Further Observations on Longitudinal Shrinkage of Softwoods

Reported here are findings on longitudinal shrinkage in the following softwoods: ponderosa pine (P. ponderosa), white fir (Abies concolor), shortleaf pine (P. echinata), longleaf pine (P. palustris), monterey pine (P. radiata.) loblolly pine (P. taeda), and Douglas-fir (Pseudotsuga menziesii). Samples measured were blocks of 3 4-inch square cross section and 6 inches long. A section 1/8-inch thick was cut from the radial face of the three southern pines and separation made of the springwood and summerwood. Summerwood strips elongate slightly in drying from the green to the air-dry condition (the greatest elongation occurring at the base of the tree), but decrease in length with continued drying to the oven-dry condition, springwood strips normally shorten slightly in drying from the green to .the air-dry condition and shorten appreciably on drying to the ovendry condition. Softwoods, on the average, change only a few hundredths of a percent in drying to air-dry but shorten from 0.1 to 0.2 percent at the ovendry condition. Rapid growth in general is not a cause of excessive longitudinal shrinkage of softwoods.

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