Sorting southern pine lumber to improve drying

The moisture content (MC) of green southern yellow pine lumber varies from 40 to 161 percent. Separation of green lumber by MC before drying would presumably result in more efficient drying and in less variation in final MC. To test the advantages of weight sorting, green lumber was separated into heavy, medium, and light weight classes. Pieces in each weight class were subgrouped into high and low specific gravity (SG) groups. Groups were dried separately by a standard commercial high-temperature schedule. Weight sorting resulted in segregation according to green MC, but values were confounded by SG. Within weight classes, SG had a pronounced effect on MC. In general, the lower SG pieces had higher MC. Lighter weight charges dried more rapidly than heavier weight charges. Board-to-board variation in dry MC was less for all separate weight classes than for unseparated control charges.

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