krimpuitzetting

Krimpuitzetting is a Dutch term used in materials science and construction to describe dimensional changes in materials caused by moisture and temperature fluctuations. The word combines krimp (shrink) and uitzetting (expansion or swelling). In practice, it may refer to the combined or sequential phenomena whereby a material first contracts as it dries and later expands when moisture content rises, or cycles between these states, leading to long‑term dimensional instability.

The concept is commonly applied to moisture-sensitive materials such as wood and wood-based products, polymers, and certain composites. In timber, drying lowers moisture content and causes shrinkage, while subsequent moisture uptake can lead to swelling. In polymers and composites, hygroscopic or moisture-driven dimensional changes can produce similar shrink‑ and swell‑type cycles, depending on the material and environment.

Measurement of krimpuitzetting typically involves tracking changes in length, width, or thickness relative to changes in moisture content or ambient humidity. Practically, it is expressed as a percentage change in dimension per unit change in moisture content. Repeated shrink–swell cycles can result in warping, cracking, delamination, or loss of fit in assemblies and structures.

Mitigation strategies focus on moisture control and design accommodations. This includes selecting materials with low moisture sensitivity, applying protective coatings or sealants, incorporating expansion joints, and designing tolerances that account for expected dimensional changes. See also shrinkage, swelling, and hygroscopicity.