A ribbon blender consists of a horizontal trough containing a central shaft and a helical ribbon agitator. Two counteracting ribbons are mounted on the same shaft, one moving the solid slowly in one direction, the other moving it quickly in other. The ribbons may be continuous or interrupted. Mixing results from the turbulence induced by the counteracting agitators, not from mere motion of solids through the trough. Some ribbon blender operates batch wise with the solids charged and mixed until satisfactory; others mix continuously, with solids fed in one end of the trough and discharged from the other. Ribbon Blenders are effective mixers for thin pastes or for powders that do not flow radially. The whole assembly is fitted on rigid MS structure. The trough is unloaded through an opening in the bottom. The setup studies in principles of mixing and can be operated as batch wise or continuously.