Abstract: Stiff ink in a ink fountain of a high-speed printing press or the like is maintained at the viscosity necessary to wet a printing roller by vibrating a rod placed in the ink in the fountain. The rod is mounted on arms pinned to trunnions, one of which trunnions is fixed to an air turbine oscillator. The oscillator when activated, transmits vibrations to a trunnion to which it is fixed. The vibrations pass on to the associated arm and on to the rod to agitate the ink. The trunnions are mounted on vibration isolators on the cheeks of the ink fountain. The rod being mounted via the arms on the trunnions, is swingable in and out of the fountain for cleaning purposes as on ink changes.