Vertical shrink5/15/2023 ![]() The amount a piece of wood will shrink lengthwise, called longitudinal shrinkage, is so small-typically about 0.1% to 0.2%-that it is usually inconsequential to the volumetric shrinkage. The two primary planes or surfaces of wood where shrinkage takes place are across the radial plane, and across the tangential plane, corresponding to radial shrinkage, and tangential shrinkage these two values, when combined, should roughly add up to the volumetric shrinkage. Volumetric shrinkage tells how much a wood species will shrink, but it doesn’t indicate the direction of the shrinkage. In other words, since wood in its green state is at its largest dimension, and ovendry represents its driest (and therefore smallest) volume, green to ovendry is a measurement of the maximum possible percentage of shrinkage this is referred to as the wood’s volumetric shrinkage. What this means is that wood has different properties depending on the direction or orientation of the grain-it’s not the same in all directions-and one of the areas where this property is most clearly seen is in dimensional shrinkage.Īs opposed to a simple sponge or other isotropic material, wood (anisotropic) does not shrink in a perfectly uniform manner, and understanding this will help to avoid some pitfalls in preventing many shrinkage-related defects which may not crop up until months (or even years) after the wood product is finished.Ī basic measurement of shrinkage-expressed as a percentage-is the amount that the wood shrinks when going from its green to ovendry state. ![]() ![]() In addition to being hygroscopic (gaining or losing moisture from the surrounding air), wood is also anisotropic.
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