Abstract: A mixer includes a vessel for storing materials to be mixed. The vessel has cylindrical inner walls. A beater assembly is rotatably mounted and centrally disposed within the vessel. The beater assembly includes a drive shaft and a plurality of helically extending mixer blades operatively connected to the drive shaft for rotational movement about an axis defined by the drive shaft. The mixer blades cooperate upon a single rotation of the beater assembly to move materials residing immediately adjacent to the inner walls of the vessel inwardly towards the axis of rotation, and to move materials residing near the axis of rotation outwardly towards the inner walls of the vessel. A motor is operatively connected to the drive shaft for rotating the beater assembly relative to the vessel.