Abstract: Filter frame (1), intended to be inserted in filter cloths of flexible materials shaped as bags, which bags during filtration are percolated by the treated fluid from the outside and inwards, the frame comprising two perforated and corrugated plates (2) placed against each other so that the ridges of one plate are in contact with the valleys of the other plate and linear contact between the plates is formed and between which lines and the surfaces of the plates channels for the filtrate are formed and an outlet (5) for collecting the filtrate, whereby the outlet opens out into one of the channels. The perforations are, in order to obtain a good flexibility and separating effect, formed as holes in a net of expanded metal.