A dampening unit that sprays viscous application liquid to a treatment surface includes a rotating brush driven to rotate around the axis, a liquid applicator that supplies the liquid to the brush, and a brush chamber to accommodate the brush. The brush chamber includes a wall that surrounds the brush. The wall defines an ejection window for discharging viscous application liquid that is either sprayed or spun away from the brush.

A dampening unit that sprays viscous application liquid to a treatment surface includes a rotating brush driven to rotate around the axis, a liquid applicator that supplies the liquid to the brush, and a brush chamber to accommodate the brush. The brush chamber includes a wall that surrounds the brush. The wall defines an ejection window for discharging viscous application liquid that is either sprayed or spun away from the brush.