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Cobb Moisture Absorption Tester

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Cobb Moisture Absorption Tester
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Cobb Moisture Absorption Tester

The Cobb Moisture Absorption tester measures water adsorption quality of paper. It determines the quantity of water absorbed by nonbibulous paper, paperboard and corrugated fibreboard. It is not suitable for tests on unsized porous papers such as newsprint or blotting paper.

Water absorptiveness referes to the the mass of water absorbed in a specific time by 1 square meter of sized paper, board, or corrugated fibreboard under specific conditions.

Size or sizing are the characteristics of paper, paperboard or fibreboard that describes additive substances applied during process that improves qualities and resistance to liquids.

Cobb Moisture Absorption tester Parts:

Test Ring

It is designed to allow one side of the test specimen to be uniformly wetted the moment the soaking begins. It also allows the rapid removal of the water from the surface of the test specimen once the test period has been completed.

The Test Ring is made up of a metal ring with a 11.28 ± 0.02cm inside diameter (Area of 100cm²) a wall height of between 25 mm and 50 mm and a wall thickness of approx. 6mm. The Test Ring is mounted within a frame where it can easily be clamped upon a rubber bed surface of the base plate. All metal parts are constructed of stainless steel.

Tester Roller

The Cobb Moisture Absorption Test Roller has been designed to accompany the Test Ring and is also constructed out of stainless steel. With a smooth rolling face, it weighs 10.0 ± 0.5kg

Cobb Moisture Absorption Tester ring and roller

Cobb Moisture Test procedure

Cobb Moisture test is a method of determining the water absorptiveness of sized paper and board, including corrugated fibreboard, under standard conditions. It may not be suitable for paper of grammage less than 50 g/m2 or embossed paper. It is not suitable for porous papers such as newsprint or unsized papers such as blotting paper 

The test includes placing a dry test piece of paper under the cylinder. Secondly, pour 100ml of water for a specified period of time. Then, place the test piece on standardized blotting paper. Finally, place another blotting paper on the test piece. And use the roller to remove excess water.

The test sample is weighed before and after this procedure. As a result, it gives us the absorption rate. This is usually in grams per m2 as per the standard method.


  • It is designed primarily for non-bibulous materials and it is not suitable for unsized porous papers such as newsprint and blotting papers.
  • It is not recommended as a sizing test for writing papers or for measuring the resistance of the surface of a sheet to minute quantities of water such as in writing with a pen.


  • Compression Springs
  • Stainless Steel Ring and Base
  • Single Handed Operation
  • Fast Locking of the Sample
  • Couch Roll is included


  • Easy to use
  • Fast results


  • AS1301.411 - Methods of test for pulp and paper, Method 411: Water absorptiveness of paper and paperboard (Cobb test)
  • TAPPI T 441 - Water absorptiveness of sized (non-bibulous) paper, paperboard, and corrugated fiberboard (Cobb test), TAPPI/ANSI T 441 om-20
  • ISO 535 - Paper and board — Determination of water absorptiveness — Cobb method

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