ABSTRACT
Timber is not a homogeneous solid like a metal which contracts and expands equally in all directions. It has different internal arrangements along the grain and across it, so that it shrinks and swells unevenly as it loses or gains moisture. Green mature timber shrinks little along its length, more across the radial face and much more across the tangential face. Tangential shrinkage is usually 1.5–2 times as great as radial shrinkage. Unequal shrinkage causes stresses within the log that lead to splits along the weakest tissue, which is the rays. Sawn timber subjected to uneven drying will warp, the severity and type of distortion being dependent on the manner in which the log was cut.
