The freeness of pulp is designed to give a measure of the rate at which a dilute suspension of pulp may be drained. The freeness, or drainage rate, has been shown to be related to the surface conditions and swelling of the fibers. It is also widely used to follow the changes in drainage rate of various chemical pulps during beating and refining.  Freeness values do not necessarily correlate with the drainage behavior of pulp material on a commercial paper machine.

 

To perform adequate testing on a dry sample 30 oven dry grams are desired and the equivalent of 10 oven dry grams are desired from slush samples. This ensures proper disintegration and that a duplicate can be run on each sample to be tested. If sample availability is limited, testing can be performed using less sample or as a single determinant. The freeness test requires the equivalent of three oven dry grams for each replicate.