Fine Material Washers use hydraulic separation with water as the medium to clean and classify sand particles by weight. Larger particles weigh more, sink and are collected in the bottom of the trough. The sand particles are transported to the inclined discharge end by a double pitched steel spiral shaft with replaceable cast wear shoes. The smaller lighter unwanted particles are floated to the surface of the claim settling pool and are discharged over the weirs. Dewatering occurs as the spiral shaft transports the settled sand up the incline of the trough and is discharged.