Brown stains after development of underexposed B&W negatives?

[adan]

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On 1/30/2022 at 5:54 AM, LocalHero1953 said:

I started with Ilford Rapid Fixer, which suggests a wide 2-5 minutes range

I use "twice the clearing time," which even with fresh Rapid Fix is generally 4 minutes (2 minutes x 2). But even longer is fine - "overfixing" isn't a thing until one gets to 20 minutes or longer.

Don't stint the fixing - and don't rush it!

I'd also note that the tight structure of Delta/T-grains usually requires more fixing than old-school cubic-grain (HP5+, Tri-X) films. Delta/T-grain can easily take up to 2 minutes just to clear the milkiness (which is the "halfway-fixed" point).

So I'm in the "inadequate fixing camp" also - left-over silver halide not removed from the film turns yellow or brown or gray once exposed to room light.

And, yeah - underexposed film will have more unexposed silver-halide to remove (and therefore take longer) - and the thin negs will make the remaining stain more obvious.

Oh, and yes - agitation can "pump" chemicals through the sprocket holes, leading to either differential development or differential fixing in line with the holes. With any kind of tank, keep the agitation gentle, delicate, slow and smooth. You're not trying to beat the image (or the excess silver-halide) out of the film with a stick - simply gently moving the chemistry in touch with the silver away from the film and replacing it with fresher dev/fix every so often.

And one more - guess what's functioning drops way off at about 18°C?

That's right - fixer.  Which is why 20° C is the lowest recommended processing temperature. If your fixer is just a little bit chilled by the ambient storage temperature, it may need a warming bath before using.

Edited February 13, 2022 by adan

[PCPix]

It’s a fix problem. I looked at some negs I processed at school in 78... they had exactly these brown stains. Re-fixed and washed - voila. 

[LocalHero1953]

I’ve had no recurrence since increasing the fix time!

[Ouroboros]

On 3/17/2022 at 7:43 PM, LocalHero1953 said:

I’ve had no recurrence since increasing the fix time!

Apologies if this has already been suggested, I haven't read the entire thread; check your fix for exhaustion regularly by snipping a film leader and 'fixing' it, taking a note of how long it takes to clear.  My experience is that Rapid Fix can  often go from usable to brown staining negatives quite quickly.

 

[LocalHero1953]

1 hour ago, Ouroboros said:

Apologies if this has already been suggested, I haven't read the entire thread; check your fix for exhaustion regularly by snipping a film leader and 'fixing' it, taking a note of how long it takes to clear.  My experience is that Rapid Fix can  often go from usable to brown staining negatives quite quickly.

 

Thank you - I think @250swbsuggested it, and I've been doing that ever since. A neat solution.

[davidmknoble]

Old thread, but I found it because I had a few brown streaks, suspected the fixer and just wanted to confirm.

I’ll add that the Ilford washing method that @LocalHero1953 indicated near the beginning (5 agitations, 10, 20) saves a significant amount of water, but I also use an archival rinse which sits for 2 minutes in-between fixing and washing.  That cleans out a lot of chemical and then the Ilford method finishes it off with less water.  I actually found some negatives from 1984 last weekend and they were as clean as the day I developed them - so that’s a 40 year test!