Bending that density curve: (dilution | development time | agitation)?

When developing roll film I rely on the combination of agitation intensity and development time to achieve the curve I want. But I cannot do this with sheet film, which is developed in a rotary processor and therefore the agitation is constant.

People often mention developer dilutions as yet another tool to control contrast. I have been playing with various Ilfotec HC dilution + development time combinations, e.g. high dilution + more time, or less dilution + less time. Honestly, I don't get the point. The results appear to be the same. Grain character changes a bit, but it doesn't matter to me in large format. I want to control the compensating effect. Is Rodinal the same way?

1. What is the point of these numerous HC dilutions then?
2. How do you control compensating effect under constant agitation?

Neither Rodinal nor HC/ HC-110 have meaningful compensation effects (nor were they designed to), despite the the fervent/fantastical wishes/ claims over the decades in print & online. Ilfosol 3 at 1+9 is intended to deliver meaningful development inhibition effects (real-world compensation effects), and things like XT-3/ Xtol are designed towards similar ends.

I've been using 510 Pyro to good effect. It's a staining/tanning somewhat compensating developer, but you need to use a higher pH fixer such as TF-4 or TF-5 (pH of 7 or higher).

The only way you get compensation effects is if the developer exhausts in the highlight areas. This is achieved by a number of schemes:

- Very high dilution dilution with infrequent agitation (semistand/EMA)
- Using a compensating developer like D-23
- Using two bath and water bath compensating development techniques

There is also a technique from David Kachel called "SLIMT" that prebleaches highlight with dilute potassium ferricyanide.

P.S. Just because you have a rotary processing system doesn't mean you have to continuously agitate. You can load the tank and agitate it infrequently manually.

Lachlan Young said:

Neither Rodinal nor HC/ HC-110 have meaningful compensation effects (nor were they designed to),

Click to expand...

That statement is true only if you limit yourself to manufacturer suggested dilutions and agitation schemes. Any number of people are getting compensation effect with highly dilute, minimally agitated Rodinol.

I have personally used HC-110 at 1:128 (well beyond Kodak's max Dilution F at 1:79), semistand processed the film and held north of 13-14 stops of printable SBR because of ... um, er ... highlight compensation effect.

Highlight compensation occurs when the developer noticeably exhausts in the highlights and the aforementioned techniques force this to happen.

So while it's true that these developers were not designed as compensating developers, claiming that cannot be made to do this at all is factually false.

That said, there are certainly better approach to compensation development/highlight management using D-23, Pyrocat-HD, two bath, and SLIMT.

Thank you everyone. Essentially my only lever here is choosing a developer which can deliver compensation effect under constant agitation.

To @chuckroast : you are right, technically I could agitate manually but filling up 2500-series tanks for intermittent agitation would be extremely inefficient in terms of chemistry volume per sheet.

I can’t answer your question about HC110, but I did do some experiments with high dilutions and continuous agitation rotary. I diluted the developer across multiple tank fills. So, I might fill and dump the tank 5 or 6 times, just during the development stage.
The tempering box is holding just the dilute developer for a single run in the white bottles.
I even experimented with a slowing water wash between the developer fills (black bottles).

chuckroast said:

That statement is true only if you limit yourself to manufacturer suggested dilutions and agitation schemes. Any number of people are getting compensation effect with highly dilute, minimally agitated Rodinol.

I have personally used HC-110 at 1:128 (well beyond Kodak's max Dilution F at 1:79), semistand processed the film and held north of 13-14 stops of printable SBR because of ... um, er ... highlight compensation effect.

Highlight compensation occurs when the developer noticeably exhausts in the highlights and the aforementioned techniques force this to happen.

So while it's true that these developers were not designed as compensating developers, claiming that cannot be made to do this at all is factually false.

That said, there are certainly better approach to compensation development/highlight management using D-23, Pyrocat-HD, two bath, and SLIMT.

Click to expand...

Except that it isn't compensation. What people claim to be 'compensation' is really just developing to lower contrast indices than meaningful compensation. This may nevertheless deliver the effect the end user wants, but it isn't compensation.
Real-world compensation effects will deliver a curve somewhere close to XP2 Super - i.e. a sharp toe, full shadow speed, but highlights that have a longer softer shoulder via development inhibition - if the highlights remain much more linear then it isn't really compensation at all, just a lower overall contrast index. All I'll add to this is that there is very good evidence in the industry/ academic photographic science literature that by the time DIR couplers were in use in C-41 film emulsions, getting similar effects in B&W was a key industry aim - and that they understood actual compensation effects far, far better than various garden-shed formulators have ever managed. Those outcomes were incorporated into developers and emulsion structures.

