Anisotropic Shrinkage and Swelling of Wood

The shrinkage of wood is different in the three principal directions longitudinal, radial and tangential (Table 4.1). Typical oven-dry shrinkage values for medium density woods would be  

To a first approximation the longitudinal shrinkage can be ignored. The volumetric shrinkage then becomes  

Lumber is not used in the oven-dry state. For many uses the desired in-service moisture eontent falls within the range of 8-15% moisture content. The shrinkage will then be only a half to three-quarters of the oven-dry shrinkage value. Therefore the timber trade is more interested in shrinkage values from the green to 12% moisture content (Table 4.1). These values indicate to the sawmiller the green 

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