Warmtone and cooltone paper developer

I am asking myself what makes the chemical difference between warmtone and cooltone paper developer. There are some paper developers on the market in two variants, but what makes the difference?

Does anyone know?

This is a very common question that requires a long answer... so please search the past postings as well as old pure-silver archive.

The color of the image is primarily determined by the size, shape and surface structure of the developed silver. There are numerous techniques to modulate these factors in emulsion making as well as developer formulation, but most of the knowledge is empirical. Many information printed on amateur darkroom books are also cut and paste work from old books, sometimes out of context.

Warmtone developers are usually made from hydroquinone only, with significant amount of bromide, and pH sufficiently high to develop in 3-10 minutes. These developers require overexposure of the paper and premature termination of development, so it is not easy to make many prints to exact same image density. However, if you want warmtone without toning, this is absolutely the bst way.

"Warmtone" developers containing Metol, glycin, p-aminophenol, Phenidone, Dimezone, etc. are not quite warm tone developer, but they can be formulated to produce warmer side of neutral black, when combined with right paper. The effect is usually much less dramatic than the true warmtone developer. Development is also short, 1-4 minutes range.

Neither type of the developers has warming effect if used with neutral or cold tone paper. They must be used with warmtone paper to be fully effective.

No matter which developer formula you use, if you want good warmtone, it is best to give slight overexposure to the paper and terminate development when you see the right image density. This requires some practice, but this is sort of a required sill to make most beautiful warmtone without toning. It is also useful to use very slow developer, restrained with plenty of bromide.

Coldtone developers usually contain organic compounds that have high affinity to silver halide. A very common agent is benzotriazole, 5-methylbenzotriazole, 5-nitrobenzimidazole, 5-nitroindazole, 1-phenyl-5-mercaptotetrazole (more commonly added to emulsion), 2-mercatoimidazole 6-sulfonic acid and other proprietary compounds. These agents generally retard development, and can't be added too much. Also, many of these compounds are "taken up" by emulsion at a rate considerably different from the rate of taking up the developing agents and water, so that the color of the image may not remain stable over the life of the developer. There are a lot of proprietary compounds to overcome these problems and provide good blue black image, but I doubt that only technologically advanced manufacturers can use such compounds.

HOWEVER, if you want to make warmtone image with polysulfide or selenium toning, it is best to use a warmtone paper and develop it in neutral tone developer rather than special purpose warmtone developer. Many warmtone developers produce prints that become very cold toned, or lose richness of the blac, when toned in these toners. Making warmtone image without toning, and making warmtone image with toning require different kinds of developer formulation. This point was very clearly described by people like Ira Current when he was active in photography, but more recent authors seem to be ignorant of his work or common practice of 1940-1960s.

Hans, a far shorter answer is warm-toned developers typically contain higher levels of bromide, and no organic restrainers.

They can be MQ or PQ bases, although other formulae may use chloroquinone or other developing agents.

The excellent warm tone Agfa Neutol WA is a PQ developer, and if you want to make up your own developer from raw chemicals Ilford ID-78 gives very similar results.

Ian

Ryuji and Ian,

thanks for your reply. It seems you have some detailed chemical knowledge there. I am looking from a very specific perspective (reversal processing) that is not too different from paper development in the end.

I have found that the image tone of the film depends on the film and the developer. Both together seem to build the image tone. With the same developer some films end up cold others quite warm. The same film in different developers also ranges from cold to warm.

From your summary it appears to me that the addition of an organic compound can render the image tone colder? Is there a single low hazard substance that could be added to an existing developer to adjust the image tone? That would be nice.

I am already adding stannous chloride to the developer as a fogging agent, I wonder whether that has a known effect on image tone.

Hans

Hans, you could look at warm toned developers originally formulated for lantern slides and use one for your second developer.

Potassium Bromide is usually increased to improve the warmth of developers, but adding more requires a print to need increased exposure

I'm not sure whether the Stannous Chloride has any effect on image colour, I'd prefer to use light reversal and its easy.

You might also look at using the Ilford published formulae IT-8 to tone your slides after processing, or perhaps just use the very simple developer part of the fomulae for your 2nd development.

Another thought is use Sandy King's excellent Pyrocat HD for the 2nd development.

Ian

I am not so interested in warm tone options as Rodinal already delivers neutral to warm tone slides. I am seeking alternatives that allow cool neutral results, possibly with image tone adjustment by quantitiy of dosage.

I do no longer consider light reversal as an option. Chemical reversal is much more controllable. Toning affects Dmin in the slides, also not desirable.

