x-ray
Veteran
But ISO speeds fall by about 1 stop for the same reason. (Basis: Ilford research.)
Cheers,
R.
I've never experienced a speed drop and have been replenishing both dip and dunk hand lines, gas burst and continuous processors for forty five years. Every line I've replenished Ive run controll strips to monitor it. If this were the case every processing machine running E6 and B&W would start to lose speed as its replenished. The 1st developer in E6 is basically an MQ developer just like traditional B&W film developers so if an ISO drop was normal then You'd never know what ISO to rate your E6 at or your B&W film for that matter. You might build up enough byproducts to cause this if you replenish behing the recommender volume 1gal repl/1gal working strength but I can't say because I've considered my work to be too valuable to risk problems.
Under utilization of a processing line will cause oxidation and speed loss. Oxidation is not only a byproduct of air and developer it's the chemical reaction that makes film process. Reduction of the silver halide into metallic silver causes oxidation of the developing components. This will occur in the presence of oxygen or without oxygen. It's an ion exchange process that causes this REDOX reaction. These components that are oxidized are what the replenisher adds back without adding additional bromide or sulfite. All of the components are maintained at the proper concentration if replenished and monitored properly. Only what's depleted is added back to maintain activity. My degree is in chemistry and microbiology and did a research paper on the process.