Physical effects of the pulsation preservative treatment process on northeastern red spruce (Picea rubens. Sarg.)

Partially air-dry and green wood was treated using five different pulsation schedules (i.e., each had a different number of high pressure cycles and different peak pressures (200 or 300 psi (1.38 or 2.07 MPa)). The strength and stiffness of the treated wood were evaluated according to ASTM Standard D 143. Microscopic examination documented the condition of bordered pits within the treated zone of boards having the greatest and the least treatment from each run. The modulus of rupture was significantly lowered by treatment but modulus of elasticity was not affected. Overall and within each sample group, 99 percent of the pits examined were aspirated. An evaluation and comparison of the best and most poorly treated specimens from each run found that 1 and 2 percent of the pits were aspirated in the poorly and well-treated specimens, respectively. One fourth of the specimens had a significant number aspirated in the same direction and most of these appeared to be located at the inner edge of the treated zone. This distribution may be indicative of changes in the direction of aspiration induced by the treatment process.

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