Abstract: A humidifying system for maintaining the moisture content of the paper at a preferred level in an electrostatic plotter. The plotter has a paper supply compartment rotatably holding a horizontal roll of plotting paper where the paper passes from the roll and through the supply compartment to a separate printing compartment. There is a powered piezoelectric humidifier for supplying cool water vapor at an outlet opening thereof. An adjustable humidistat is disposed in the paper supply compartment and operatively connected to turn the humidifier on and off as a function of the humidity in the paper supply compartment. A plastic pipe manifold is horizontally disposed across the inside of the paper supply compartment. The manifold has a closed end and an opposite end connected to the outlet opening of the humidifier. The manifold has a plurality of spaced outlet holes through sidewalls thereof along the length thereof for water vapor introduced into the manifold by the humidifier to emerge therefrom.