Abstract: The invention relates to a method and apparatus for manufacturing paper or like products which contains retention agent and inorganic filler. The retention and technical properties of the paper are enhanced by coflocculating the filler with a cellulosic material having a large specific surface area (fine pulp) prior to introducing floc suspension into the stock, and by subjecting the flocs to a floc size-controlling shearing process in a particular reaction vessel to produce flocs that have a mean particle size within the range of 2-4 mm. The particular reaction vessel used herefor incorporates a mixing zone, a flocculation zone, separator means located between the mixing zone and flocculation zone, a shearing zone and a sedimentation zone.