A filter press consisting of plates with a gridiron surface alternating with hollow frames, all of which are held by means of lugs, on the press framework. The corners of both frames and plates are cored to make continuous passages for pulp and solution; the filter cloth is placed over the plates. The pulp passageway connects with the large, square opening in the frame; the solution and passageways connect with the gridiron surface of the plate. The Dehne and the Merrill are well-known types.