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NWSP 10.2 Absorption Rate




NWSP 10.2


Rate of Absorption of Wiping Materials


The NWSP 10.2 Absorption Rate test method gives a technique for quantifying the rate of sorption of wiping materials. Briefly stated, a stack of wiping materials of known mass and dimensions is placed on the surface of a thermostatically controlled tank of water. The time required for the stack to wet out is recorded. From these measurements and from the mass of the wetted stack of wipers, a rate of sorption through the plane of the wiper can be calculated.

When the rate is calculated as a flux on a per-unit-area basis, it is termed the extrinsic rate of sorption, Re [mL/m2/s]. The rate calculated on a per unit – mass basis is termed the intrinsic rate of sorption, Ri [mL/g/s]. If basis weight is given in units of grams per square meter, then the two rates of sorption are related via the equation:

Re = Ri x basis weight

The test rests on three hypotheses: that the rate of sorption is independent of the area of the specimens, that the rate of sorption is independent of the number of plies used to do the test, and that the sorptive capacity of the wiper is independent of the number of plies used to do the test. These hypotheses have been shown to be valid within the limits described in this procedure.

In addition to the measurement of rate of sorption, the method also permits the simultaneous determination of basis weight and sorptive capacity.

The SI values are regarded as the official standard system of measurement for this standard test method. If other systems of measurement are used in place of SI units (including inch-pound) their values must be reported independently. Systems of measurement must not be combined in any way, but shall be regarded and reported separately


Water temperature not thermostatically controlled but maintained at room temperature (23°C). Testing consists of 3 replicates using a stack of 5, 10 and 15 wipes; each test will run for a maximum test time of 30 minutes.


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