New Dry Kiln Practices

The average dryness of the western pines as shipped is thoroughly established by an extensive survey conducted by Western Pine Association in 1949 and 1950 in which 5,620 moisture content readings were taken on stock ready for shipment at 70 mills scattered through five producing states. These tests showed an average of 10.1 percent for 1 inch common grades. This is a lower moisture content than most uses of our common grades require, but it is evidence that the manufacturers of western pines are meeting their responsibilities in turning out well-dried lumber of all grades. The question is raised whether a good job of drying in a western mill assures the consumer of getting lumber in the same condition in which it left the kilns. At many plants the kiln superintendent has no authority beyond the unstacker, but unfortunately his responsibility often does not end until the lumber is used. If anything goes wrong in the interim the blame promptly rests on the dry kilns or the dry kiln operator. Well-dried lumber stacked for 3 weeks in covered sheds may attain moisture contents as high as 19 percent near the ends of boards and on the surfaces of boards on the edge of bulk-piled stacks. If the stock were run S4S before being put in the shed, the ends would be over-width. If sold locally and laid edge to edge, the carpenter would either have open edge-joints at the center of the boards, or if he drove them up tight, the boards would be sprung. Later, when moisture content evened up, edge joints would open up near the ends. Properly dried lumber is often mishandled in transit by the sawmill and retail yard. Everyone having anything to do with the handling, machining, storage, sale, or transportation of dry lumber has responsibility in the matter of getting dry lumber properly used.

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