High density line in 120 negatives

argent_negre · Thursday at 12:35 PM

Dear all,

I have the following problem with some frames when developing 120 film. I think I know its cause, but I haven't been able to
find a solution. I would like to know if any of you has also had the same problem and have been able to overcome it.

The problem is easy to spot. In the attached imaged, there is a line of higher density, strong enough to spoil the image.

Let me describle the set-up:

- film developed in Jobo 15xx series tank, by inversion (one minute of constant agitation and two inversions every 30sec),
- two rolls in a spiral,
- film is inserted in the spiral with the emulsion facing inside,
- it happens only in at most one frame in a roll, the second one
starting from the part of the roll closest to the center column,
but I am not sure if it corresponds to the first or the second roll
in the spiral (probably the second),
- the problem is developer independent.

I think that the cause is the following: when a roll is inserted in the spiral, its end has a strongest curl.
When the second film is inserted, a part of it lies on top of the curl of the first one. On this part, the developer
flows faster than on the rest of the film, thus creating the density line.

My agitation pattern is rather slow, but I bang the tank against the counter with two or three strong blows, otherwise
I have problems with bubbles.

I will appreciate any help you can get me.

Best regards,
Pau

Sharktooth · Thursday at 1:36 PM

I have some Jobo tanks and reels, but I'm not sure if any are of the 15xx series. On the ones I have, there are red plastic tabs on the outside face of the reel that act as stops so that the second roll can't overlap the first roll. You pull these stops out when you're loading the first roll, and when it's loaded fully past the stop point you can push the tabs back in. Now when you load the second roll the red tab stop prevents the second roll from going in too far, so it won't overlap the first roll.

Although your scenario is plausible, I'm still dubious that this would cause the problem shown. I don't have a better explanation, however.

grahamp · Thursday at 2:10 PM

"
- it happens only in at most one frame in a roll, the second one
starting from the part of the roll closest to the center column,
"
Since you show a high frame number in the example, are you loading the film in starting at frame 1 or the last frame? It sounds like you take the film off the backing paper, and load that end (frame 1) first?

This would determine (if it is an overlap artefact) which film is affected.

argent_negre · Thursday at 2:14 PM

Sharktooth said:
I have some Jobo tanks and reels, but I'm not sure if any are of the 15xx series. On the ones I have, there are red plastic tabs on the outside face of the reel that act as stops so that the second roll can't overlap the first roll. You pull these stops out when you're loading the first roll, and when it's loaded fully past the stop point you can push the tabs back in. Now when you load the second roll the red tab stop prevents the second roll from going in too far, so it won't overlap the first roll.

Although your scenario is plausible, I'm still dubious that this would cause the problem shown. I don't have a better explanation, however.

I do use the red tabs to avoid overlaping the films. The films do not touch each other. In that case, the result would be completely different. In the image I've shown, which is low in contrast, the phenomenon is more pronounced. Additionally, today I was developing at 24 degrees celsius, which may have accentuated the effect.

John Wiegerink · Thursday at 2:16 PM

What camera/back are you using? Dark slide light leak????

argent_negre · Thursday at 2:17 PM

grahamp said:
"
- it happens only in at most one frame in a roll, the second one
starting from the part of the roll closest to the center column,
"
Since you show a high frame number in the example, are you loading the film in starting at frame 1 or the last frame? It sounds like you take the film off the backing paper, and load that end (frame 1) first?

This would determine (if it is an overlap artefact) which film is affected.

I start loading the film from the last frame, directly into the spool.

argent_negre · Thursday at 2:18 PM

John Wiegerink said:
What camera/back are you using? Dark slide light leak????

In this case, it was a Plaubel Makina 67, but the problem is camera independent. It is certainly not a light leak.

argent_negre · 2025-08-22T02:44:22-0400

I've just found this thread, describing a similar problem.

Also, some people advise loading only one 120 roll in each spool,
to avoid potential problems. I know that the problem only appears
when loading two rolls.

Does anybody successfully develope 120 film loading two rolls in
a spool in a 15xx Jobo tank?

koraks · 2025-08-22T03:11:02-0400

I've only ever processed a single roll of 120 at a time in my 1520 tank. This yields perfect results.
I can't explain your high-density anomaly. It honestly doesn't look like a flow or surge mark related to the liquid dynamics of the developer. Those tend to show up differently, e.g. as surge marks along the edges of the film that suggest interaction with the film reels, or as somewhat sharply defined 'running droplet' marks due to slow or uneven pour-in of the developer. I don't quite see how the edge of one roll of film pointing inward into the reel would cause uneven development on the other roll, since the emulsion faces inward with the film loaded onto the reel.

