Strange "comet shape" over-developed streak with prescysol... any idea?

[Vania]

Hello,

I've been using Peter Hogan's Prescysol, semi-stand method, for a while now, and with much satisfaction since I switch from filtered water to demineralized water.
But coming back from a photo trip, my first 2 rolls of 120 films gave me weird overdeveloped streaks in the highlights (namely sky area) on some frames. Quite fortunately, the good ones have been spared! Nonetheless, this is quite important work to me, and I can't afford to take any risks with the rest of my film batch.
So I need to figure out precisely what is causing this, and if I can safely keep using Prescysol (which I was really counting on) for the rest of the job.

The film is tri-x. I use the standard semi-stand process @ 24°C for 10'30 with a 5 min presoak.
I rinse for 2 min in running water (I change the water 3 times with about 6 to 8 inversion each time).
I always use the same fixer with Prescysol, Berfix 2, made by Bergger specifically for pyro development, and fix for 5 min. I reuse the fixer only once (which was the case here) and add 1 min. Fixer is diluted in demineralized water.
Final rinse is 20 min, then I leave the film for 5 min in demineralized water so I don't need to use a wetting agent.

Any help trying to understand what is going on would be much appreciated, as I am totally clueless... (hope Peter Hogan is around!)
Following are some scans of the problem at hand.

Thank you all for your help.
Vania

[JimW]

That's a significant highlight in the top of the 'comet' as if one photographed a balloon with flash..... Do all the other 'comets' look similar?

[Peter Hogan]

I've spent some time examining these negs, and I can't think of any processing problem whatsoever that would result in such identical marks repeated like this. I've never seen this with any developer, let alone Prescysol! I would say it is almost certainly a fault with the film emulsion, and I would suggest sending them to Kodak for their opinion. Carry on developing, Vania!

[Vania]

Thanks Peter for taking the time to answer. The same post is on the APUG forum http://www.apug.org/forums/forum37/8...ml#post1151099 where someone suggest that there might be an issue with undisolved crystals:

Undissolved particles/crystals in the developer stuck to the emulsion. It looks like a comet around them because the developer becomes much more concentrated around the particles, and gravity forces it downwards when it slowly dissolves due to the agitation.

Even if I always check that part B is well disolved, I notice that there was some crystals on the neck of the part B bottle that could have felt undisolved in the developer... It's quite a stretch but do you think it's possible ?
If yes, someone suggested the use of coffee filters to keep the crystals out of the developer. Is this sound?
Again, thank you.

[Vania]

Sorry Jim, i didn't see your post. Yes they all look similar.

[B&W Neil]

I looks more like mechanical damage to me and it could well be a manufacturing fault. Alternatively, some damage introduced during the developing process. Check spirals, rings, fingernails and anything else that comes into contact with the film from the time you unwind the spool.

Neil.

[Peter Hogan]

The undissolved crystals idea doesn't sound credible to me. It does't make sense that dev would become more concentrated round a crystal, or anything else for that matter. Besides, the dev is at 24 degrees, and none of the components of either the A or B solution will remain solid in that temperature liquid, one of the reasons for using that temp, incidentally.
What is interesting is the identical shape and almost identical position of the marks on the neg; too coincidental for my mind.
Bear in mind also that in the many years I've been making and using this dev, some thousands of customers also, that the 'crystal' problem would surely have raised it's ugly head before now.....
I still stick with the faulty film prognosis....

[Richard Gould]

Vania, to me it looks like some form of mechanical damage to me,either a fault in the film, or damage caused to the film during the loading of the film into the spiral, maybe in the dark you caught the film with a nail,or something on your hand,maybe something on your spiral, Check your spiral, etc, Can not see it being chemical, not with developer,Richard

[JimW]

Any chance of double exposure, even during (bad) manufacture? The comet looks too sharp, too clean and too consistent for a processing fault. Drying marks tend to be variable, badly mixed chemicals don't tend to give such sharp results. And for me it still looks like a highlight on the edge of a balloon. But I am guessing here.

[Vania]

Thanks for all the contributions!
So, mechanical problem doesn't seem plausible simply because the neg has no sign of damage of any kind.
I have two last theories :

1. Could it be x-rays ? Although the films only went twice through them and only a few frames are concerned.
2. Could it be that the fixer somehow crystalized on the film ? And so when I checked the film for fog as usual only after one rinse after fixing, light could have hit those spots where the fixer has crystalized...

If not, I sure hope Peter's right! Quite a reassuring perspective given his experience...

Again thank you.
V.