Improving the capability of the Schopper-Riegler freeness measurement

The aim of this study was to prepare the investigation of the influence of enzymatic treatment; the results of hydrolysis by cellulases are not shown here. The freeness (characterised by Schopper-Riegler number) of reference pulps showed great fluctuation in the parallel experiments, as this was quantified by variance components analysis. All of individual steps of the procedure were carefully examined and the method was standardised based on analysis using an Ishikawa diagram. The reproducibility and repeatability improved significantly. The required number of future replicated and repeated experiments in enzymatic treatments were calculated derived from estimated variance components of the improved process on untreated pulps.