Liquid water absorption in uncoated Norway spruce (Picea abies) claddings as affected by origin and wood properties

Uncoated Norway spruce specimens from different spatial positions within stems from two origins with different growth conditions were exposed to liquid water over a prolonged time, and apparent diffusion coefficients and rates of void filling were calculated from sorption curves. Both apparent diffusion and rate of void filling were significantly affected by origin and by the difference between inner and outer boards. The differences between inner and outer boards were explained by heartwood proportion and density, but some effects of origin remained when these properties were accounted for. The apparent diffusion coefficient was reduced by increasing density, and increased by increasing heartwood proportion. Void filling rate was reduced by both increasing density and increasing heartwood proportion. Since the effect of heartwood proportion was more pronounced in the material from the highly productive area, it may have been confounded with properties of juvenile wood.