Studies on the Lith Development of a Silver Iodobromide Emulsion

The lithographic development of a silver iodobromide emulsion with thiocyanate substituted for bromide in a lith developer formulation showed differences in behavior with regard to induction time and maximum rate of development at equal levels of normality. An experiment was designed with development time, halide concentration, and exposure level as the variables with maximum rate of development, time to reach 0.20 optical density (induction time), and slope at 0.40 optical density as the response parameters. The maximum rate of development with the developer containing bromide was found to be significantly dependent upon exposure level and not significantly dependent upon bromide concentration in the range of 0.020 N to 0.058 N. Significant different exists between 0.000 N and all other levels of bromide. The maximum rate of development with developer containing thiocyanate was found not to be significantly dependent upon thiocyanate concentration nor exposure level. Induction time with the developer containing bromide is significantly dependent upon exposure level and not statistically dependent upon bromide concentration. Induction time with the developer containing thiocyanate is very significantly dependent upon thiocyanate concentration and exposure level. Slope at 0.40 optical density with the developer containing bromide is independent of bromide concentration from 0.020 N to 0.058 N and development time from 1.0 to 2.5 minutes. Slope at 0.40 density with the developer containing thiocyanate is independent of development time. Thiocyanate concentration is highly significant with the 0.000 N and 0.063 N levels as one population and the 0.021 N and 0.042 N levels as another population