| abstract |
An aqueous alkaline developer for use with an imaged lithographic printing precursor comprises an aqueous alkaline medium, sodium metasilicate, a steric or electrosteric stabilizer, and a rinse aid or a phase stabilizer. It is suited for developing a lithographic printing precursor comprising, on a substrate, a coated and dried layer of a radiation-sensitive composition comprising one or more acetal resins. The developer may further contain a moderator, a dispersing agent capable of solvating a hydrophobic image colorant, and a wetting agent. The acetal resin of the precursor may be derived from polyvinyl alcohol by condensation with aldehydes. The imageable element is imageable by radiation, preferably infrared radiation, and provides good sensitivity for use in lithographic applications, such as conventional imaging systems, computer-to-plate systems or other direct imaging elements and applications when treated with the developer. The invention also provides a positive-working lithographic printing master comprising a precursor as aforesaid, imaged and developed with the developer. The invention further provides a method for cleaning the processor equipment in which the imaged lithographic printing precursor has been developed, comprising treating the deposit with an acid to yield liberated image colorant and treating the liberated image colorant with a cleaning composition. |