Method of using a test film to measure developer activity

Abstract

A method of controlling developer activity in the processing of photosensitized printing plates; comprising, exposing a photographic test film, comprising, a film adapted to pass substantial amounts of light through some portions thereof and substantially lesser amounts of light through other portions thereof, preferably transparent portions and opaque portions, and having a background area and a plurality of insets separated from one another and surrounded by and separated by the background area, the background area having a plurality of regularly spaced dots, having a relatively small total dot perimeter per unit area and a constant dot size and adapted to pass substantial amounts of light through said dots, separated by lines adapted to transmit substantially lesser amounts of light through said lines, each of the insets having a plurality of regularly spaced dots, having a larger total dot perimeter than the small dot perimeter and constant dot size and adapted to pass small amounts of light through said dots, separated by lines adapted to pass substantially larger amounts of light through said lines, and the dot sizes from one inset to another differ progressively in said plurality of insets, along with a film of the material to be reproduced by said plate; establishing an inset which blends into the background area on the reproduced test film configuration on said plate when a plate is developed with a fresh developer fluid; repeating the steps of exposure and developing for subsequent plates; and adding replenisher or a diluent for said developer fluid when an inset other than said established inset blends into the background area on the reproduced test film configuration on one of the subsequent plates.