Donald Quall's Paracetamol "Rodinal" works! :D

Donald Qualls said:

Hydroquinone is a developing agent that, in the absence of other agents and in suitable conditions of preservation and pH, is accelerated by its oxidation products; its analog ascorbate or erythorbate (more correctly, L-ascorbate that functions as a vitamin and D-ascorbate that doesn't) seems likely to give similar results, though it might require slightly different solution conditions to work best.

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Correct about hydroquinone.

Ascorbate is not an analog of hydroquinone. They are totally unrelated compounds. Ascorbate alone has no lith development property and it is never used as a lith developer, for research or for practical applications. Oxidation products of ascorbate have very different properties from those of hydroquinone. (Exception is ones that contain hydrazine derivatives. But then infectious development is due to hydrazine.)

Erythorbate is not D-ascorbate. Ascorbate has two chiral centers, there are 4 total of stereoisomers: L-ascorbate, D-ascorbate, D-arabo-ascorbate (erythorate), and L-arabo-ascorbate.

I should not have let myself get defensive. I don't want to be offensive either. Quarrelsome, maybe. Ryuji, your answer was hardly a description of how to tell if the films and developers we normally use are subject to or capable of infectious development. How can an emulsion we make ourselves give us that information?

What do you make of the following statement, found on p. 284 of the third edition of "The Theory of the Photographic Process", speaking of development by hydroquinone:
"When the sulfite concentration is less than 1%, the semiquinone can influence neighboring grains."

Does that not seem to indicate that my sulfite-free solution of hydroquinone, NaOH and KBr would be capable of infectious development?

The rest of this is a funny story.

I had experience with the results of true infectious development in my early days with NACA, beginning in 1952. Records of strain gage time-histories and other flight test variables were recorded on film in oscillographs. These were often reproduced verbatim by lithographic film for publication. That is, they SHOULD have been verbatim. Upon one occasion, the proofs showed a time history that had a backward loop. The original line had dropped out due, I'm sure, to a weakness in the original trace aided by infectious development, and a photo lab technician had etched it in artistically with his knife. From that time on, such corrections had to be made by
the research engineers with reference to the original. There were also pinholes, so we learned the use of the etching knife and opaqueing fluid.

gainer said:

Ryuji, your answer was hardly a description of how to tell if the films and developers we normally use are subject to or capable of infectious development. How can an emulsion we make ourselves give us that information?

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I don't know about your emulsions but my emulsions can be used to test for infectious development. For that matter, you can test with a fresh bottle of Liquid Light, using the same technique I described above. But you can get more precise data obtained at Kodak Labs in literature.

What do you make of the following statement, found on p. 284 of the third edition of "The Theory of the Photographic Process", speaking of development by hydroquinone:
"When the sulfite concentration is less than 1%, the semiquinone can influence neighboring grains."

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You get what you read. That does not mean infectious development in narrow sense.

Does that not seem to indicate that my sulfite-free solution of hydroquinone, NaOH and KBr would be capable of infectious development?

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Read one of my earlier responses here. I already described the difference.

Ryuji said:

You get what you read. That does not mean infectious development in narrow sense.


Read one of my earlier responses here. I already described the difference.

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So the effect on unexposed portions of emulsion adjacent to exposed portions that causes development of the exposed portions to cause density to develop in the unexposed portions is not infectious development in the narrow sense. Tell me again what is the virtue of the narrow sense. How is that "playing what is not there"?

My previous reference to it:

Ryuji said:

Generally, infectious development means a process in which unexposed grains are developed in the vicinity of heavily exposed grains. This is the case with modern lith films and lith developers containing hydrazine and/or tetrazolium derivatives. However, in classic hydroquinone-only lith developers, this does not happen to any significant degree. What happens is a process in which lightly exposedgrains are developed in the vicinity of heavily exposed grains, where the same lightly exposed grains would not be developed otherwise. Many photographic scientists and engineers who work in the field of high contrast films/developers reserve the term "infectious development" for hydrazine/tetrazolium type system, not for classic hydroquinone-only lith system.

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Sure, but the agent is thought to be of the semiquinone type. In the absence of sulfite, the semiquinone causes similar appearing symptoms without the hydrazine. Sulfite decreases the effect with or without the hydrazine. I doubt that we will see completely unexposed grains in the film we get over the counter. When I see narrowing of lines in the negative of a printed circuit, I think infection. Nowadays, I print my PC 's on my ink jet and use direct positive resist, so don't see the effect. In fact, I don't remember how the subject came up here. Maybe that's an advantage of being 78.96 years old. I certainly wish there were some others.

gainer said:

In fact, I don't remember how the subject came up here.