And yes, the major industry research labs investigated agitation to its end points too, to the point that there is excellent evidence in the industry standard texts that effectively show that if you are giving sufficient agitation for even development, you will have nil effects on sharpness, and any effects on contrast can be normalised via time compensation. If someone complains that they cannot 'expand' some particular emulsion today, it's not because of shortcomings of film or chemistry - in fact, it's quite the opposite - and largely because of development inhibition effects to improve sharpness relative to granularity, while simultaneously lessening the risks of the end user comprehensively frying their highlights and then complaining about it.

Lachlan,

I believe chuckroast was talking about true compensation; i.e., when, due to reduced agitation, the developer exhausts in the higher-density areas of the negative while continuing to work in the less-dense areas. Also, with very dilute developers, the development in the shadows can be nearly completely developed before the developer exhausts, leaving the higher-density areas underdeveloped (in relation to a "normal" development), which is also a compensating effect.

Did you misunderstand chuckroast, or are you saying that the above effects are not "true compensation" for some reason?

Adjusting developer time to control overall contrast gradient with a "normal" developer and recommended agitation is a very different thing.

Best,

Doremus

Doremus Scudder said:

Did you misunderstand chuckroast, or are you saying that the above effects are not "true compensation" for some reason?

Click to expand...

What I'm saying is that most of the popular assumptions about localised exhaustion and the specific causes are not very accurate at all, but that manufacturing R&D have found real ways of causing useful localised restraining effects & have widely incorporated them into products - however, some of those effects will restrict maximum attainable density with certain widely used developers when trying to reach higher densities ('Universal' developers will work around this).

Yeah, I've had a hard time with expansions with a number of film/developer combinations. Restraining effects built in by manufacturers explains this. Any hints on achieving expansions with "non-universal" developers? I used to get more contrast with dilute HC-110 and longer development times than I did with standard dilutions, where increasing development time just built fog density and not much extra contrast.

Best,

Doremus

Don Cardwell measured some curves for Rodinal:

Lachlan Young said:

Except that it isn't compensation. What people claim to be 'compensation' is really just developing to lower contrast indices than meaningful compensation. This may nevertheless deliver the effect the end user wants, but it isn't compensation.

Click to expand...

I don't have a densitometer than can correctly read through pyro stain so what I am about to say is entirely anecdotal and based on my observations across many film-developer combinations ...

When doing highly dilute very low agitation development, I see the highlights shouldered off so as not to blow out, full shadow speed, and increased contrast in the mid-tones. I do not see an overall reduction in CI.

The fact that the shadows stay in bounds but middle tone contrast is improved is exactly the opposite of what I'd expect with an across-the-board reduction in CI. In fact, one of the several reasons I went off to look into semistand and EMA was because the Zone System way of dealing with big SBRs is to contract development and increase exposure, thereby giving you exactly a lower overall CI. But this also compresses the mid-tones in ways I do not like.

Doremus Scudder said:

Lachlan,

I believe chuckroast was talking about true compensation; i.e., when, due to reduced agitation, the developer exhausts in the higher-density areas of the negative while continuing to work in the less-dense areas. Also, with very dilute developers, the development in the shadows can be nearly completely developed before the developer exhausts, leaving the higher-density areas underdeveloped (in relation to a "normal" development), which is also a compensating effect.

Did you misunderstand chuckroast, or are you saying that the above effects are not "true compensation" for some reason?

Adjusting developer time to control overall contrast gradient with a "normal" developer and recommended agitation is a very different thing.

Best,

Click to expand...

Yes, you have it right, I am claiming true compensation effects from semistand/EMA because of the aforementioned developer exhaustion in the highlight areas.

Try D-76 1+1.

@Lachlan Young what is the point of many different HC-110 dilutions then?

Axelwik said:

I've been using 510 Pyro to good effect. It's a staining/tanning somewhat compensating developer, but you need to use a higher pH fixer such as TF-4 or TF-5 (pH of 7 or higher).

Click to expand...

