Dampening device for offset printing machine

A dampening device for an offset lithographic printing machine of the type having a fluid fountain for containing a bath of dampening fluid, a pickup roll in said fountain adapted to extend into said bath, a plate cylinder carrying a printing plate, a rotatable fluid distribution means spaced from said pickup roll by a gap and disposed between said pickup roll and said printing cylinder and rotation means for rotating said pickup roll and said distribution means;

• the improvement comprising in that said pickup roll has a fluid retaining means thereon in the form of a fine wire mesh smooth cylindrical screen on the surface thereof with the wires of the screen comprising thread-like portions forming circumferentially evenly spaced openings where said openings are spaced uniformly radially outwardly from the peripheral surface of the pickup roll for picking up and retaining a thin film of fluid when said pickup roll is rotated in said bath, and in having gaseous blow means the center line of which is directed inwardly toward the peripheral surface of the pickup roll near said gap for breaking up said thin film into droplets and blowing said droplets onto the peripheral surface of the pickup roll where said droplets are atomized into smaller droplets and where said smaller droplets rebound from said surface to pass through said screen to be further atomized to form a fine mist and to move across said gap to the fluid distribution means.