Heart dryness of Douglas fir and ability to rotary cutting: Research of alternative boiling processes. I. Moisture content distribution inside green wood and water impregnation with an autoclave.

The analysis of the moisture content variations along Douglas fir increment cores, fresh cut logs and peeled veneers allowed to confirm the low level of moisture content inside Douglas fir heartwood. Whatever the tree and the inside ring location may be, the heartwood moisture content is about 30% v s. 80 to 150% for sapwood. Several hygrothermic treatments (conventional bo iling, hot/cold baths, vacuum/pressure cycles) have been applied to II cm l ong bolts in view to measure the moisture content increasing. Only the trea tments involving vacuum and pressure appeared efficient. The heartwood mois ture content after such treatments ranged from 50% to 150%. The higher M.C, were obtained inside earlywood.