Wet expansion, also known as hydroexpansion, is determined as the percentage change in length of a test piece when soaked in water.
Differences in wet expansion across and along the length of a sheet are the result of the alignment of the paper fibres in the grain direction. The wet expansion properties of paper are critical in applications such as books and outdoor posters.
Standards and Accreditation
Smithers Pira testing is made in accordance with British Standard BS5879.