A Simplified Approach to Gum Coating Stencils.

This article describes a study of deep-etch coatings which was made in connection with their use in preparing Lithure bimetal plates. The results are presented in the belief that they will be found useful by Lithographers in the use of gum coating generally. The effect of variables on the thickness of coating is evaluated and those variables which must be controlled are specified. The effect of temperature and humidity on the combined exposure and development steps have been determined and are presented in the form of an exposure calculator. By use of this calculator, it is possible to develop deep-etch coatings similarly to photographic materials by using a standard developing time. This should improve the reproducibility of lithographic plates and reduce the number of rejected plates.