An alkaline fixer is unnecessary with 510 pyro. Pyrogallol and -catechol stain does not dissolve in acid fixer, in sulfite, etc.
510 pyro has the drawback that it's more prone to uneven development than e.g. pyrocat, and among the pyro developers, it's also one that's very prone to depositing excess overall stain that doesn't contribute to the image. This generally doesn't hurt in scanning or silver gelatin printing, but I found it to be significant problem with certain alt. process prints.
There are also recurring problems with people purchasing 510 pyro that suddenly dies or even arrives DOA from their supplier.
It's annoying to mix at home due to the slow dissolution of the ingredients in TEA and the high viscosity of TEA, so it effectively needs to be heated for the entire mixing time or it needs to sit for up to weeks or months for all the ingredients to fully dissolve.
Measuring out 510 pyro is also inconvenient due to the high viscosity and the unfortunately combination with small volumes needed; it's hard to consistently and accurately measure out e.g. 1ml of a very thick syrup. Care should also be taken to dissolve the 510 pyro properly when mixing the working strength developer as undissolved 'strands' of the syrup can cause grossly uneven development (not a theoretical argument; I've seen it happen).

510 pyro works, but it offers no benefit over other developers, and in fact, it turns out that anything 510 pyro has to offer, other developers do better.
You're right in that the tanning effect of pyro developers does result in some highlight compression, although with 510 pyro I suspect the compensation is mostly due to the developer basically dying during development. It's working life is very short indeed. This is also the cause for the high fog/general stain it produces.

Steven Lee said:

@Lachlan Young what is the point of many different HC-110 dilutions then?

Click to expand...

Things happen at the toe of the curve as well.
Why don't you ask @DREW WILEY - he's done a lot of fidgeting with HC110 to subtly twist film curves, also for mask-making.

Steven Lee said:

@Lachlan Young what is the point of many different HC-110 dilutions then?

Click to expand...

Subbing out for various dilutions of DK-60a and DK-50 that were used in graphic arts and other industrial purposes, with the ability to replenish in a similar manner to the DK developers.

koraks said:

Measuring out 510 pyro is also inconvenient due to the high viscosity and the unfortunately combination with small volumes needed; it's hard to consistently and accurately measure out e.g. 1ml of a very thick syrup. Care should also be taken to dissolve the 510 pyro properly when mixing the working strength developer as undissolved 'strands' of the syrup can cause grossly uneven development (not a theoretical argument; I've seen it happen).

Click to expand...

I'm not much impressed with 510 either, but I overcame the problem above by diluting the stock syrup in propylene glycol. I've no idea what - if anything - this does to the effectiveness of the developer but it sure makes it easier to measure. Obviously, you have use more of the diluted liquid to get the proper amount of stock in solution.

koraks said:

An alkaline fixer is unnecessary with 510 pyro. Pyrogallol and -catechol stain does not dissolve in acid fixer, in sulfite, etc.
510 pyro has the drawback that it's more prone to uneven development than e.g. pyrocat, and among the pyro developers, it's also one that's very prone to depositing excess overall stain that doesn't contribute to the image. This generally doesn't hurt in scanning or silver gelatin printing, but I found it to be significant problem with certain alt. process prints.
There are also recurring problems with people purchasing 510 pyro that suddenly dies or even arrives DOA from their supplier.
It's annoying to mix at home due to the slow dissolution of the ingredients in TEA and the high viscosity of TEA, so it effectively needs to be heated for the entire mixing time or it needs to sit for up to weeks or months for all the ingredients to fully dissolve.
Measuring out 510 pyro is also inconvenient due to the high viscosity and the unfortunately combination with small volumes needed; it's hard to consistently and accurately measure out e.g. 1ml of a very thick syrup. Care should also be taken to dissolve the 510 pyro properly when mixing the working strength developer as undissolved 'strands' of the syrup can cause grossly uneven development (not a theoretical argument; I've seen it happen).

510 pyro works, but it offers no benefit over other developers, and in fact, it turns out that anything 510 pyro has to offer, other developers do better.
You're right in that the tanning effect of pyro developers does result in some highlight compression, although with 510 pyro I suspect the compensation is mostly due to the developer basically dying during development. It's working life is very short indeed. This is also the cause for the high fog/general stain it produces.



Things happen at the toe of the curve as well.
Why don't you ask @DREW WILEY - he's done a lot of fidgeting with HC110 to subtly twist film curves, also for mask-making.

Click to expand...

I've never experienced any of those problems, and have used it with 35mm 120, and 4x5. In my experience it also dissolves in water better than HC110, and is easy-peasy to use. Haven't mixed my own yet, and since it lasts a long time I probably won't as long as Bostick & Sullivan is just up the road in Santa Fe. (And the brown negatives look cool!)