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Lith development? IIRC, some body mentioned making a
lith developer of ascorbic acid.

As nobody has gone beyond Dr. Gudzinowicz's
explanation, my understanding of the phenomena is
restricted to the dozen or so times I've read his
short treatise.

As I understand it semiquinone build up occurs as
hydroquinone is oxidized upon it's reduction of silver.
Semiquinone is a more potent reducing agent. At very
low sulfite levels, the Dr. mentions 0.2%, the much
unhindered semiquinone reduces silver and itself
is oxidized to quinone. A hydroquinone + a
quinone = 2 semiquinones. And so the
population of the semiquinone
increases exponentially.

At a 2% sulfite concentration formation of the quinone
is effectively blocked. Some interesting in between I'd
say; 0.2% to 2.0%. Of course some semiquinone is
produced because development of a more normal
type does occur. At least three variables I see
are, ph, the absolute concentration of sulfite
and, it's ratio with hydroquinone. Dan

gainer said:

Sulfite decreases the effect with or without the hydrazine.

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That's incorrect. Hydrazine can cause infectious development in sulfite-rich developers similar to PQ or phenidone-ascorbate type rapid access developers. Otherwise, photographic industry would not consider it to be an improvement over classic hydroquinone-only lith developer. Tetrazolium compounds and quarternary amine boosters also work very well in sulfite-rich developers.

Again, before you assert something, I recommend to check known facts.

I doubt that we will see completely unexposed grains in the film we get over the counter.

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Why do you want to forever argue about something that's been shown by several scientists and also something I can show in my lab?

It was not my assertion. It was a rewording of the assertion of Stauffer, Smith and Travelli that I found in my readings on p. 367 of The Theory of the Photographic Process. It deals with the fogging effect of adding hydrazine to a developer that has one or more hydroxyl groups, which causes several grains to develop for each exposed grain. I quote: "Since the fogging effect is dependent on the presence of normally developed grains, and is decreased by sulfite which reacts with the oxidation products of the developer, Stauffer, Smith and Travelli concluded that the fogging agent is formed by interaction of oxidized developer and hydrazine, and that the agent is probably of the semiquinone type. The effect has been termed infectious development."

Follow your own rules.

In reality, practical modern lith developers don't use bare hydrazine. An example of useful forms is N-acylhydrazine derivatives. Most useful ones are proprietary, but you can learn about how they are designed in US Patents 4269929 (Nothnagle, abotu old Kodak hybrid system) and 5688630 (Yamada et al., about Fujifilm Integra systems from 1990s). And these agents are used with tetrazolium compounds and amine compounds, including pyridinium salts, in high sulfite developers to maintain good shelf and working life while keeping extremely high contrast. Relatively recent high contrast films also contain some of these compounds in the emulsion.

These modern systems are results of more sophisticated organic synthesis and these compounds are very well designed, compared to those four compounds tested by Stauffer, Smith and Trivelli in Kodak Research Laboratories Communication No. 974. (You misspelled Trivelli.)

Also, Stauffer et al., only had a couple of brief statements about the effect of sulfite. The mechanism is now known, but the hydrazine compounds are so designed to lead the desired reaction faster than the undesirable sulfonation reaction with sulfite, so in reality, those Fuji and Kodak systems use a liberal amount of sulfite, as you see in the examples of the patents. You'll find more details of the reactions and the designs of the hydrazine compounds in a paper by Yamada, Kawato, Hirano and Katoh (1999) The development of new nucleating agents for the low-pH graphic arts system, J. Imaging Sci. Tech., 43, 103-110.

However, none of this is going to change the fact that ascorbate-alone developer is not capable of lith development, and the fact that hydroquinone-only classic lith developers do not involve "infectious development" in modern, or narrow sense. These two are the points around which you started an argument, and I have no desire to continue. If you continue to argue about these things, I request a good reason.

I agreed a long time ago that you were probably right about the ascorbic acid. It was only your suggestion that I was going off half cocked about nearly everything I write that egged me on. When did you start reading about photographic technology?

Argument is always useful when carried on in polite fashion. We learn things that might no come to light otherwise. It was long considered a fact that garlic would destroy the power of a permanent magnet. It was long considered a fact that tomatos were deadly poison. Nobody wanted to do the experiments to prove one side or the other. Permanent magnets were precious. Life also.

Peace.

What sometimes irritates me is that a lot of arguments I see (not just on this thread) are about something that's already discussed, experimented and its results published. If someone needs to know the upshot answer without going to a decent research library, it's fine to post a question, but I don't understand why people start an argment about something they don't really know but for which the answer already exists, especially if the person gets unhappy when s/he is reminded that the argument is wrong. I see no point of having a new argument about done deals.