Provided are an on-press development type lithographic printing plate precursor having a support and an image-recording layer on the support in which the image-recording layer contains a coloring compound capable of having a coloring reaction with a decomposition product generated by exposure of the image-recording layer, and an on-press development type lithographic printing plate precursor having a support and an image-recording layer on the support in which the image-recording layer contains a compound represented by Formula 1C or Formula 2C and an electron-donating polymerization initiator. In Formula 1C and Formula 2C, R.sup.1C to R.sup.4C each independently represent a monovalent organic group, L.sup.1C and L.sup.2C each independently represent a divalent organic group, A.sup.C represents OH or NR.sup.5CR.sup.6C, and R.sup.5C and R.sup.6C each independently represent a monovalent organic group.

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The present disclosure provides an on-press development type lithographic printing plate precursor having a support, an image-recording layer, and an outermost layer in this order, in which a contact angle of a water droplet on a surface of the outermost layer that is measured 2 seconds after the water droplet is landed by an airborne water droplet method is greater than 36°. The present disclosure also provides applications of the on-press development type lithographic printing plate precursor.

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 by using phase shifted monochromic light to produce optical path differences through the fountain solution film. The intensity of the reflected light through the fountain solution film is very sensitive due to the phase shifted light so interference fringes are easier to delineate and fountain solution thickness measurement more reliable.

An apparatus and method for measuring the thickness of fountain solution (FS) in a Digital Architecture for Lithographic Ink (DALI) printing system by transferring the FS to an optical roller with the properties of a lens and measuring the resulting effect on the refraction of an image captured through the lens. The optical roller may comprise a clear or glass cylinder forming a Fresnel lens cylinder having an engineered surface of known surface roughness and wherein the roller is placed adjacent the image member blanket. A heat source is used to evaporate the FS from the blanket for transfer to the optical roller where the FS wets the roller surface to different degrees based on the FS thickness relative to Fresnel ridge depth. Changes to the optical refraction through the lens varies with the FS thickness. An image sensor (e.g., a CCD camera or image analysis system) evaluates the image through the optical roller for FS thickness determination.

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 by using phase shifted monochromic light to produce optical path differences through the fountain solution film. The intensity of the reflected light through the fountain solution film is very sensitive due to the phase shifted light so interference fringes are easier to delineate and fountain solution thickness measurement more reliable.

Provided are: an on-press development type planographic printing plate precursor having a support, an image-recording layer, and an overcoat layer in this order, in which a content of an inorganic compound in the overcoat layer is zero or is more than 0% by mass or less than 1% by mass with respect to a total mass of the overcoat layer, and the image-recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and an oil agent; and a method of preparing a planographic printing plate and a planographic printing method in which the on-press development type planographic printing plate precursor is used.

Provided is a method for production of an aluminium strip for lithographic printing plate supports from an aluminium alloy including (in wt %): 0.05%Si0.25%, 0.2%Fe1%, Cu max. 400 ppm, Mn0.30%, 0.10%Mg0.50%, Cr100 ppm, Zn500 ppm, Ti<0.030%, the remainder aluminium and unavoidable impurities individually at most 0.03%, in total at most 0.15%. In the method, a rolling ingot is cast from an aluminium alloy, and the rolling ingot is homogenised. Further, the rolling ingot is hot rolled to a hot strip final thickness, and the hot strip is cold rolled to final thickness of between 0.1 mm and 0.5 mm. The product of the relative final thicknesses of the aluminium strip after the first and after the second cold rolling pass of the aluminium strip is 15% to 24%.

A method of imaging printing plates uses a single imaging device having at least one laser delivering, in an imagewise manner, pulsed electromagnetic energy of pulse duration not greater than 110.sup.6 seconds. Such an imaging method permits the imaging of a plurality of types of printing plates irrespective of any sensitised imaging chemistry contained in their coatings.

The imaging sensitivity of negative-working lithographic printing plate precursors is improved by removing ozone from the ambient air surrounding the precursors that can be stored near an imaging means such as a platesetter prior to use. Ozone can be removed using a suitable filter containing activated charcoal or other ozone decomposing means, through which ambient air is filtered before and during the imaging process.

A method for setting up a lithographic printing press is provided which reduces the make-ready time of on-press developable printing plates so that less copies are wasted. The method uses an ink boost at the startup of the press by presetting the inking system to a configuration whereby the amount of ink supplied to the plate is different from the amount prescribed by standard printing conditions. The ink boost can be positive or negative and can be made dependent on the difference in the image coverage between plates used in successive print jobs or on different paper types used in successive print jobs.