Water absorbency measures the amount or rate of water absorbed by the surface of paper and board. Different methods can be used depending on the absorbency of the material and its intended application.
Cobb test - sized papers and paperboards
The Cobb test determines the amount of water absorbed into the surface by a sized (non-bibulous) paper, paperboard, and corrugated fibreboard paper or paperboard sample in a set period of time, usually 60 or 180 seconds (Cobb60 or Cobb180). Water absorbency is quoted in g/m2.
Water absorbency can influence properties including printability and the setting rate of water-based adhesives.
Smithers is ISO 17025 accredited for the determination of water absorption of paper and paperboard to BS EN 20535 and International standard ISO 535. Testing can also be made in accordance with Tappi T441 and ASTM D3285 and with other test liquids.
Klemm method - unsized papers and paperboards
For highly absorbent unsized papers, including blotting papers, the Klemm method measures the rise of water through a test piece over a defined period.
Smithers tests in accordance with BS 6504.
Cage method - tissue paper and tissue products
Water absorbency time and water absorption capacity of tissue paper and tissue products can be determined using the cage method in accordance with DD ENV 12625-8.
Water absorbency rate
This method measures the liquid absorption rate of highly absorbent paper, paperboard and paper products. A defined volume of liquid is applied to the surface and the time taken for it to be absorbed is measured.
It can be used to evaluate materials such as tissue, towelling and blotting papers. Other liquids, including ink, oil and milk, can also be used to compare material performance for specific applications.
Testing is available in accordance with TAPPI T432 or ASTM D5802.
Talk to our experts about your paper, board or tissue material and the absorbency properties you need to evaluate.
