This International Standard specifies a method for determination of the drainability of a pulp suspension in water in terms of the “Canadian Standard” freeness (CSF) number.
The “Canadian Standard” freeness test is designed to provide a measure of the rate at which a dilute suspension of pulp may be dewatered. It has been shown that the drainability is related to the surface conditions and swelling of the fibres, and constitutes a useful index of the amount of mechanical treatment to which the pulp has been subjected.
Results of this test do not necessarily correlate with the drainage behaviour of a pulp material on a commercial paper machine.
A method for the determination of drainability in terms of the Schopper-Riegler number is specified in ISO 5267‑1.