The prior art discloses a wide variety of vibrating screens
, devices which use them, sieve shaker, and screens for shale shakers. In shale shakers which use a plurality of screens, problems are encountered with the leakage of fluid, e.g. mud, between screens and between screens and the edges of screen supporting members. Mud which leaks through these areas is not screened; i.e. an acceptable level of the separation of liquid (e.g. oil) from cuttings or drilling solids is not achieved.