Effects of outdoor weathering and wood properties on liquid water absorption in uncoated Norway spruce cladding
2011
Vestøl, Geir I. | Sivertsen, Mari Sand
A comparison of liquid water absorption in uncoated Norway spruce (Picea abies L.) claddings before and after 1 year of outdoor weathering was performed. The study was based on 150 specimens from two sites with high-productive forest and two sites with low-productive forest in southern Norway. The specimens included inner and outer boards; density, annual ring width, and proportion of heartwood were recorded. Water absorption increased after weathering. The relative change of short-term absorption was larger for outer boards than for inner boards, whereas it did not vary between origins. The outer boards also had more cracks than the inner boards after weathering. The differences between inner and outer boards were explained by different heartwood proportion and different annual ring orientation. The variability of short-term absorption increased after weathering since the sample groups with the highest initial absorption also had the largest increase after weathering. The change of long-term absorption did not vary between inner and outer boards or between origins.
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