding hammers, roaring chainsaws, straining muscles, earth shaking yells, lively music, and the tapping of the can can girls dancing feet— the reason?— Why the Montana Foresters were putting on the greatest social event on the University Campus! The theme for this year’s ball was "America’s Range Resource’.’ Following this theme, the decorations consisted of a complete "Wild West” western town along one side of the dance floor and 2000 Douglas Fir trees, cut dur ing the fall, around the rest of the floor. Dance series were announced by buf falo, cattle, and bronc riders, (the numbers branded on the animals sides) thundering across the length of the field house above the trees and band.

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