Artefacts of bromide drag?

[Elmarc]

That’s right, agitation should be turbulent and random. This is gentle and consistent. I think even when the film dips, the rotation is so smooth that the laminar layer isn’t disturbed.

Thank you for your input Bill.
I think your previous diagnosis could certainly be the case but...if agitation should be 'turbulent and random' where does that leave the Jobo rotary process?
Please excuse me if I am wrong but i think the Rodinax and Jobo tanks work on the same principle. If the laminar layer isn't disturbed surely that would invite inconsistencies on a regular basis? Or am I missing something?

 

[Elmarc]

@Andrew O'Neill is right about Bromide Drag. This case is the flow of fresh developer into an adjacent area accelerating development.

Bromide slows development, as is well known based on how many comments in this thread point out.

The classic reason is no agitation (stand) and a textbook example is white billboard type on a gray background. The gray background would print with dark streaks.

View attachment 346748

The example here looks identical to what I am experiencing. Thank you for sharing. However this is a result of lack of or no agitation. So I am presuming that these artefacts are also possible with constant agitation. Correct?

 

[pentaxuser]

Thank you for your input Bill.
I think your previous diagnosis could certainly be the case but...if agitation should be 'turbulent and random' where does that leave the Jobo rotary process?
Please excuse me if I am wrong but i think the Rodinax and Jobo tanks work on the same principle.

First question that sprung to my mind as well as the fact that we have a number of members here using Jobo rotary processors with success. Finally that leaves the question of why it doesn't give the same problem with C41 films

Is the speed of Rondinax agitation not enough compared to Jobo assuming that Bill is saying that there is a critical speed beyond which rotation gives enough turbulence I note that my Jobo reverses the direction of rotation every 3 secs which has to be pretty turbulent. What's the action of a Rondinax/Lab box tank?

I look forward to Bill's answers on this

pentaxuser

 

[Elmarc]

First question that sprung to my mind as well as the fact that we have a number of members here using Jobo rotary processors with success. Finally that leaves the question of why it doesn't give the same problem with C41 films

Is the speed of Rondinax agitation not enough compared to Jobo assuming that Bill is saying that there is a critical speed beyond which rotation gives enough turbulence I note that my Jobo reverses the direction of rotation every 3 secs which has to be pretty turbulent. What's the action of a Rondinax/Lab box tank?

I look forward to Bill's answers on this

pentaxuser

The action of the Rondinax is in one direction only. I believe that there are some Jobo tanks that same ie: not bi-directional. Obviously, being manual, the rpm can be whatever one wants it to be within reason. An earlier poster settled on 40rpm with success. I'm not sure how he measured the speed but I am certainly in that region. The Agfa Rodinax manual recommends 1/2 turn with a slight jerking movement every two seconds for what its worth. I presume the jerking movement is to dislodge/dissipate any spent developer.

 

[Kino]

(not Bill, but I will inject this and leave it alone after this)

These all fall under the category of "directional effects" which can entail both bromide drag and other processing defects whereby either a uniform movement of developer flows over a negative without disruption (even with rotation in a bath) or developer byproducts "flow" from an area of high density toward an area of low to no density (as in stand developing).

Rotation in one direction without reversing creates laminar flow issues.

Stand developing creates issues of more energy/movement over dense areas, with the accompanying "fall" of exhaused byproducts of development toward the bottom of the tank over whatever lies below the dense areas.

That's why as a GENERAL rule randomized agitation is preferred over just rotation or a linear motion through a developer bath for consistent overall development. As with any general rule, there are exceptions and instances where this is not a problem with typical exposures.

Faults with the the above means of agitation or lack thereof, only appear under certain circumstances.

Anyway, I am done.

 

[pentaxuser]

The action of the Rondinax is in one direction only. I believe that there are some Jobo tanks that same ie: not bi-directional. Obviously, being manual, the rpm can be whatever one wants it to be within reason. An earlier poster settled on 40rpm with success. I'm not sure how he measured the speed but I am certainly in that region. The Agfa Rodinax manual recommends 1/2 turn with a slight jerking movement every two seconds for what its worth. I presume the jerking movement is to dislodge/dissipate any spent developer.

Thanks If the Rondinax introduces the agitation you mention this fairly frequent jerk would seem to introduce quite a bit of turbulence. If it is a regular jerk however then maybe this isn't random enough

Some might say the same of me in terms of a description

pentaxuser

 

[Nicholas Lindan]

Bromide, in a developer, is a restrainer. When film is developed the crystals of silver bromide are turned to metalic silver, releasing bromide into the developer. If there is no agitation the bromide laden developer from the highlight regions sinks - this developer has less activity both from extra bromide and from developer exhaustion. Chloride and iodide ions are also released in development and they also act as restrainers and add to the 'drag'. The effect is subtle and if you aren't looking for it you probably wouldn't notice it.

