Svellingstester

Svellingstester is a term used for instruments and setups designed to measure how much a material swells when it absorbs moisture, solvents, or is exposed to heat. The tests are used to assess dimensional stability and how materials behave in hygroscopic or solvating environments.

The basic principle involves conditioning a specimen with defined dimensions in a controlled environment where humidity, temperature, or solvent vapour can be precisely set. A displacement sensor, optical measurement, or a dedicated swelling cell records changes in length, width, thickness, or volume over time. Swelling is usually reported as a percentage change relative to the original dimension, for example one- or three-dimensional swelling.

Configurations vary by material and purpose. In polymers and composites, swelling tests often use immersion or vapour exposure with continuous length or thickness measurements. In wood, paper, and textiles, tests may be conducted in humidity chambers to observe anisotropic swelling along different directions. For soils and clays, swelling tests can involve swelling pressure measurements or oedometer-style setups that quantify the expansion and associated pressure under confinement.

Results from svellingstester inform material selection, product design, and quality control by indicating how much a material will expand under expected service conditions. They can help predict dimensional changes during processing, storage, or in use, and are often specified or referenced in standards tailored to the material class.