Use of Relative Density-based Schedules in Kiln-Drying Big-Leafed Mahogany (Swietenia macrophylla King) Lumber
Aileen A. Jara1*, Emmanuel D. Bello1, Stella Villa A. Castillo1,
Virgilio A. Fernandez1, and Ponciano S. Madamba2
1Department of Forest Products and Paper Science,
College of Forestry and Natural Resources
University of the Philippines Los Baños, College, Laguna
2Agricultural Bio-Process Division, Institute of Agricultural Engineering
College of Engineering and Agro-Industrial Technology,
University of the Philippines Los Baños, College, Laguna
Kiln-drying experiments were conducted to determine the seasoning characteristics of and drying schedules for small-diameter plantation-grown big-leafed mahogany (Swietenia macrophylla King) based on its relative density. Three schedules of increasing degree of severity – recommended (T7-D3), severe (T8-D4), and accelerated (modified T9-D5) were used. The study showed evidence that small-diameter plantation-grown mahogany is easy to dry as illustrated by its fast drying rate and resulting minimum defects. The mahogany boards could be subjected to temperatures as high as 82.2° C without severe drying defects. The species is further characterized by low radial and tangential shrinkage. The severe (T8-D4) and accelerated (modified T9-D5) drying schedules appeared promising for 23-year old mahogany, resulting in shorter drying times and boards comparable in quality to those kiln-dried using the recommended schedule. However, casehardening and moisture content variation were observed in all the drying runs.
The Philippine wood industry is slowly shifting to non-traditional raw materials due to the shortage of timber supply from traditional sources. This shift involves the establishment of tree plantations using fast-growing species. Because of high productivity, shorter rotation cycle, and multifarious end-uses, plantation species are considered a potential solution to the country’s timber shortage. However, research gaps need to be addressed to maximize these species’ utilization potential. Most of them present special problems as they do not have a history of utilization or may have properties different from traditional species. Most plantation species that have so far been studied were found to have setbacks in wood quality including low durability, low density or strength, and prone to warping and other drying-related defects largely due to the high proportion of juvenile wood (Alonzo et al. 1998). These wood characteristics create challenges in processing technologies such as sawing, seasoning, and machining (Bendtsen 1978).
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