Abstract

Silicic acid is a water soluble colloidal resin which can be obtained commercially. The effect of silicic acid as a desensitizer in fountain solution was studied. The resin of this colloidal solution was compared to gum arabic solution. The study included the investigation of the physical properties of the solution at different concentrations as well as press performance. Comparisons were drawn regarding wettability, viscosity, surface tension, dot size change, minimum dampening rate to clean-up the non-image areas, resolution, resistance to scum, blinding of image areas, rate of de-inking over- run non-image areas, performance distinction between lithium silicate and sodium silicate, and changes with aging in solubility properties of silicates in fountain solutions. The experiments were carried out under carefully controlled conditions; the only variable present was one ingredient of the fountain solution. The concentration of the necessary solution was determined. The effect of concentration was discussed and reported. A considerable number of the results were statistically analyzed by the two factor analysis of variance. The effectiveness of silicic acid solution as a substitute for gum arabic solution varied. Silicic acid is comparable in regard to the ability of the solution to clean the plate with minimum number of sheets, resistance to scum, resolution, and blinding of image areas. Performance distinctions between lithium silicate and sodium silicate and solubility properties of silicates with aging were noted. Gum arabic produces smaller changes in dot size and does not blind images as quickly as silicic acid does. The advantages of silicic acid are good resistance to bacterial attack, longer shelf life, and better wetting of the plate than gum arabic when properly diluted.

Library of Congress Subject Headings

Silicic acid; Photography--Printing processes--Gum-bichromate; Offset printing

Publication Date

5-1-1977

Document Type

Thesis

Department, Program, or Center

School of Photographic Arts and Sciences (CIAS)

Advisor

Silver, Julius

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TR445 .A45

Campus

RIT – Main Campus

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