| 摘要 |
PURPOSE:To inexpensively produce a printing plate through a simplified step, by a method wherein an erasing liquid is applied to a needless image part of a photosensitive planographic printing plate exposed imagewise to light, followed by developing and gumming, without washing the plate with water. CONSTITUTION:Either a mixed solution comprising a base-soluble acidic substance (e.g., phosphoric acid or hydrofluoric acid), a water-soluble solvent (e.g., gamma-butyrolactone) and water or an emulsified or dispersed liquid comprising a base-soluble acidic substance, a water-insoluble solvent (e.g., cyclohexane) and water, is used as an erasing liquid (having a viscoity of not higher than 200cp). Namely, a photosensitive planographic printing plate (e.g., FPD, produced by Fuji Photo Film Co., Ltd.) is exposed imagewise to light, and then the erasing liquid is applied to a needless image part detected by inspecting a printed image. Subsequently, without washing the plate with water, the plate is subjected to a developing treatment and a gumming treatment to make the printing plate (preferably, by using an automatic developing machine having both a developing part and a gumming part). |
