catechol meets Rodinal

[gainer]

While we're at it, don't forget p-aminophenol with hydroquinone, both very soluble in glycol or TEA. We should have a glycol-soluble sulfite ion carrier to go along with them. That is one advantage of the synergism between ascorbic acid and the aminophenols. It needs no sulfite to enable that synergism.

 

[Ryuji]

Catechol and glycin show a lot of promise, but there are solubility issues with glycin and glycol, and I'd rather avoid aqueous solutions if possible.

I don't know what your goal is in doing this, but I'd rather set the goal in photographic terms, then select suitable developing agents, etc. Solvent system would be the last concern. Plus, there is nothing wrong with water.

Enter p-aminophenol, the agent best known as the reductant in Rodinal. Users of Rodinal know that developer produces virtually no aerial fog, which is what initially attracted my attention, but thanks to Pat Gainer, I've also learned that the base is soluble in glycol.

When did you see aerial fog with any developing agent? In reasonably well formulated developers, aerial fog shouldn't happen.

 

[Ryuji]

But does the presence of stain always indicate tanning? Several important sources state that hydroquinone does not tan well.

If you are referring to the aerial fog issue, aerial fog is silver stain. It is caused by some active oxygen specie, probably hydroxyl radical (denoted OH*, OH., .OH, etc.), which is generated when developing solution is in contact with air, especially in presence of cupper, iron or manganese. This is a potent oxidizing agent that takes different reaction pathway. The OH* can fog unexposed, undeveloped silver halide crystal to render it developable in the developer.

As you see, this is most common with developers with low or no sulfite, bromide and other antifoggants. Also, the risk of aerial fog is related to the reactivity of the developing agent and the metal catalyst. Inactivating the catalyst activity, preferrably in addition to use of sufficient sulfite, is the cleanest way to solve the problem. It is also effective to incorporate suitable free radical scavenging agent(s), especially in case of ascorbate developers.

In some cases, where oxidized form of developing agent is more potent, such as hydroquinone, catechol, pyrogallol, etc., these agents can be oxidized by air and then the oxidized form of the developing agent can fog the grain, as in the classic lith developer. But this type of reaction generally requires chlorobromide emulsion (with less bromide) or some special additives coated in the film. So this remains a small possibility but not a practically viable cause of aerial fog in film processing.

 

[gainer]

Well, I think the best way to turn iron into gold is to make fantastically good iron-based prints and sell them for gold.

Ryuji, I think the major premise of all this is to have fun while we pretend to be serious. Or is it the other way round? I'm too old to keep track of such things.

When the purpose is to produce a developer that gives a negative that blocks UV, some do strange things. When the purpose is to produce a developer that can sit on a shelf, be forgotten, resurrected and used by our descendents, others do even stranger things like looking for solvents that do not allow ionization until water is aded even if you leave the lid off. Sometimes when we look for frivolous things, we find figurative gold. Other times, we find the brown, gooey, smelly stuff.

 

[Ryuji]

Ryuji, I think the major premise of all this is to have fun while we pretend to be serious. Or is it the other way round? I'm too old to keep track of such things.

I don't find that fun at all, especially when compared to all other kinds of fun in life (or photography).

 

[avandesande]

Non aqueous solutions last much longer than aqueous solution. You might be able to make a slightly 'better' developer with water, but what good does that do you when the developer immediatly starts to degrade?

I don't know what your goal is in doing this, but I'd rather set the goal in photographic terms, then select suitable developing agents, etc. Solvent system would be the last concern. Plus, there is nothing wrong with water.

 

[Dinesh]

Thanks Jay, I appreciate all your efforts!

 

[Ryuji]

Non aqueous solutions last much longer than aqueous solution. You might be able to make a slightly 'better' developer with water, but what good does that do you when the developer immediatly starts to degrade?

My water-based ascorbate developers can last for months in sealed containers. If I allow them to come in contact with air for many weeks, the solution discolors. One print developer can last for many hours (at least 24) in an open tray without changing its photographic property.

So, I think nonaquaous stock is unnecessary, especially if it's used as a justification to leave out any means of stabilizing the developing agents. Developers like that can be unreliable during use.

 

[gainer]

Perhaps it can theoretically be unreliable in use, but I have not had any such experience, nor have I had any reports of such experience. Besides, you can add anything to the working solution that moves your spirit if you think it will help. I think you will find that the all-organic stock solutions will last for years, even with the lid off.

 

[Ryuji]

I'm not making my developers to keep for years with the lid off. I'm making them to use them to make images of good quality. As such, I find it unacceptable to do your "add this now" and "add this later" approach. The meal has to be ready to eat, and it must be good.

 

[Ryuji]

Ryuji,

finding fault in theory is only of use in theory, and has very little practical value for working photographers. If these developers are faulty in some way, it should be very simple for a person of your expertise to show data that supports your objections, and illustrates the shortcomings of these developers compared to your own. Short of that, I am not interested in your theoretical biases. Your disregard for Pat Gainer's work is well documented, and need not be restated here.