250swb · 2025-08-22T03:33:31-0400

Is it a camera stress mark? For example would that part of the film have been resting on one of the rollers in the camera for any length of time, especially in hot weather?

argent_negre · 2025-08-22T04:18:43-0400

250swb said:
Is it a camera stress mark? For example would that part of the film have been resting on one of the rollers in the camera for any length of time, especially in hot weather?

I don't think so. The marks appear in a position that only depends on the developing tank. In the past, I've seen them coming from several different cameras, shot in diffferent ways.

argent_negre · 2025-08-22T04:40:27-0400

koraks said:
I've only ever processed a single roll of 120 at a time in my 1520 tank. This yields perfect results.
I can't explain your high-density anomaly. It honestly doesn't look like a flow or surge mark related to the liquid dynamics of the developer. Those tend to show up differently, e.g. as surge marks along the edges of the film that suggest interaction with the film reels, or as somewhat sharply defined 'running droplet' marks due to slow or uneven pour-in of the developer. I don't quite see how the edge of one roll of film pointing inward into the reel would cause uneven development on the other roll, since the emulsion faces inward with the film loaded onto the reel.

When I process a single roll, my results are also perfect.

My hypothesis is based in the following:

1) I have observed, loading two rolls in daylight, that the distance between each loop of the films (facing inwards) is constant everwhere, except a at the point where the curl of the inner film increases at the end on the film. There, the distance is smaller, along a very precise vertical line (vertical in the tank).

2) The continuity equation of incompressible fluids states that the speed of a fluid in a channel increases when the channel becomes narrower, so I'm guessing that the developer may go faster in that particular area of the outer film (whose emulsion side is facing inwards). Different speeds may account for different densities on film.

Of course, this is only a hypothesis. Using very gentle inversions (to decrease the speed of the developer in the tank) seemed to improve the results (but I am not sure). In this last case, I processed the film at 24 degrees Celsius, instead of my usual 20 degrees, cutting down the time. The shorter developing time may have had some impact in the unevennes.

Anyway, I was reaching out trying to find someone with the same problem and a solution.

Thanks to all contributors,
Pau

argent_negre · 2025-08-22T05:11:08-0400

Here there is a picture of how the inner film is curled in the spiral (just trying to support my claim).

koraks · 2025-08-22T05:55:52-0400

argent_negre said:
Here there is a picture of how the inner film is curled in the spiral (just trying to support my claim).

Yes, I was thinking about exactly that. But as I said before, I'm puzzled how that would result in a density anomaly on the emulsion side of the film, which is facing inward, so it's on the opposite side of the film from the inward curl.

argent_negre · 2025-08-22T06:03:07-0400

koraks said:
Yes, I was thinking about exactly that. But as I said before, I'm puzzled how that would result in a density anomaly on the emulsion side of the film, which is facing inward, so it's on the opposite side of the film from the inward curl.

The extra density happens on the other roll of film, the one on top of the curl, whose emulsion is facing inward. It's the one that would be receiving faster developer speeds.

koraks · 2025-08-22T06:05:36-0400

Oh, I see, sorry for my confusion. Well, in that case I can see your point and I'd agree that this is probably a good explanation!

pentaxuser · 2025-08-22T09:14:33-0400

argent_negre said:
When I process a single roll, my results are also perfect.

My hypothesis is based in the following:

1) I have observed, loading two rolls in daylight, that the distance between each loop of the films (facing inwards) is constant everwhere, except a at the point where the curl of the inner film increases at the end on the film. There, the distance is smaller, along a very precise vertical line (vertical in the tank).

2) The continuity equation of incompressible fluids states that the speed of a fluid in a channel increases when the channel becomes narrower, so I'm guessing that the developer may go faster in that particular area of the outer film (whose emulsion side is facing inwards). Different speeds may account for different densities on film.

Pau

I wonder why such an effect isn't reported by others who do load 2 films onto reels as all films would produce the effect of an increased in curl at the end of the film?

Or have I misunderstood what you are saying?

Thanks

pentaxuser
pentaxuser

argent_negre · 2025-08-22T09:53:02-0400

pentaxuser said:
I wonder why such an effect isn't reported by others who do load 2 films onto reels as all films would produce the effect of an increased in curl at the end of the film?

Or have I misunderstood what you are saying?

Thanks

pentaxuser
pentaxuser

I agree with you. However, what I think is the same problem is mentioned in this thread. No solution, though.

High density line in 120 negatives

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