リス現像に関する研究 (第1報)

リス効果の考察

抄録

The lith developer is alkaline hydroquinone developer having very low concentration of free sulfite ion. When the lith type emulsion is treated in lith developer, it has a very short toe and can be developed to a very high gamma. Yule considered that the oxidation products of hydroquinone act as accelerators for lith development. James considered the oxidation of latent image by quinone.
This paper relates to the effect of bromide ion and quinone in lith developer and the mechanism of lith development.
The experiments showed;
1. When commercial lithfilms were developed in the sulfite free hydroquinone developer containing no bromide ion, the lith effect disappeared completely.
2. Among the substances whose silver salts are difficult to solve, bromide ion showed a large lith effect and thiocyanate ion showed a little lith effect.
3. The oxydation of latent image by quinone was promoted by bromide ion and at lower pH. That of metallic silver was promoted by iodide ion, bromide ion and thiocyanate ion.
4. When exposed lithfilms were immersed in oxidizing solution containing quinone and bromide ion before lithdevelopment, they showed short toe.
Redox potential of latent image seems to be about 0.1-0.2 V more negative than the potential of metallic silver.
In the presence of bromide ion the possibility of oxidation of latent image is considered.
It is presumed that good lith effect may be obtainable by balancing both of accelerating effect in the higher-exposure regions and of oxidizing effect in the lower-exposure regions.