Abstract: To ensure that a web (11) of filter material is properly passed between filter plates (25) of a filter stack (23), without skewing, which might cause leakage along the edges of the filter plates, the web is guided to the filter plates by guide rollers and, after being received from the stack of plates, passed over an inclined deflection edge (13) on a deflection element or rod, located at an angle of 45.degree. with respect to the edge of the essentially rectangular plates, so that the run-on and run-off surfaces of the web will form a web deflection angle (.alpha.) of about 90.degree., and a web plane diversion angle (.beta.) of 0.degree.. A plurality of deflection rod groups may be used, guiding webs alternately, for example, for example, to the right or left after having passed through a stack, or permitting passage of the webs through an additional stack (FIG. 13) since, upon passage about the deflection rods, the orientation of the surfaces of the filter web is reversed.