On the tropical woods, the comparative weettability measured by three methods, and also the effect of specific gravity, pH or extract with ether on the wettability, were determind.
The wettability for each wood was determined by the methods of capillary rise, inclined plate and droplet(water and urea resin). The results of the experiment are shown in Table 1. The coefficient of correlations was calculated from the results.
Then the regression line was yielded by regression analysis only when a signifficant correlation at five percent or better was recoginzed. If the correlation was not siginficant, it was either not shown or horizontal line was drawn through the mean value.
The following conclusions may be drawn from the results of the analysis.
1) The wettability behavior revealed a sharp break in the trend of the dependent variable at about 0.8 specific gravity. On the woods below 0.8 specific gravity, the correlation of the wettability determined by the three methods was significant.(Fig. 1)
2) The specific gravity had more effect on the wettability of woods below 0.8 specific gravity, followed by the extract with ether and pH. These factors had no effect on the wettability of woods above 0.8 specific gravity. (Fig. 2, 3)
3) The capillary rise method gave reproducible values of wettability but was a timeconsuming method. On the other hand, the contact angle method(inclined plate and droplet) was a quick and simple method to use. However, the values obtained by inclined plate and droplet methods showed a variation according to the researcher and to surface condition of the wood, respectively.