I use TF-5 and TF-4 fixers because neutral to alkaline fixers are recommended.

Perhaps you got a bad batch, didn't fully agitate, used an acid stop bath, didn't follow directions, or did something else wrong (maybe used a low pH fixer).

But what do I know... I've only had a year of college inorganic chemistry, passed the ACS exam, and taken several undergraduate and graduate geochmistry classes.

Lachlan Young said:

Subbing out for various dilutions of DK-60a and DK-50 that were used in graphic arts and other industrial purposes, with the ability to replenish in a similar manner to the DK developers.

Click to expand...

Yes, I think Kodak saw HC-110 as their universal replacement for nearly everything that preceded it, including D-76, particularly for volume machine processors.

HC-110 is a really versatile developer and I've used it many times conventionally (Dilution B) with a very large variety of film types and gotten great consistency of results. As I noted above, I also tried it super dilute (1+128) and got quite good semistand results with highlight compensation in a very long SBR environment.

The biggest problem with HC-110 has been availability as Kodak made themselves busy destroying their supply chains. I've not seen the latest version of this stuff but I am told it is not exactly the same and the newer stock is nowhere near as viscous.

chuckroast said:

I don't have a densitometer than can correctly read through pyro stain so what I am about to say is entirely anecdotal and based on my observations across many film-developer combinations ...

When doing highly dilute very low agitation development, I see the highlights shouldered off so as not to blow out, full shadow speed, and increased contrast in the mid-tones. I do not see an overall reduction in CI.

The fact that the shadows stay in bounds but middle tone contrast is improved is exactly the opposite of what I'd expect with an across-the-board reduction in CI. In fact, one of the several reasons I went off to look into semistand and EMA was because the Zone System way of dealing with big SBRs is to contract development and increase exposure, thereby giving you exactly a lower overall CI. But this also compresses the mid-tones in ways I do not like.

Click to expand...

Long story short, it isn't the stain. Highly dilute Metol produces inhibition via exhaustion effects, but that switches off when a source of semiquinone is added. Phenidone is capable of very intense inhibition effects, but that effect can be modulated from mild to strong via manipulation of the ratio of HQ (or other semiquinone source) - it so happens that a well known staining developer happens to fall within the range of the effects being produced (and maximal shadow speed) - and has a pH that will tend towards maximal sharpness (rule of thumb, carbonate buffer = more optimised for sharpness, borate buffer = fine grain - apart from Xtol/ XT-3 which seems to have set out to see if it could improve all 3 of sharpness/ granularity/ shadow speed). However, that is only part of the story - developer solvency causes the release of iodide placed in the emulsion for the specific purposes of development inhibition effects (e.g. Ilford Delta all but makes this explicit in the tech disclosures from when it emerged. Thus you can see that you will get more optimal results faster by combining the right P:Q balance, buffer choice and some degree of solvency, rather than only one part or another (as the non-solvent staining developers inherently will).

If your agitation is sufficient to not generate uneven development (and you can test for this - but the results may shock you, and clearly demonstrate why the film manufacturers make the recommendations that they do), you will not have meaningful impact on anything other than final contrast gradient. This has been very comprehensively studied by the film manufacturers (it had important relevance to litho film) - to a level and thoroughness (and controlled for evenness of development) that makes all of the minimal agitation claims of various would-be influencers absolutely laughable. That it works is more due to the material having been well enough engineered to withstand poor processing technique (some materials in the past had a known sensitivity to insufficient agitation).

chuckroast said:

Yes, I think Kodak saw HC-110 as their universal replacement for nearly everything that preceded it, including D-76, particularly for volume machine processors.

HC-110 is a really versatile developer and I've used it many times conventionally (Dilution B) with a very large variety of film types and gotten great consistency of results. As I noted above, I also tried it super dilute (1+128) and got quite good semistand results with highlight compensation in a very long SBR environment.

Click to expand...

Versatile, yes, but not a D-76 replacement. It was the same chemist (Henn) who was ultimately responsible for DK-20, D-23/D-25, Microdol/ Microdol-X and HC-110 (amongst others) - it's pretty clear that HC-110 was intended for where people were using DK-60a and DK-50 in large scale applications, not D-76 - especially in places like the graphic arts industry, where all the HC-110 dilutions could end up getting used in carrying out various day-in-day-out operations that were vital to the production of widely read popular media. That HC-110 became a cult touchstone for a particular kind of workshop-oriented B&W fine-art-manque photographer owes more to the photographic media/ workshop influencers of the 60s/70s/80s that were the gatekeepers of that world.

