This investigation shows how different parameters affect liquid water absorption in Norway spruce, which in its turn affects product life length and need of maintenance.

Logs from 20 trees, half of them suppressed and half of them dominant, were taken from two sites. One site had a good supply of free water (wet) and the other site was without free ground water (dry). The logs were of approximately the same breast–height diameter. The logs were sawn into boards and dried to 12% moisture content (MC). In order to evaluate water absorption, wood density and moisture content were measured by computed tomography (CT) scanning and image processing. The measurements were performed in room climate by CT scanning after 1, 3, 7 and 14–15 days of liquid water absorption in end grain and during desorption for 6 days.

The most important findings in this investigation were: - Large differences in water absorption were observed between heartwood and sapwood. The absorbed capillary water height (CWH) is higher in sapwood than in heartwood. The average CWH is about 4 times higher in the sapwood than in the heartwood after 24 hours of water absorption (MC ≥ 40%). After 14 days of water absorption the average CWH for sapwood was on the order of 3 times higher than for heartwood. There was a significant difference in heartwood/sapwood ratio between specimens from the “wet dominant” group and the other groups. Specimens from the “wet dominant” group showed the smallest difference in CWH between heartwood and sapwood. - Specimens from the “wet dominant” and the “wet suppressed” group showed the lowest CWH in sapwood. There was a significant difference in CWH in sapwood between specimens from the “wet dominant” group and the “dry suppressed” group and the “dry dominant” group for 7 and 14-15 days absorption. - Specimens from the “wet suppressed” group and the “dry suppressed” group had the lowest CWH in heartwood. There was a significant difference in CWH in heartwood between trees from the “wet suppressed” group and the other groups for 7 and 14–15 days’ absorption - There was no significant difference found in CWH between wood specimens standing with butt end or top end in water. - Trees grown with poor access to water had a larger share of heartwood and grew more slowly than trees that grew with a good supply of water.