Rates of Change in the Dimensions and Moisture Contents of Wooden Panels resulting from Changes in the Ambient Air Conditions

THE equilibrium moisture content of timber is dependent upon the humidity of the ambient air, and consequently a change in the humidity will bring about a change in the moisture content. An increase in the air humidity at a given temperature will lead to an increase in the moisture content of wood, which in turn will cause it to expand, whereas a decreasing humidity is accompanied by shrinkage. 'Movement' longitudinally, i.e. in the direction of the fibres, usually is very small and consequently can for most purposes be neglected. Expansion and contraction across the grain may, however, be considerable. Much information has been made available