The moisture content of paper and paperboard is the quantity of water present and measurable in paper. This will vary according to the environment and the moisture added during manufacturing and conversion processes. Uniform moisture content is critical for paper to be free from distortions such as curl, twist and waviness which cause printers and copiers to jam.
The moisture content of paper can vary at any given relative humidity depending on whether the moisture was desorbed (brought into equilibrium from a higher relative humidity) or adsorbed (brought into equilibrium from a lower relative humidity) - the hysteresis effect.
Smithers Pira determines the moisture content of paper and paperboard by the oven-drying technique. The paper is weighed before and after oven drying at 105°C. Results are quoted as a percentage (%) moisture content of the original or dry sample weight.
Standards and Accreditation
Smithers Pira testing is UKAS, ISO 17025 accredited to British standard BS EN 20287 and International standard ISO 287. Smithers Pira can also test in accordance with Tappi T412.