A halftone raster image suitable for rendering a continuous-tone image includes a plurality of spiral dots. The spiral dots include image pixels arranged as a first arc or as a plurality of arcs which together represent a first spiral, and non-image pixels arranged as a second arc or as a plurality of arcs which together represent a second spiral. The spiral dots enable a controlled spreading of the ink within the dot, resulting in a higher image quality, ink saving, and faster drying.

An apparatus and methods for using coatings for metal applications are disclosed. According to one embodiment, an article comprises a cured polymeric film having a first reaction product of a cationic photoinitiator and a compound suitable for cationic polymerization. The article has a second reaction product of a free-radical photoinitiator and a compound suitable for free-radical polymerization; The article has a metal substrate, wherein the cured polymeric film coats the metal substrate.

According to aspects of the embodiments, there is provided a method of measuring the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is measured using a glass roll at a lower temperature than the fountain solution. The lower temperature causes the fountain solution to undergo a change in state and in a solid state the fountain solution crystalizes and changes roll opacity with the thickness of the film. When radiated with a light source the opacity is continuously measured through the surface of the roller. The thickness of the crystallized fountain solution can then be determined via the opacity level increase by the crystallization and the impact to the opacity on the glass roll.

According to aspects of the embodiments, there is provided a method of measuring the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is measured using a diffractive optical element (DOE) configured with grating surfaces varying in a periodic fashion to hold an amount of fountain solution. When radiated with a light source the combination of the grating surface and the fountain solution therein reduces the scattering of the surface structure (“contrast”) that gives rise to a diffraction pattern. The diffractive optical element can be placed on the printing blanket of the lithography printing system or on a separate substrate.

According to aspects of the embodiments, there is provided a method of measuring the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is measured using a diffractive optical element (DOE) configured with grating surfaces varying in a periodic fashion to hold an amount of fountain solution. When radiated with a light source the combination of the grating surface and the fountain solution therein reduces the scattering of the surface structure (“contrast”) that gives rise to a diffraction pattern. The diffractive optical element can be placed on the printing blanket of the lithography printing system or on a separate substrate.

Lithographic printing plate precursors have an aluminum-containing substrate prepared using two anodizing processes to provide an inner aluminum oxide layer of average dry thickness of 300-3,000 nm and a multiplicity of inner micropores of average inner micropore diameter of ≤100 nm. An outer aluminum oxide layer is provided with a multiplicity of outer micropores of average outer micropore diameter of 15-30 nm and a dry thickness of 30-650 nm. A hydrophilic layer is disposed on the outer aluminum oxide layer at 0.0002-0.1 g/m.sup.2 and has a (1) compound having an ethylenically unsaturated polymerizable groups; a —OM group connected directly to a phosphorus atom, wherein M represents hydrogen, sodium, potassium, or aluminum; and (2) one or more hydrophilic polymers having (a) recurring units comprising an amide group, and (b) recurring units having an —OM′ group that is directly connected to a phosphorus atom, wherein M′ represents hydrogen, sodium, potassium, or aluminum.

Lithographic printing plate precursors have an aluminum-containing substrate prepared using two anodizing processes to provide an inner aluminum oxide layer of average dry thickness of 300-3,000 nm and a multiplicity of inner micropores of average inner micropore diameter of ≤100 nm. An outer aluminum oxide layer is provided with a multiplicity of outer micropores of average outer micropore diameter of 15-30 nm and a dry thickness of 30-650 nm. A hydrophilic layer is disposed on the outer aluminum oxide layer at 0.0002-0.1 g/m.sup.2 and has a (1) compound having an ethylenically unsaturated polymerizable groups; a —OM group connected directly to a phosphorus atom, wherein M represents hydrogen, sodium, potassium, or aluminum; and (2) one or more hydrophilic polymers having (a) recurring units comprising an amide group, and (b) recurring units having an —OM′ group that is directly connected to a phosphorus atom, wherein M′ represents hydrogen, sodium, potassium, or aluminum.

A white ink composition comprises an ink vehicle comprising at least one compound chosen from acrylate monomers, methacrylate monomers, acrylate oligomers and methacrylate oligomers; at least one polyol adhesive resin that is solid at 25° C.; at least one photoinitiator; and at least one white colorant. A method of printing the ink composition is also disclosed.

A white ink composition comprises an ink vehicle comprising at least one compound chosen from acrylate monomers, methacrylate monomers, acrylate oligomers and methacrylate oligomers; at least one polyol adhesive resin that is solid at 25° C.; at least one photoinitiator; and at least one white colorant. A method of printing the ink composition is also disclosed.

An apparatus and methods for using coatings for metal applications are disclosed. According to one embodiment, an article comprises a cured polymeric film having a first reaction product of a cationic photoinitiator and a compound suitable for cationic polymerization. The article has a second reaction product of a free-radical photoinitiator and a compound suitable for free-radical polymerization. The article has a metal substrate, wherein the cured polymeric film coats the metal substrate.