Extent of dimensional changes during staggered seasoning in Pakistan-grown eucalyptus wood
D. M. Zahid A C and A. Majeed BA University College of Agriculture, Bahauddin Zakariya University, Multan.
B Assistant Professor (Forestry and Range Management), University College of Agriculture, Rawla Kot, Azad Kashmir.
C Corresponding author. Email: hafi@mul.paknet.com.pk
Australian Journal of Experimental Agriculture 45(1) 121-125 https://doi.org/10.1071/EA03094
Submitted: 8 May 2003 Accepted: 12 March 2004 Published: 21 February 2005
Abstract
Eucalyptus is an exotic species that has been grown in Pakistan for over 2 decades. It is fast growing and an alternative to indigenous hardwood species, but growers are facing problems regarding maximum utilisation, predominantly due to seasoning defects. Attempts are being made to assess the extent of dimensional changes during seasoning so that appropriate procedures can be developed and applied to reduce defects occurring during this time. Specimens were taken from farm grown eucalyptus wood at the Postgraduate Agricultural Research Station. Seasoning was applied in 2 stages. Changes in wood dimension measured were shrinkage (longitudinal, radial, tangential and volumetric) and warping (bending and twisting). From this study it can be concluded that intermediate sized samples that were symmetrically sawn were more stable than smaller samples sawn unevenly. The data indicated that specimens neither too large nor too small could be favoured for seasoning. Two-step seasoning is preferred over 1-step seasoning, and sawing of wood with rectangular specimens (boards) cut with the wide face radial relative to the growth rings is ideal, even though boards with lesser width were recovered. This is because internal stresses are disposed off symmetrically and counter balance each other, which reduces defects. Seasoning efficiency of these logs was enhanced and the stresses were set due to wood plasticity. Further degradation was unlikely when wood was re-sawn after partial seasoning.
Additional keywords: lumber recovery, seasoning defects, 2-step seasoning.
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