It seems that adding a coldtone agent would not go together with the fogging agent? Benzotriazole is quoted as a fogging restrainer to remove fog from aged film (or paper). The stannous chloride in my second developer aims for the opposite. From my understanding this is a conflict. Or may these compounds still be combined in a single bath?

Ian Grant said:

You might also look at using the Ilford published formulae IT-8 to ... use the very simple developer part of the fomulae for your 2nd development.

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Interesting. To you have a link available? Google can't find it.

The IT-8 formulae should be in the article section, but Sean hasn't yet reposted the toners, the section is still awaiting its update. I'll PM you the formulae.

OK you want to cool the developer tones then add Benzatriazole solution, it shouldn't conflict with the stannous chloride. Just like increasing the bromide level it increases the contrast.

Ian

Hans Borjes said:

I have found that the image tone of the film depends on the film and the developer. Both together seem to build the image tone. With the same developer some films end up cold others quite warm. The same film in different developers also ranges from cold to warm.

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Yes, among the modern emulsions, slow tabular grain films like TMX or Acros is more prone to produce warmer tone, while APX400, TMZ, Delta 3200 and other coarse grained films are likely to be neutral toned.

From your summary it appears to me that the addition of an organic compound can render the image tone colder? Is there a single low hazard substance that could be added to an existing developer to adjust the image tone? That would be nice.

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6-nitrobenzimidazole would be best, but benzotriazole is more commonly available and cheap.

I am already adding stannous chloride to the developer as a fogging agent, I wonder whether that has a known effect on image tone.

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If you prefer neutral tone, I think fogging by stannous chloride may help you.

Ian Grant said:

Hans, you could look at warm toned developers originally formulated for lantern slides and use one for your second developer.

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The emulsions used for lantern slides were very different from modern film emulsion. They are more similar to graded warmtone paper emulsions. So information on lantern slide developers don't really apply without modification and necessary trial and error, of course. But I have good summary of developers commonly used for warmtone images on lantern slides. They are more similar to AGFA 120.

However, Hans needs cold tone anyway, which is actually quite a bit easier task.

Many warmtone developes are also glycin based. The same principles apply. With modern papers, the paper seems to make a very big difference. A coldtone paper will usually still be coldtone (or at least neutral) in most warmtone developers, and a warmtone paper may be limited in the degree of warmth that you can develop.

This may all be easier than I expected. Benzotriazole seems to be worth investigating.

Which starting point concentration do you recommend for a moderate change in image tone?

My current ingredients for one film single shot are

Water 230ml
Stannous Chloride 50mg
Agfa Rodinal 30ml

How much Benzotriazole powder would change the image tone but not retard development?

Well, that's a bit tricky question since you used a proprietary developer. My wild guess would be 0.2g/L and see if it retards too much or doesn't have much effect. Then double or halve and repeat . Is there a reason why you don't use D-72 or D-19 type developer for the second developer? I know they make coarse grained final image (while they are better for the first developer where grain sizes don't matter) but they can be made cold tone fairly easily.

Ryuji said:

My wild guess would be 0.2g/L and see if it retards too much or doesn't have much effect. Then double or halve and repeat .

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Thanks. That's helpful.

Ryuji said:

Is there a reason why you don't use D-72 or D-19 type developer for the second developer? I know they make coarse grained final image (while they are better for the first developer where grain sizes don't matter) but they can be made cold tone fairly easily.

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I have not stumbled over D-72 or D-19 so far. When different developer options have been assessed key criteria were keeping property and long term availability. All other alternatives I found are much more limited in keeping than Rodinal. Requirement was and still is sporadic low volume processing.

I am not running a commercial lab ;-)

Typically benzotriazole is used as a 1% solution, and an average is between 2.5 and 5 ml per litre of working solution

Part of your problem may well be using Rodinal, all the formulae I've seen and tried used fairly vigorous developers for first and second development. My normally processed B&W negatives processed in Rodinal have a more delicate and warmer colour compared to the same films processed in D76, Xtol, Ilfotec etc.

Developers like PQ Universal, or Suprol are typically used at 1+4 for reversal as opposed to the more usual 1+9 for papers. May & Baker (now Champion) used to produce as superb technical sheet on reversal processing with Suprol.

Ian

Ian Grant said:

Typically benzotriazole is used as a 1% solution, and an average is between 2.5 and 5 ml per litre of working solution

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That would be 0.025 to 0.05g/L if I calculated correctly, which is is roughly in the same order of magnitude as quoted by Ryuji. Because of curiosity I have ordered some Benzotriazole today.