Lachlan Young said:

Long story short, it isn't the stain. Highly dilute Metol produces inhibition via exhaustion effects, but that switches off when a source of semiquinone is added. Phenidone is capable of very intense inhibition effects, but that effect can be modulated from mild to strong via manipulation of the ratio of HQ (or other semiquinone source) - it so happens that a well known staining developer happens to fall within the range of the effects being produced (and maximal shadow speed) - and has a pH that will tend towards maximal sharpness (rule of thumb, carbonate buffer = more optimised for sharpness, borate buffer = fine grain - apart from Xtol/ XT-3 which seems to have set out to see if it could improve all 3 of sharpness/ granularity/ shadow speed). However, that is only part of the story - developer solvency causes the release of iodide placed in the emulsion for the specific purposes of development inhibition effects (e.g. Ilford Delta all but makes this explicit in the tech disclosures from when it emerged. Thus you can see that you will get more optimal results faster by combining the right P:Q balance, buffer choice and some degree of solvency, rather than only one part or another (as the non-solvent staining developers inherently will).

Click to expand...

This may be taken as a summary of chemical reactions, expounded over 2 chapters in Photographic Processing Chemistry by LFA Mason, but does not appear to include the effects of diffusion, p114 therein,1975 edition, and it is surely diffusion or lack of it that causes the bending of the curve in highlights with reduced agitation for dilution of a given developer?

eg, Film Developing Cookbook 2020 p41 ".....Adams emphasizes the reduced highlight contrast with HC-110 at 1:90 from concentrate."
FDC p 41-42 "Even in a full strength developer like D-76 or Xtol, when agitation is minimal, there will be moderate contraction due to suppressed highlight development."

Alan Johnson said:

This may be taken as a summary of chemical reactions, expounded over 2 chapters in Photographic Processing Chemistry by LFA Mason, but does not appear to include the effects of diffusion, p114 therein,1975 edition, and it is surely diffusion or lack of it that causes the bending of the curve in highlights with reduced agitation for dilution of a given developer?

eg, Film Developing Cookbook 2020 p41 ".....Adams emphasizes the reduced highlight contrast with HC-110 at 1:90 from concentrate."
FDC p 41-42 "Even in a full strength developer like D-76 or Xtol, when agitation is minimal, there will be moderate contraction due to suppressed highlight development."

Click to expand...

The general implication seems to be that diffusion rate has an impact on rate of development, but not exhaustion or inhibition effects (which are much more micro in scale) - i.e. you might get certain effects with D-23 and a waterbath in an overly thick, relatively buried iodide emulsion, where the rate of developer diffusion out of the emulsion is sufficiently slow that the water bath dilutes the D-23 to the point that it causes exhaustion effects occur - whereas with something like Tmax 100 (where the supercoat had to be made thicker to slow the rate of diffusion to prevent overly fast development rates - see Shanebrook), something that is implicitly designed to cause inhibition effects will do the job better, more controllably and predictably. Any fairly solvent developer will start to cause inhibition effects beyond a certain development time owing to release of iodide & bromide (and other components) from the action of the developer on the emulsion. Ilford exploit this with the core-shell Delta structure - you can see the effect very clearly if you compare Delta 3200 in ID-11 vis-a-vis Rodinal, neither of which have developing agents set up to produce inhibition effects, but one of which has a high enough level of solvency to interact strongly with the emulsions. When Ilford stated that some of the upgrades they did to Delta were to 'broaden the range of suitable developers', it was effectively to do with making these effects less dependent on higher levels of developer solvency - Delta 400 is really remarkably similar across a lot of developers as a result.

The other problem with some of the earlier research on diffusion was that it was apparently done on dry, not wet emulsions... And that while extremely thickened developers (e.g. Polaroid monobath thick) can cause some useful effects, normal thickness developers don't seem to offer better or worse results in real-world use (outside of very specialist aerial/ recon applications - and even those seem to have changed - likely because it was easier to make an emulsion that did the job with a regular film developer, rather than making a far messier and complicated developer). If you wanted to waste your competitiors' R&D time you'd disclose something that while not totally inaccurate, wasn't as effective as the simpler yet better mechanisms that have might have been found en-route to formulating ID-68 etc...