Lith developers, unlike conventional developers, lose alkalinity when aerially oxidized. This is attributed to the alkaline reaction of the formaldehyde-bisulfite compound (FBS) commonly employed in lith developers as a "sulfite buffer". Conventional chemical analysis methods are used to obtain data and experimentally derive an equilibrium constant for the alkaline disassociation of FBS. Chemical and sensitometric data are presented that indicate that the alkalinity loss contributes significantly to the overall loss of developer activity. It is also shown that aeriating a lith developer quantitatively converts hydroquinone to hydroquinone monosulfonate that, in turn, is a measurably active developing agent. Additional data are presented that show that solution ionic strength strongly influences hydroquinone developer activity. This is attributed to increased ionization of hydroquinone. Finally, chemical analysis data are given that indicate that the accepted reaction for the aerial oxidation of conventional hydroquinone developers does not quantitatively apply when the sulfite concentration is in the range commonly employed in lith developers.
Library of Congress Subject Headings
Photography--Developing and developers
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Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Smith, Joe, "Aerial Oxidation of Lith Developers" (1969). Thesis. Rochester Institute of Technology. Accessed from
RIT – Main Campus