Ian Grant said:

Part of your problem may well be using Rodinal, all the formulae I've seen and tried used fairly vigorous developers for first and second development. My normally processed B&W negatives processed in Rodinal have a more delicate and warmer colour compared to the same films processed in D76, Xtol, Ilfotec etc.

Developers like PQ Universal, or Suprol are typically used at 1+4 for reversal as opposed to the more usual 1+9 for papers.

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I am using Rodinal in fairly strong dosage. But it seems you are right that Rodinal builds a warm tone result. Also for curiosity I bought some Eukobrom today and ran a test roll of FP4 with Rodinal in the first developer and Eukobrom in the second developer. Previous tests have shown that Eukobrom already damages the emulsion partially if used in the first and second developer. This does not happen if Eukobrom is used in the second developer only. The image tone has changed from warm towards neutral and Dmin is better than before. Grain is smaller, but this is no surprise.

It seems I have to repeat this experiment with HP5 and Pan F to see what happens there.

Ian Grant said:

OK you want to cool the developer tones then add Benzatriazole solution, it shouldn't conflict with the stannous chloride.

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Hmm. It may not conflict in chemical sense, but it conflicts from technical/functional point of view. I added 50mg to the first and 50mg to the second developer. Somewhat difficult to dissolve this stuff, but 5 minutes later...

Benzotriazole in the second developer did what I was afraid it would do: it restrains the fogging of the stannous chloride and leads to uneven development.

I also repeated an experiment that was done once ago with 135 film on 120 film: replaced Rodinal by Tetenal Eukobrom. Because I was aware of emulsion 'damaging' of FP4 I added a hardening acetic acid bath after first development and proceeded to bleach without additional washing. The carry-over from hardening to bleach impacted the bleach result so that part of the images remained negative. Clearly a defect but it can be seen that way that the white spots on the posive are black spots in the negative. I see this as evidence that in the case of Eukobrom the white spots are not created during bleach (which I expected) but during first development. Possibly Eukobrom and KSCN develop more actively in 'bubble' areas?

What other options exist apart from trying different film emulsions? I have no idea about the image tone of Neofin blau versus Rodinal. Somebody has negatives for reference?

You could use stannous chloride bath first, and then developer with benzotriazole.

Alternatively, since your goal is to fog the emulsion, you could use a very dilute solution of thiourea or sodium sulfide, with or without stannous chloride, as the fogging bath. They should be in alkaline condition, e.g., with carbonate or hydroxide. The solution doesn't need to be strong enough to see any "toning" effect. They will create invisibly small but big enough silver sulfide specks on grains to render them developable. Thiourea is not smelly and is more preferable if it works just as well as sulfide. Or you could use light to fog the film. All of these would increase the number of steps though, and you might not be excited with that.

There are other potential ways but they require organic compounds that are less accessible than anything that got mentioned above.

Most recently I have discovered that the original Scala chemistry can be ordered from A&O website. Not that I intend to - the amount of stock solution is far too big for home use.

But there are also safety data sheets that tell some details about ingredients of the chemicals:
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Interesting are contents in the second developer:

• Sodium carbonate
• 2,2'-Oxydiethanol
• Metol

According to this website http://www.jackspcs.com/pitone.htm, sodium carbonate can be used to cool the image tone and metol can be used to reduce contrast. I wonder whether this is the intention to have these components in the Scala second developer.

I also wonder whether sodium carbonate can simply be added to another developer to cool image tone and what side effects can be expected.

Hans Borjes said:

According to this website http://www.jackspcs.com/pitone.htm, sodium carbonate can be used to cool the image tone and metol can be used to reduce contrast. I wonder whether this is the intention to have these components in the Scala second developer.

I also wonder whether sodium carbonate can simply be added to another developer to cool image tone and what side effects can be expected.

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Don't believe those stuff. Sodium carbonate itself is used in both warmtone and coldtone developers. Carbonate has no influence on the image tone other than that via the change in pH.

Ryuji said:

Don't believe those stuff. Sodium carbonate itself is used in both warmtone and coldtone developers. Carbonate has no influence on the image tone other than that via the change in pH.

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Thanks for the clarification. I almost attempted a test.

By the way, if you are into manipulation of image tone, I will have an article up on this topic soon. I had this up on my old server, but I took it down when I changed the system a few years back and never republished it (among several other articles). Now my wiki system is on a new server and I'm in a process of putting some old stuff back, and one of them is an article about image tone (hue). It's technical but since you're so enthusiastic about it you might find something in it. To find it, go to my photo chemical site and search for image hue, maybe later this week.