Many wood species are highly resistant to conventional pressure treatment. To improve the chemical impregnation into Douglas-fir (Pseudotsuga menziesii Franco) lumber, the passive impregnation method had been developed. In this study, ability of the passive impregnation for lumber was compared with a conventional full cell method. Square Douglas-fir lumber with the incising density of 10,000 holes/m2 done by CO2 laser was treated by both passive impregnation and full cell method for the same treating time. Different incising densities were also used in passive impregnation to find out the optimum incising density. It was observed that there was no significant difference between these two methods for absorption of liquid, moisture content after dipping and the penetrated area both at cross and longitudinal section though the value was higher in case of full cell method. In case of different incising densities, absorption and penetration of liquid was similar for 10,000 holes/m2 and 7,500 holes/m2 but it was quite low for 5,000 holes/m2. Therefore, it can be concluded that incising density of 7,500 holes/m2 is optimum for passive impregnation. The absorption of liquid and its distribution in wood indicates that this non-pressure passive impregnation method can be a good preservative method for impermeable lumber and can be an alternative to full cell method.

Download document (233 kb)
free for the members of IRG. Available if purchased.

Purchase this document