To get drag the film must be vertical in the tank and there must be no agitation.

Whatever is happening to the OP's film, it is not bromide drag.

 

[Elmarc]

(not Bill, but I will inject this and leave it alone after this)

These all fall under the category of "directional effects" which can entail both bromide drag and other processing defects whereby either a uniform movement of developer flows over a negative without disruption (even with rotation in a bath) or developer byproducts "flow" from an area of high density toward an area of low to no density (as in stand developing).

Rotation in one direction without reversing creates laminar flow issues.

Stand developing creates issues of more energy/movement over dense areas, with the accompanying "fall" of exhaused byproducts of development toward the bottom of the tank over whatever lies below the dense areas.

That's why as a GENERAL rule randomized agitation is preferred over just rotation or a linear motion through a developer bath for consistent overall development. As with any general rule, there are exceptions and instances where this is not a problem with typical exposures.

Faults with the the above means of agitation or lack thereof, only appear under certain circumstances.

Anyway, I am done.

Thank you Kino. Very concise and eloquently put.
I very much appreciate your contribution.

 

[Elmarc]

To get drag the film must be vertical in the tank and there must be no agitation.

The former is the case but the latter not.

 

[L Gebhardt]

Thank you for your input Bill.
I think your previous diagnosis could certainly be the case but...if agitation should be 'turbulent and random' where does that leave the Jobo rotary process?
Please excuse me if I am wrong but i think the Rodinax and Jobo tanks work on the same principle. If the laminar layer isn't disturbed surely that would invite inconsistencies on a regular basis? Or am I missing something?

The Jobo tanks have very fast moving fluid over all parts of the film even when running at slower speeds. The moving reel in the roll film tanks create a lot of turbulence and must lift a lot of developer as the reel exits the developer when it turns. I haven't used the type of processor you are using so I may have the workings wrong in my head, but it sounds like the film itself is just smoothly flowing through the developer and remaining out of the liquid for long stretches of time, especially the ends of the roll. That's significantly different from the Jobo where the used local developer is quickly mixed back in, or manual tanks where the film remains under the developer the whole time and diffusion can help as long as agitation isn't too infrequent.

If Bill's explanation is correct, and it sounds likely to me, then a faster movement through the machine should significantly minimize the issue. This would be most important early in the development since that's when the bulk of it takes place.

 

[Elmarc]

The Jobo tanks have very fast moving fluid over all parts of the film even when running at slower speeds. The moving reel in the roll film tanks create a lot of turbulence and must lift a lot of developer as the reel exits the developer when it turns. I haven't used the type of processor you are using so I may have the workings wrong in my head, but it sounds like the film itself is just smoothly flowing through the developer and remaining out of the liquid for long stretches of time, especially the ends of the roll. That's significantly different from the Jobo where the used local developer is quickly mixed back in, or manual tanks where the film remains under the developer the whole time and diffusion can help as long as agitation isn't too infrequent.

If Bill's explanation is correct, and it sounds likely to me, then a faster movement through the machine should significantly minimize the issue. This would be most important early in the development since that's when the bulk of it takes place.

The film is not out of the developer for long periods of time. Agfa ( the makers of the Rondinax) specify 1/2 a turn every two seconds. So the film is only out of the developer for two seconds (or less, if one decides to rotate faster) at any one time.
As previously mentioned the turns should be of a jerky nature. This I presume is to break up the laminar flow. So, if I am not mistaken the process is not too dissimilar to the Jobo.
Theoretically, if this is indeed the problem then yes, a faster speed and more forceful approach should take care if it. The only concern with this is how the negs will appear aesthetically in regards to increased contrast (which can be adjusted by time obviously) and increased grain. Apart from these recent anomalies I have
honed the whole process to consistently produce very nice and easy to print negatives.

 

[L Gebhardt]

The film is not out of the developer for long periods of time. Agfa ( the makers of the Rondinax) specify 1/2 a turn every two seconds. So the film is only out of the developer for two seconds (or less, if one decides to rotate faster) at any one time.
As previously mentioned the turns should be of a jerky nature. This I presume is to break up the laminar flow. So, if I am not mistaken the process is not too dissimilar to the Jobo.
Theoretically, if this is indeed the problem then yes, a faster speed and more forceful approach should take care if it. The only concern with this is how the negs will appear aesthetically in regards to increased contrast (which can be adjusted by time obviously) and increased grain. Apart from these recent anomalies I have
honed the whole process to consistently produce very nice and easy to print negatives.

