A coefficient of friction (COF) sensor on a carrier roll surface wetted with fountain solution transferred from an imaging member measures COF of the wetted carrier roll surface in real-time, even between or during printing operations. The transferred fountain solution may be concentrated and/or chilled to solidify before the measurement. The measured COF is used in a feedback loop to actively control the fountain solution layer thickness by adjusting the volumetric feed rate of fountain solution added onto the imaging member surface during an imaging or other printing operation to reach a desired uniform thickness for the printing. This fountain solution monitoring system may be fully automated.

A doctor blade holder and adjustment mechanism that may be utilized with a flexographic printing system. The doctor blade holder and adjustment mechanism may utilize a constant displacement of the doctor blade against an anilox roller, rather than a constant force, to reduce ink build up on the back side of the doctor blade, and subsequently, intermittent dropping of the accumulated ink onto the post-shearing side of the anilox roller (“spitting”). The doctor blade holder and adjustment mechanism may provide adjustability of a combination of doctor blade pressure, angle and displacement.

A printing press for printing on metal cans includes a plurality of inkers. Each inker prints a different color ink on the cans, and includes a first module, a second module, a roller and a support member. The first module has motors to drive output shafts. The second module has ink displacement units, an ink inlet to provide ink to the ink displacement units, ink channels to transfer ink from the ink displacement units to ink outlets of the second module and input shafts to removably couple to the output shafts of the first module. The roller receives ink from the ink displacement units and transfers the ink toward the cans. The support member supports the first and second modules in at least one position relative to the roller. The support member facilitates removal of the second module by a press operator for cleaning the ink channels.

A flexographic printer is provided with: a printing plate for transferring ink at an ink transfer site to an object to be printed S; an anilox roll for supplying ink to the printing plate at an ink supply site; a plate cylinder on which the printing plate is wound and rotated; and an ink solvent supply unit for supplying a solvent for the ink on the surface of the printing plate in a post-ink transfer region that is downstream of the ink transfer site in the plate cylinder rotation direction and upstream of the ink supply site in the plate cylinder rotation direction.

In example implementations, a storage apparatus is provided. The storage apparatus includes a sealed reservoir partially filled with a print agent. A float is partially submerged in the print agent. A weight is coupled to a submerged portion of the float. A vent is coupled to the float and an opening in the sealed reservoir. A valve is coupled to an unsubmerged portion of the float.

In example implementations, a storage apparatus is provided. The storage apparatus includes a sealed reservoir partially filled with a print agent. A float is partially submerged in the print agent. A weight is coupled to a submerged portion of the float. A vent is coupled to the float and an opening in the sealed reservoir. A valve is coupled to an unsubmerged portion of the float.

A device for setting at least one operating parameter of ink for a printing process of a rotary printing press having an inking system which has a doctor blade device with a doctor blade chamber containing the ink for the printing process, and an ink reservoir from which ink can be supplied to the doctor blade chamber, includes a supply system which allows ink to be supplied inside the inking system. The supply system can be switched to a setting mode (I) or to a production mode (II), the operating parameter being automatically set in the setting mode (I) and no ink being supplied to the doctor blade chamber, and the supply system supplying ink to the doctor blade chamber in the production mode (II).

A print material container comprising a body, a transfer mechanism, an inner connector, and an outer connecter. The transfer mechanism is to move print material in or out of the body. The inner connecter is on a connecting side of the body, and is to couple to a first location of an image forming apparatus to provide print material to the image forming apparatus. The outer connecter is on the connecting side of the body, and is to couple to a second location of the image forming apparatus to collect or receive unutilized print material transferred or received from the image forming apparatus.

A method for ink-based digital printing includes applying a uniform layer of dampening fluid to a surface of an imaging member; laser patterning the dampening fluid layer by selectively removing portions of the dampening fluid according to digital image data; and inking the laser-patterned dampening fluid layer on the imaging member surface with a aqueous heterogeneous ink to form an ink image, wherein the aqueous heterogeneous ink self-coalesces before the ink is transferred from the imaging member surface.

A method for ink-based digital printing includes applying a uniform layer of dampening fluid to a surface of an imaging member; laser patterning the dampening fluid layer by selectively removing portions of the dampening fluid according to digital image data; and inking the laser-patterned dampening fluid layer on the imaging member surface with a aqueous heterogeneous ink to form an ink image, wherein the aqueous heterogeneous ink self-coalesces before the ink is transferred from the imaging member surface.