TF4 issue/question

[George Collier]

I have been using TF4 exclusively for a while, film and prints. I keep a separate bottle for film.
I had a slightly used gallon (used for prints), and added another fresh gallon to it to print some 16x20's (8 final prints with assorted test strips). The paper was Forte V and the developer was LPD 1:2.
I rinse in running water for a minute or a bit longer (a tray with holes in one side, propped up on the other side, running water).
I fix for a minute to a minute and a half. In the end, the fixer tested good (Edwal hypo test), and in the end, the prints toned fine with selenium, but the fixer had little black granules in it, some small enough to get through a filter funnel filter.
I've seen it before in this fixer, but I think only with prints. Does anyone know what this is? I've not seen it before with conventional acid fixers.

 

[Tom Hoskinson]

You may be carrying some oxidized developer residues over into your fixer.

How does your used developer look? See any black particulates? You might try filtering it.

Do you use a running water rinse after devlopment or do you use a stop bath?

 

[Ryuji]

That's nothing to worry about, and the dark stuff is dyestuff and other diffusible emulsion additives that got washed off during fixation. The stuff came off and gets aggregated. If you stir up the solution, the "granules" you see will break up and they will go through filters very easily. More commonly, the stuff makes a sort of thin, broken "sheet" at the bottom of the bottle. If the gunk bothers you, it's easier to decant off, but don't worry, the stuff won't stick to emulsion surface and can be easily washed. This happens with almost any fixer, but may be more visible in neutral and alkaline fixers.