I should have searched first for the Rondinax as it is not working the way I thought understood it. It actually does look very similar to the Jobo reels in operation, but it appears to only rotate in one direction. Is that correct? If so that could be significant.

 

[Elmarc]

I should have searched first for the Rondinax as it is not working the way I thought understood it. It actually does look very similar to the Jobo reels in operation, but it appears to only rotate in one direction. Is that correct? If so that could be significant.

Yes that is correct. See post #79.
Are all Jobo tanks bi-directional?

 

[john_s]

It seems that I have been taking the term "bromide drag" too literally. What we're talking about here is non-homogeneity of all sorts developer and development byproducts and flow rates.

 

[MattKing]

Yes that is correct. See post #79.
Are all Jobo tanks bi-directional?

While the direction of rotation matters, it is the randomness of the fluid movement in relation to the film that really matters.
Characteristics that work together to either ensure randomness or cause repeatable patterns of flow include the direction and rotation of the rolling or inversion, the architecture of the tanks and the reels, and the mechanics and speed and direction and energy of the agitation.
I use both inversion and rotary agitation, and try to ensure that the liquid tumbles and gurgles through the film.

 

[L Gebhardt]

Yes that is correct. See post #79.
Are all Jobo tanks bi-directional?

As far as I know all Jobo processors reverse every few seconds. On one of mine you can turn the feature off, but on the automated one you can not. I suspect the rapid reversal really helps with the agitation.

 

[George Collier]

So George, you can get bromide drag with continuous agitation and if the streaks are bromide drag then is Andrew O'Neill point nonsense His point was this "Actually, I just realised that you are showing us the positives. The drag marks are lighter. Bromide drag marks should be darker in the positive (clear in the negative).

Chuckroast can you say why pre-soaking may cure the problem when the OP has never used this and has never suffered this problem before?

Something or things has.have changed but previous success would suggest that unless he has been very lucky in the past and his "winning streak" has stopped it is unlikely to be either

pentaxuser

This is a great discussion, but would be much better actually talking. Zoom, anyone?
pentaxuser - My understanding of bromide drag is that it results from unidirectional agitation, not continuous.
I understand that the posted image is positive but my comments are meant in addressing the negative, where the issue under discussion takes place.
An interesting distinction has surfaced, though - Is bromide drag about shifting stronger (fresher) developer, or moving silver (or silver halide matter?)

 

[pentaxuser]

pentaxuser - My understanding of bromide drag is that it results from unidirectional agitation, not continuous.

My understanding, based purely on the range of opinions expressed is that there is no understanding of what constitutes insufficient turbulence. Is what we call unidirectional agitation known to be a problem? Has there ever been anything resembling a scientific experiment on this? Does anyone know if rotation in one direction really results in insufficient turbulence. You'd need a transparent tank to see, wouldn't you? If the tank turning in one direction only "slices through the film" without creating any motion or only a uniform motion and therein lies the problem then when this ends and the tank reverses why does the film then experience any turbulence if there was none before? So is even a Jobo processor the right thing to use?

What is clear is that the OP's Rondinax/Lab box tank has a jerk built into to its motion so this would suggest that as a cause of his problem of what may or may not be bromide drag due to lack of developer motion this may be low on the list of likely suspects or so it seems to me

pentaxuser

 

[Kino]

All related to motion pictures, but film is film...

As you can see, it's been on many people's minds for some time.

 

[Elmarc]

My understanding, based purely on the range of opinions expressed is that there is no understanding of what constitutes insufficient turbulence. Is what we call unidirectional agitation known to be a problem? Has there ever been anything resembling a scientific experiment on this? Does anyone know if rotation in one direction really results in insufficient turbulence. You'd need a transparent tank to see, wouldn't you? If the tank turning in one direction only "slices through the film" without creating any motion or only a uniform motion and therein lies the problem then when this ends and the tank reverses why does the film then experience any turbulence if there was none before? So is even a Jobo processor the right thing to use?

What is clear is that the OP's Rondinax/Lab box tank has a jerk built into to its motion so this would suggest that as a cause of his problem of what may or may not be bromide drag due to lack of developer motion this may be low on the list of likely suspects or so it seems to me

pentaxuser

It is actually possible to observe partly what happens re turbulence with the Rondinax just by removing the lid and simulating the development process. I may try that with a sacrificial roll just out of curiosity.
Your point about the jobo is interesting and I was thinking the same. Whichever direction the tank moves in, the flow pattern would be effectively the same, if I am visualising this correctly. Having said that, there are users who have switched over to this system to achieve more consistent results. So....