Studies on P-Q Photographic Monobaths (XII)

An Approach to the Kinetics of Monobath Processing

Abstract

A kinetic equation representing combined developing and fixing solution has been devised and experimentally substantiated.
It is known that the rate of development under some conditions approximately follows a simple first-order equation. The rate of fixation does not generally follow a simple equation as it is governed by physical process, such as diffusion. However, it was found that the rate of fixation in some monobaths conforms apparently to a simple first-order equation owing to the diffusion effect of non-charged developing agents. In such monobaths, the rates of development and fixation were found to be also conform at higher exposure level to a first-order equation as follows, but not at lower exposure level. Development; dx/d (t-t₀) =K (M-x)
Fixation; dy/d (t-t₀) =K (A-M-y)
where t=time at a given stage of processing
t₀=initiation period of development
x=developed silver at some time, t
y=fixed silver at some time, t
K=rate constant of monobath processing
M=silver obtained in time at which silver growth ceases
A=silver in film