Well, all I can say Charlie is that your experience is completely at odds with my own, and with all known facts about the behaviour of gelatine in acid and alkali solutions.(posted 8636 days ago)
I used to carry out precision copy work on both Lith and continuous tone film, from 10x8 up to 20x16 sheets, which had to be dish developed.
Those times when I didn't wear surgical gloves, I could feel the emulsion softening in the developer, and immediately hardening up in the acid stop bath. After it had been in the fixer for a couple of minutes, it was very abrasion resistant.Another thing that wories me about TF4 is that it's claimed to be 'archival quality'. How do they know?
Here's my own empirical evidence: I have a personl collection of negatives, in formats from 35mm to 5x4, going back more than 30 years. I've always used an acid hardening-fixing bath. None of those negatives show the slightest sign of chemical deterioration or damage. Not even a detectable change of image colour. Not even on films that were just done as a quick test, where the fixing and washing time were shortened.
However, two complete 35mm films have been lost to fungal attack, and suspiciously, they were processed in chemicals that weren't directly under my supervision. I suspect that the difference may be that the fixer didn't contain any hardener, since they were given my usual wash time.
The storage conditions for the mouldy negs has been exactly the same as the others; in fact they were in the middle of a ring binder of glassine envelopes, sandwiched between perfectly good film.Acid hardening fixer has been around a long time, and its results have stood the test of time. TF4 hasn't.