Abstract: Paper or paper board is made by adding cationic polymeric retention aid to a cellulosic supension, shearing the suspension to degrade the resultant flocs, aggregating the suspension by adding an aqueous composition of bentonite or other anionic bridging coagulant in the presence of anionic dye, pigment or optical brightening agent, and forming paper from the aggregated suspension.

Abstract: A suspension is dosed with a coagulant and then with a flocculant and is dewatered to form a thickened sludge or cake and separated liquor, and control of the dewatering performance is improved by adding the flocculant at a predetermined dosage, monitoring the charge in the separated liquor (or monitoring other dewatering parameter of the separated liquor or suspension) and adding coagulant at a dosage selected in response to the monitored charge or other parameter value in order to maintain the value substantially at a preselected optimum value.