Moisture control of softwood square lumber: A method for classifying lumber by moisture content estimated from density
1998
Nakajima, A. (Hokkaido. Forest Products Research Inst., Asahikawa (Japan))
For the purpose of obtaining uniform moisture content of todomatsu (Abies sachalinensis Masters) square lumber, a method for classifying green lumber by moisture content estimated from the density was examined. This paper also reports the effects of the final moisture content and lumber storage after kiln drying. The following results were obtained: 1) It might be possible to conclude that the moisture content generally varies too much after kiln drying because of large dispersion of the initial moisture content. The final moisture content remained higher when the initial moisture content was higher. 2) The confidence intervals of moisture contents estimated from equations in which a representative dimension and oven-dry density of the species were +- 21.6% when the reliability coefficient was 95%, and +- 12.6% with a reliability coefficient of 75%, for the values estimated from a linear regression equation. 3) For accurate estimation by this method, techniques for measuring the oven-dry density of lumber and accurate measurement of the volume of lumber before drying are required. 4) The frequency distribution of final moisture content in low-moisture-content lumber estimated from the density of green lumber was comparatively uniform. On the other hand, lumber with high initial moisture content required an extension of drying time. 5) The ratio of lumber with a moisture content of under 20%, was 62% of all lumber in the case of an average 20% moisture content. To obtain a 90% ratio of lumber with a moisture content of under 20%, the average final moisture content should be at most approximately 16%. 6) Lumber storage after drying was very effective for obtaining an uniform moisture content for all lumber
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