Abstract: A developer is disclosed for lithographic printing elements. The developer is single phase and contains an aliphatic cyclic carbonate, water, and optional ingredients.

Abstract: Emulsion developers for diazo-sensitized printing plates are disclosed which are characterized by an oil phase containing a partially water-soluble aliphatic cyclic carbonate having the formula: ##STR1## where n is an integar from 0-2, and Z is selected from hydrogen, C.sub.1 -C.sub.3 alkyl, hydroxyl alkyl or chloroalkyl, chlorine, hydroxy or phenyl. The preferred carbonate is propylene carbonate.

Abstract: A developer is provided for lithographic plates or the like having a layer including a diazonium material, which developer enhances the effectiveness of the photolysis to which the plate had been subjected, with the result that the exposure time needed for the plate is substantially reduced. The developer, which thus enhances the apparent photospeed of the plate, includes an insolubilizing reactant that reacts with diazonium groups of diazonium materials on the plate that were not removed by photolysis during exposure in order to decrease the solubility of the diazonium material.

Abstract: Plates such as those used in lithographic printing and photoresists such as those used in preparing printed circuit boards and the like are provided with a photopolymerizable photosensitive diazo resin that is unusually stable. The diazo resin is laid down from a stabilized diazonium composition that is an emulsion including the selected diazo resin, a purine derivative, especially a theophylline derivative, preferably in combination with a salt of a low molecular weight alkyl sulfonic acid or other supplementary stabilizer component.