Wet pockets in kiln-dried Gmelina arborea lumber

In drying Gmelina arborea there are usually great differences in the final moisture content (MC_f) between and within boards. In this research, the causes for the unevenness of MC_f were studied. Wood from two young plantations (six years old) and two older plantations nearing rotation age, i.e. 10 to 12 years were sampled. The large variation in MC_f was caused mainly by wet pockets (WP). WP were located in the heartwood area and not in the sapwood. WP were present in 37.2% of the dried heartwood boards. Mean MC_f in the cross section of boards varied between 15 to 35% and humidity in the WP exceeds 60%. WP were present in the radial orthotropic direction in 31.2% of the boards and only 1.6% in the tangential orthotropic direction. Logs from the lower part of the tree were more likely to produce WP compared with logs from the upper part, which had only less than 10% of the total WP. Young trees showed less WP incidence than older trees. The results suggested that the presence of wetwood, i.e. wood infested by anaerobic type bacteria was responsible for the formation of WP.