Abstract: An improvement for centrifugal sifter units having an elongated sifting chamber having a central axis, a coaxial screen surface therein and a series of paddles mounted on a shaft driven for rotation about the central axis for urging siftable material through the screen surface to separate fines from overs, comprises a series of nozzles mounted on the shaft for rotation therewith. The nozzles are oriented to direct gas streams at the screen surface whereby agglutinating fines are dislodged from each other and are directed through the screen surface. A source of compressed gas is operatively connected to the nozzles. The gas streams may be ionized to further improve throughput.