Thomas Gribb


The photographic and physical properties of viscous lith developers have been investigated. Developers thickened with hydroxyethylcellulose (Hercules Natrasol 250 HR) afforded the optimum characteristics of ease of mixing and pseudoplastic behavior. Photographically, viscous lith developers demonstrate performance in many ways similar to non-viscous formulas. Characteristically, the developers show great sensitivity to changes in pH, and changes in HQ, bromide, and sulfite concentrations. However, viscous lith developers are inherently 0.2 log H lower in photographic activity than comparable non-viscous developers. Furthermore, viscous developers are characterized by low contrast in highlight (negative) areas of halftone reproduction. Large dot area (90%) images show poor dot quality. The lower activity is easily compensated for by changes in time and/or temperature. Also, with adjustments in constituent concentrations, the dot quality may be improved. However, no method was found to regain halftone reproduction contrast. Changes in viscosity per se impart no photographic effects. The photographic dissimilarities between viscous and nonviscous lith formulas are caused by agitation differences. This is demonstrated using still development techniques with non-viscous developer.

Library of Congress Subject Headings

Photography--Developing and developers

Publication Date


Document Type


Department, Program, or Center

School of Photographic Arts and Sciences (CIAS)


Carroll, Burt


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