Practical Drying Techniques for Yellow-Poplar S-D-R Flitches

A preliminary study was conducted to determine what duration of steaming or high-temperature treatment would be required to relieve growth stresses in 7/4-inch-thick yellow-poplar flitches. Steaming times of 5, 10, 15, and 20 hours were tested and it was found that the average stress and its standard deviation decreased at 15 hours. From this data steaming times of 15 and 20 hours and high-temperature treatment durations of 7 and 15 hours were chosen. Flitches 7/4 inch thick from 59 8-foot logs were divided equally into five groups. One group was the control and was not treated. The flitches in each of the other four groups were assigned to one of the treatments selected in the preliminary study. After treatment an equal number of flitches from each of the five groups were dried in the Virginia Tech solar kiln. The remaining flitches were air-dried. After drying, all flitches were ripped. to yield 2 by 4’s. Bow, crook, and twist were measured for each stud to the nearest 1/32 inch. No difference between combinations of drying method and pretreatment was found, based on the percentage of studs within each group, rejected from No. 2 structural light framing grade due to warp. Using the actual amounts of warp as a basis showed that for bow, drying method has a significant effect, and for twist both drying method and treatment were significant. Low R-squared values in the three-way analysis of variance indicated that little of the total variation could be accounted for by this model. An attempt to explain the variation by introducing logs as a. variable was unsuccessful. Most of the variation in warp was due to factors not measured. It is concluded that solar- and air-drying of S-L-R flitches without pretreatments are suitable methods of drying and should encourage S-D-R manufacturing.

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