Studies on Lith Development (III)

Image Spreading Phenomenon in Lith Development

Abstract

It is well known that lith developement has a phenomenon of image spreading. Yule considered that it is due to the oxidation products of hydroquinone.
In this paper image spreading in lith development was observed and the effect of the oxidation products on lith development was investigated.
The experiments showed:
1. Image spreading in lith development disappeared by the addition of sulfite ion
2. The addition of quinone to lith developer resulted in an increase of sensitivity, but no effects were observed in the sulfite-free hydroquinone developer which contains no bromide ion.
3. The addition of siver chloride emulsion to lith developer increased the rate of development, but in the absence of bromide ion the rate decreased.
4. When bromide ion was removed from lith developer the rate of development and m aximum density increased.
These facts suggest that the oxidation products themselves are on active developing agent. Their roll in lith development probably decreases the negative charge barrier effect resulting the approach of active hydroquinone anion to promote lith development.