What happened to my Pyrocat?
Hi everyone...heh, my first post here after much lurking...
Until yesterday I've been very happy with the negatives from my home-mixed Pyrocat, and was thinking it could become my main developer. My original 100 ml batch, now 2 months old, is about 2/3 gone, and I've been processing some film every weekend for the last few weeks with some really great results. Yesterday, however, my Pyrocat experience suddenly took a turn for the worse.... I shot some 4x5 Classic 200, exposing it at ISO 100 and processing it in my Jobo (1:1:100) as I've been doing, and every one of my negatives looks severly underexposed! The shadow areas are beautifully clear, and there's hardly even any midtone density, but the highlight areas are quite dense....it's as if the film took a sudden dive in effective speed. After racking my brains trying to figure out whether the problem is equipment or exposure related, I came to the conclusion that it must be the developer. So today I shot some test negatives of a contrasty sunlit scene, all at the same exposure, and developed one in Pyrocat and the other in Xtol. The Pyrocat negative has the same look of severe underexposure, while Xtol produced a full negative, consistent with the metering technique I've been using all along.
So what happened to my Pyrocat? One possibility that occurred to me is that the phenidone in the part A has conked out. If I've got the concept right, phenidone is usually superadditive with a second developing agent in a developer, in this case catechol. My negatives still show a brown stain, implying that the catechol is still doing some work, but without the kick of the phenidone, it's only active enough to develop the highlights. Since I mixed the stock solutions using spoon measurements, I'm wondering if I had too little phenidone...enough for the developer to work for a while, but too little to resist decay in the slowly emtying glass bottle. Come to think of it, the diluted solution doesn't have the pinkish or tan color it may have had originally....but I'm not sure.
Do these conclusions make sense to anyone, or has anyone had a similar experience? I keep the solutions in 100ml brown glass bottles, but are there better storage ideas?
Thanks for any ideas....