Reversibility of Dimensional Changes in Birch (Betula Pubescens) and Scots Pine (Pinus Sylvestris L.) Wood

Abstract

The reversibility of wood shrinkage through swelling of birch (Betula pubescens) and Scots pine (Pinus sylvestris L.) as a measure of their response to changing conditions of adsorption and desorption during service was determined. Virtually all dimensional changes that occurred in the form of shrinkage during drying at both conventional and high temperatures were recovered during swelling in both species. It is suggested that minor changes in the equilibrium moisture content, which commonly occur during the life span of wood, will not result in significant dimensional changes in either species except in the tangential direction of Scots pine. Significant differences between shrinkage and swelling in the tangential direction in Scots pine where swelling was greater than shrinkage implies a higher stability of Scots pine during shrinkage compared to swelling. Hence it is expected that in the tangential direction, this species will be more stable during desorption than adsorption.