By controlling the process stock's dwell time in the vessel, it is fundamentally possible to reduce every process stock to any desired grain size in a single operation. Demands on fineness are particularly high in the production of varnish paints, printing inks and audio tape compounds. Some mill vessels come with jacket cooling, and in some there is also additional cooling of the agitator. Depending on the load the agitation shaft is sealed by stuffing box packings, shaft lip seals or mechanical seals, primarily double mechanical seals. The most distinctive design feature of mechanical seals for agitator mills is the rotating counter ring on the product side, by means of which the process stock and grinding medium are spun off. A PTFE wiper is positioned over the stationary seal face dynamically supported by an O-ring and protects the latter from the abrasive product. Buffer fluid applied to the inside of the sealing gap enhances the lubrication and cooling of the sliding faces through its centrifugal force. Furthermore, the integrated pumping screw provides forced circulation and the guide sleeve for favourable routing of the buffer fluid, resulting in optimal heat transfer. In agitator mill seals ceramic acting against tungsten carbide with nickel bonding are used on the product side as face materials.