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Water absorption of corrugating medium:
water drop penetration test

Scope and Summary

In TAPPI T 831, the water absorptivity of corrugating medium is measured by dropping a drop of water on the surface of a specimen and determining the time in seconds for the drop to penetrate through the sheet and wet the lower surface. This method is applicable to corrugating medium as it is commercially produced by all processes. It is generally applicable to relatively unsized (water leaf) containerboards but may not be applicable to more highly sized boards or to grades produced in different grammage (basis weight) than those normally used in corrugating medium. Alternative methods which can be performed in the same general time period with equal repeatability do not give the same numerical results, but, in general, will rank the materials in the same order as this method.


In the past, medium was produced with semichemical pulp, and water drop could be found to correlate with the medium to liner bondability on a corrugator. Today’s mediums are made primarily from recycled and kraft fiber. Water drop can vary widely when using these fiber types with no detrimental effects on bondability.


A minimum of 10 test specimens are needed for each code to be tested. Test time is 5 minutes maximum unless noted in the test request.

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IPS cannot sell or otherwise provide standards, specifications, or test procedures to third parties.