Type and extent of biodeterioration occurring on eastern spruce trees, Picea spp., infested by spruce budworm Choristoneura fumiferana (Clem.), and its effect on the value of timber as raw material for lumber and compoition board production was investigated in New Brunswick and Nova Scotia. Moderately defoliated, severely defoliated and dead (standing) trees were examined and compared with normal trees. The results indicated that the loss in wood quality due to fungal decay and insect damage on defoliated trees was not substantial and could be ignored in the use of the wood as raw material for the products mentioned above. Dead trees were found to be deteriorated to a considerable extent, mainly as a result of fungal decay, especially on the butt ends, and contained moisture in most parts to a level considered favorable for fungal decay. Decay and insect damage present on dead trees did not affect the lumber processing rate. Lower lumber recovery, however, and especially downgrading, resulted in a 21% loss of the value of lumber recovered. Particle boards and waferboards produced from the roundwood from dead trees (6-foot bolts, 7 to 13 feet from the ground) were excellent in quality and equal to those produced from unattacked or defoliated trees. A storage study was initiated near Fredericton, N.B. Six-foot long bolts from dead, defoliated and normal trees, with and without bark, will be monitored and examined for the rate and causes of deterioration during storage.
Aligned waferboard panels were prepared, the mean and the standard deviation of measured angles of aligned face wafers were carefully determined. The importance of orientation angle and angle distribution was demonstrated for board properties such as modulus of rupture and module of elasticity. Linear and non-linear regression models were studied and a number of prediction equations in terms of strength properties were tested and reported.
The relationship of press closing time, strength properties and density profile of thick waferboard panels to mat moisture content was demonstrated in this study. Lower mat moisture contents were found to increase press clothing time but permit faster binder curing. When the distribution of mat moisture was higher in the face layers, shorter press times were achievable and a significant densification of the panel was observed.
The susceptibility of non-veneered composite panel products to decay is greater than solid timber when exposed to high moisture contents and severe decay hazard conditions. Preservative chemicals incorporated into these products at various stages of manufacture generally improve the decay resistance of these materials but certain strength properties, especially internal bond, are adversely affected. It appears from the literature survey that treatment of the composite panel products with ACA type preservative system could provide adequate protection with acceptable loss in the strength properties of the panels.
This second status report describes the effects of 1 year exterior weathering at the Ottawa site and three accelerated aging tests on thickness, bending properties, internal bond strength, surface hardness, and nail withdrawal resistance of small specimens of two commercial waferboards. Following 1 year exterior weathering, all but two properties of random short wafer waferboards were adversely affected to a greater extent than aligned long wafer specimens. Thickness change and internal bond strength retention were more or less equal for the two waferboards. Relative to 1 year exterior weathering, accelerated aging was more severe in all cases except modulus of rupture following the AFNOR V 313 test and modulus of elasticity following both the AFNOR V 313 test and the ASTM 6-cycle test. Of the three accelerated aging tests studied, the AFNOR V 313 test was the least severe followed by the ASTM 6-cycle test and the CSA 2-hour boil, the most severe test. A second outdoor test site was set up in Saskatoon, Saskatchewan and similar waferboards were mounted for exposure.