Variability in water vapour sorption isotherm in Japanese Larch ( Larix kaempferi Lamb.) – earlywood and latewood influences

The objective of this study was to investigate the influence of the earlywood and latewood of different annual rings of kiln dried Japanese larch wood upon the water vapour sorption properties. Samples of earlywood and latewood from different lateral positions in the tree at 1·5 m height were exposed to water vapour over a range of different relative humidities to obtain sorption isotherms. A difference was found between the behaviour of the earlywood and latewood and this became more pronounced as the distance from the pith increased. The results indicated that there was residual water trapped in the cell wall of the latewood of the more recent annual rings after the first drying curve was completed. However, when the latewood was exposed to a second sorption cycle much of the residual trapped water was no longer present. Nonetheless, there were still differences in the EMC between the earlywood and latewood.