Mottle like marks HP5+ frame only

So this is odd. The whole roll appears affected, this was bulk rolled from a 100 foot spool in my usual manner into a plastic cassette. Camera used was Praktica BX20S with a Carl Zeiss Flektogon lens. There is what looks like mottling at the top of the frame. BUT it only appears in the frame, not in the rebate area and not between frames. Also the edge markings came out fine so I doubt it's a processing problem. For the record I used Ilford ID-11 stock. A roll of FP4+ which I processed in the same tank at the same time came out beautiful.

It strikes me this happened in the camera. Any ideas what could cause this? I last used the camera a couple of months ago and everything was fine. I replaced the foam seals last year so weird light leaks are unlikely

Am I right in assuming that the FP4 roll was at the bottom of the tank? Perhaps you also noticed some foaming? And while we are at it, how much developer did you use and what is the minimum for the tank you used?

I agree this looks like heavy foaming of the developer. Just wash spirals and tank thoroughly after using a wetting agent and don't overagitate.

I wasn't aware of foaming but that would make sense. I was using my usual Jobo tank but I agree it looks like a foaming issue. My developer is also nearing the end of it's life so the volume might be on the tight side. I was certain there was sufficient left but....I do agree with the diagnosis. Thanks for the advice.

I'm going to do a single roll of Rollei Retro 400S in the same developer and tank before making up new developer. The results will be interesting. If it's a foaming issue then one roll of the 400S should be fine.

Just to update people, I developed a single roll of Rollei Retro 400S in the same tank with the same developer, being careful not to invert "violently" and everything was fine. Likely the volume of developer was marginal for two films and despite 30 years experience, my agitation technique may not be perfect.

Agulliver, I have used Xtol almost always at 1+1 for several years now as my "go-to" developer. Like you, I also use a Jobo tank and this has a wide top for the movement of developer when you invert. As Xtol is a Kodak developer I follow the Kodak agitation regime which involves 2-3 inversions every 30 secs. Add those factors together gives me foam in the top of the tank every time but I have yet to experience any problems such as you seem to have here.

I cannot say that what you have isn't the result of foaming, nor unfortunately can I say what it might be but my foaming so far hasn't resulted in your problems so can there be another cause besides foaming?

If you have been agitating for 30 years without problems then it strikes me as incredible bad luck that suddenly foaming is the cause. Do you use wetting agent in the tank post processing without rinsing the tank thoroughly afterwards and what is your agitation regime?

pentaxuser

@pentaxuser that is possible, there might have been some wetting agent remaining in the water that I washed the tank in after processing. It's not "normal" with my MO but it's possible as I process film in the bathroom with one sink.

All food for thought in honing my technique. I didn't notice it foaming but to be totally honest I wasn't looking. I agree that the marks on the negatives look like the results of foaming. Fortunately they are in the sky area and I was able to edit them out and get reasonable results....enough for sharing the scenes with the friends who were there.