Straining method and screen

The invention relates to a method and a screen for straining filler and pigment slurries and coating mixtures in paper-making. The screen comprises an infeed chamber (8) incorporating a straining element (3) adapted to pass particulate matter smaller than a predetermined size. The material to be strained is fed to one side of said straining element (3) and the strained material is discharged from the opposite side. The straining is performed under a pressure head over the element and the hole size of the straining element (3) is smaller than 300 um and the flow rate properties of the material being strained are improved by virtue of a rotatable rotor (12) adapted to the ingoing side of the straining element (3).