warping

wood

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Last updated

July 23, 2026

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Warping in wood refers to its twisting or distortion out of its natural shape. This occurs because wood is hygroscopic, meaning it absorbs and releases moisture from the air. When wood loses moisture, it shrinks, and when it gains moisture, it swells. These dimensional changes are anisotropic, meaning they differ in axial, radial, and tangential directions.123

The differential shrinkage and swelling, particularly between the radial and tangential directions, is a primary cause of warping. Other factors influencing warping include density, extractives, mechanical stresses, and structural abnormalities within the wood. Warping can lead to issues like opening joints, changes in cross-sectional shape, and checking (cracking). Methods to improve dimensional stability include creating products like plywood or applying water-repellent coatings.34

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wood
Shrinkage and swelling
…joints, change of cross-sectional shape, warping, checking (formation of cracks), case-hardening (release of stresses in resawing or other machining, with consequent warping), honeycombing (internal checking), and collapse (distortion of cells, causing a corrugated appearance of the surface of lumber). Thus, the fact that wood shrinks and swells constitutes a great…
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…joints, change of cross-sectional shape, warping, checking (formation of cracks), case-hardening (release of stresses in resawing or other machining, with consequent warping), honeycombing (internal checking), and collapse (distortion of cells, causing a corrugated appearance of the surface of lumber). Thus, the fact that wood shrinks and swells constitutes a great…
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