Kiln Drying of Acacia mangium Willd Wood: Considerations of Moisture Content before and after Drying and Presence of Wet Pockets

Abstract

Acacia mangium is an important plantation species cultivated in Costa Rica and other tropical countries worldwide. However, wood uses have been limited due to drying-related problems such as high initial moisture content (MCi) and high variability in final moisture content (MCf). The objective of this study was to investigate the causes of these problems. Climatic conditions where trees grow, tree height, grain pattern, drying schedules, distance from pith, and sapwood or heartwood presence were considered. Results showed an average MCi of 127% ranging from 58 to 186%. MCi variation was influenced by climatic conditions, tree height, and grain pattern. Average MCf was 19%, ranging from 9 to 52%. Lack of MCf uniformity after drying is influenced by tree height, drying schedule, and the interaction of both factors. Wet pockets were also found to develop during drying. Lumber from trees growing in humid tropical climates subjected to a low relative humidity drying schedule as well as rift-sawn or double rift-sawn lumber was likely to develop wet pockets.