The present study arose out of a desire to test the assumption that in order to obtain direct stencils with good edge definition, one either had to use fine screens or. If using a relatively coarse screen, apply multiple coatings of emulsion to the screen before making the stencil. Neither alternative seemed satisfactory, since the first did not allow optimal use of the scope of screens available, and the second entailed an expenditure of time and supplies that could possibly be shown to be unnecessary. It was therefore determined to carry on an experiment that would show whether direct stencils with good edge definition can be obtained on relatively coarse screens with only one, or at most two applications of emulsion. The experiment thus envisioned also provided an opportunity to observe the influence on two other factors on stencil edge definition, besides those of mesh count and emulsion thickness: namely, screen thread diameter and coater blade thick ness. What finally evolved was a three-factor, three-levelled factorial experiment, in which the variables under study were* screen mesh count, thread diameter and emulsion thick ness. The fourth factor came into play when the experiment was run once for emulsions applied with a thick-bladed coater, and once for those applied with a thin-bladed coater. The specific question under study was: in the direct stencil system, is there a difference in the quality of edge definition obtainable with variations in screen mesh count, screen thread diameter, coater blade thickness and the number of emulsion coatings applied? Eighteen screens were stretched expressly for the experiment, representing three different mesh counts and three different thread diameters for each mesh count. Each screen was prepared in such a way as to receive three stencils of varying thickness per screen. All stencils were exposed to a test target designed to allow for the observation of diagonal and parallel stencil edges (i.e., diagonal or parallel with relation to screen thread direction). After the stencils were made, they were visually inspected, and the data obtained thereby was subjected to an analysis of variance. The results obtained showed that of the four factors studied, mesh count was the only one that made a clear difference in the quality of stencil edge definition. What the experiment did not conclusively show was whether or not coater blade thickness had any influence on that quality. Nevertheless, what is perhaps of greater significance to the printer in Industry Is that the experiment did show that on a coarse screen a stencil with good parallel edge definition could be obtained with only one coating of emulsion (as one coating was defined in the experiment).
Library of Congress Subject Headings
Stencil work; Screen process printing
Department, Program, or Center
School of Media Sciences (CIAS)
Bedirian, George, "A study of the effect on direct stencil edge definition of emulsion thickness, screen mesh count, fabric thread thickness and coater blade thickness" (1977). Thesis. Rochester Institute of Technology. Accessed from
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