Abstract: The presence of unwanted ink-receptive sections on developed positive-working lithographic plates due to shading by plate-holding clamps during imaging, is avoided by the use of clamps that are substantially transparent to the imaging radiation. In the case where the plate precursors can be imaged by heat, the presence of unwanted unexposed sections can also be avoided by selectively heating those sections shaded by the clamps, while avoiding heating the image section of the plate.

Abstract: The presence of unwanted ink-receptive sections on developed positive-working lithographic plates due to shading by plate-holding clamps during imaging, is avoided by the use of clamps that are substantially transparent to the imaging radiation. In the case where the plate precursors can be imaged by heat, the presence of unwanted unexposed sections can also be avoided by selectively heating those sections shaded by the clamps, while avoiding heating the image section of the plate.

Abstract: A positive-working lithographic printing plate is used to provide a positive image without a post-exposure baking step and without any floodwise exposure steps. The printing plate includes a layer that is imageable using an infrared radiation laser. This layer consists essentially of a phenolic resin, an infrared radiation absorbing compound, and a dissolution inhibitor that is non-photosensitive and is capable of providing sites for hydrogen bonding with the phenolic moieties of the binder resin. These printing plates are developed with an alkaline composition that includes an alkali metal silicate, a thickener and a fluorosurfactant or phosphate ester hydrotrope.

Abstract: An alkaline developing composition for processing a lithographic printing plate includes an alkali metal silicate, at least 6 weight % of a thickener such as glycerine, and a nonionic fluorosurfactant or a phosphate ester hydrotrope. Lithographic printing plates that can be developed using this composition are either positive- or negative-working, and include both positive- and negative-working thermal plates.

Abstract: An alkaline developing composition for processing a lithographic printing plate includes an alkali metal silicate, at least 6 weight % of a thickener such as glycerine, and a nonionic fluorosurfactant or a phosphate ester hydrotrope. Lithographic printing plates that can be developed using this composition are either positive- or negative-working, and include both positive- and negative-working thermal plates.

Abstract: Aqueous alkaline developing compositions useful in the development of negative-working lithographic printing plates are comprised of an organic solvent, an anionic surface active agent, an alkali metal tetraborate, an aliphatic monocarboxylic acid, an aliphatic dicarboxylic acid, an alkali metal citrate, a poly(alkylene glycol), an alkali metal salt of an hydroxylated aromatic carboxylic or sulfonic acid and sufficient alkaline buffering system to provide an alkaline pH. The developing composition is resistant to oxidation, highly effective in dissolution-type processing, able to effectively desensitize the background areas of the printing plate, and capable of preventing excessive deposits in a processing machine and rapidly redissolving deposits that do form.

Abstract: Aqueous alkaline developing compositions useful in the development of negative-working lithographic printing plates are comprised of an organic solvent, an anionic surface active agent, an alkali metal tetraborate, an aliphatic monocarboxylic acid, an aliphatic dicarboxylic acid, a long chain aliphatic amine and sufficient alkaline buffering system to provide an alkaline pH. The developing composition is resistant to oxidation, highly effective in dissolution-type processing, able to effectively desensitize the background areas of the printing plate, and effective in enhancing the oleophilicity of the image areas of the printing plate.