CAN/CGSB-9.0 No./N° 2-93

1.1 The Canadian Standard Freeness test is designed to give a measure of the rate at which a dilute suspension of pulp may be dewatered. The drainage rate, or freeness, has been shown to be related to the surface conditions and swelling of the fibres, and is a useful index of the amount of mechanical treatment given to the pulp. 1.2 The procedure was originally designed to yield a test value suitable primarily for the control of manufacture of groundwood pulp. It is also widely used to follow the changes in drainage rate of various chemical pulps during beating or refining. 1.3 Treatments which produce a large proportion of fines may sometimes cause an anomalous rise of freeness (false freeness) usually at values below 100 mL. 1.4 Freeness values do not necessarily correlate with the drainage behaviour of pulp material on a commercial paper machine.