Fundamentals of Single-Solution Etching in Gravure.

One of the time-consuming, variation-causing aspects of preparing gravure cylinders is the use of several etching solutions of various densities. It is doubtful that a carefully controlled, mechanical or automatic etching operation could be designed around the use of this many-solution etching process. However, research has shown that the number of etching solutions can be reduced to one and that a time-scale can be established to perform the etching step in the preparation of gravure cylinders. This improvement is based on research that developed methods for, (1) careful control of the dichromate sensitizing of the light-sensitive paper, (2) new light exposures that modify screen and continuous-tone exposures, (3) control of the effect of varying composition of the etchant on the resist, and (4) adaption of the particular type of dot process that is used. Data for exposures of the sensitive film related to curves for results in terms of positive density and print density show that the procedure must be varied with each type of process. Further development of the techniques that are explained could lead to electronic control of cylinder preparation.