| 摘要 |
Exposed presensitized plates are treated with an alkaline developer and a replenisher therefor utilizing a conveying type automatic developing maching having a part for dipping and developing the presensitized plate, the machine being provided with a plate for preventing contact between the developper and air. The method is characterized in that the developer and the replenisher therefor are aqueous solutions of an alkali metal silicate and that the ratio, [ SiO2 ] / [M2O] (wherein [SiO2] is the molar concentration of SiO2 and [M2O] is that of an alkali metal oxide M2O), of the replenisher ranges from 0.6 to 1.5. Although a developer mainly composed of a silicate is used in the method, the method makes it possible to stably and rapidly continue the development processing for a long time period, the contamination of an automatic developing machine is very low and washing operations can be easily performed. Moreover, there are not observed deposition of feculences thereon during the processing. In addition, the method also makes it possible to reduce the amount of the replenisher to be used. Thus lithographic printing plates having constant quality can be obtained and the running cost can be greatly reduced. |
