Abstract: A rotary device for mixing viscous liquids within a container. A vertical rotary driven shaft is connected to a circular disc at its terminal end. Radial or tangential mixing vanes are connected to the top surface of the disc and a baffle plate or cover disc is located over the vanes to prevent vertical flow in the area of the vanes. A central flow passage is provided about the shaft. Fluid is driven laterally outwardly by the vanes and replacement fluid is pulled downwardly by a pumping action along the shaft and likewise driven laterally outwardly for mixing. A removable washer shaped flow restrictor is placed in the central flow passage, vertically supported by the inner ends of the vanes and held in place by the downward flow during rotation of the mixing device.