Jay

Jay, you are switching the matter of facts with matter of belief and dogma.

I'm making practical developers and making images using them. Theory? I use them as a tool when I make my chemicals and emulsions, as well as a tool to verify and understand how they operate. Actual use of my chemicals is completely separate from theoretical understanding. The latter is transparent from the user's viewpoint.

Comments such as yours are often made by those who take amateurish approach who don't understand the theory, nor know how to use it. I don't regard too highly of dogmatic statements, empty claims, and arguments made in the line of "theory is irrelevant" especially when those people are making suggestions devoid of chemical insight and deep understanding.

I don't wish to repeat your argument with Sandy, so I won't go far. But I would like to suggest that you don't attack or reject chemistry, unless you fully understand it.

 

[avandesande]

We aren't talking about ascorbate developers here, are we. Rodinal is in water too and can last for decades.

You seem to like to argue for the sake of argument and contribute little.

My water-based ascorbate developers can last for months in sealed containers. If I allow them to come in contact with air for many weeks, the solution discolors. One print developer can last for many hours (at least 24) in an open tray without changing its photographic property.

 

[Ryuji]

I have tested MANY variations of ascorbate developers since 1990s, including Gainer formulae when they were published in magazines years ago. But to remind you ascorbate develoeprs are known since 1930s and people like T. H. James used them in 1970s. The problems in keeping property, for example, is well known among researchers since then. Regarding the buffering property of triethanolamine, I discussed it at various places, but to summerize it here, TEA is a very poor buffering agent outside the range of 7.4 to 8.2. The developer Gainer mentioned above uses the pH far above this range. I even mentioned a suitable buffering agent for his target pH in the past, where Gainer was on the thread, either here or on Photo.net, but he has not adapted it.

I don't see value in publishing what's already known, just because I duplicated it in my hand. I find it more valuable to spare people's attention to something new, or something that contradicts what's already known (or believed).

 

[jim appleyard]

Getting back to the topic, I await your findings Jay. I've never thought about this combo, catechol and Rodinal, before.

 

[gainer]

It would be nice if I could be left out of this discussion. Certainly the properties of ascorbic acid and its relatives have been known for a long time. So have those of all the chemicals Ryuji uses. That is beside the point. I have not, in fact, promoted any of my formulas above any other. With regard to TEA and glycols, all I did was to point out that they could be used as solvents and some ways to do that, and some results of a simple test of aerial oxidation. Others have run with the ball, as the saying goes.

Is it a fact or a theory that buffer capacity is a "GOOD THING"? There are many in the literature that seem to depend upon poor buffer capacity for their touted qualities. I am not sure we can treat the TEA separately when it is used as both solvent and alkali. The ascorbic acid has to form a compound with whatever alkali is available. At least there must be enough OH to make it H'less in effect. There is in fact no inorganic compound in PC-TEA. No sodium to form that ascorbate. You can make a PQ-TEA with no sodium phenolate (or equivalent salt) in it. I am not capable of doing a theoretical analysis of whatever you would call the TEA analog of ammonium ascorbate or ammonium phenolate for buffer capacity. All I can say is that whatever problems that might cause, it didn't.

 

[Ryuji]

Jay, one problem with wrong buffering agent is inconsistent developer activity across batches. Because the solution pH is not buffered, the solution pH is very sensitive to small measurement errors when mixing each batch. The same inconsistency problem occurs when the developer is aged. It's very well known from early 20th century. Because of this, D-76 formula, for example was compared against several of buffered versions. Of course, a buffered version is superior in consistency, so that's what's used today.

Developers for practical fine-art and commercial uses should be made with robustness as a design spec, whenever possible. Ad-hoc approach may produce acceptable result sometimes, and that may be good enough for casual chemistry experiments for non-serious applications, but it is the consistency and reliability that matters a lot in production use.

A big part of the problem can be instantly removed by replacing the buffer with the correct agent. Why you insist in not using the right agent? I don't see a good reason.

Regarding your provicative comment, I'm not really concerned about your work or Gainer's work being a competition for my developers. If that were the case, why I don't have issues with Sandy King? I don't know him personally, but the way he writes and reports his work is pretty fact-oriented. He also studies similar work previously done by others before jumping the gun to claim his work novel.

What I'm concerned about is that a lot of unsubstantiated claims (and stories) disseminated frequently here, photo.net, and probably other places.

 

[Ryuji]

Is it a fact or a theory that buffer capacity is a "GOOD THING"? There are many in the literature that seem to depend upon poor buffer capacity for their touted qualities. I am not sure we can treat the TEA separately when it is used as both solvent and alkali.

Buffering is a good thing in developer formulae as far as consistency and robustness are concerned. In some applications where poor buffering can be used, it is best to use a smaller quantity of the proper agent for that pH. This way you can get the best of both worlds.

There are many alkanolamines and alkanolamine derivatives, with their buffering range from 7.5 to 10.5. I've suggested some of them to Gainer here or on photo.net. They are similar viscous liquid and can be used in a very similar way to triethanolamine.

Before you go on to attack a straw man called "theory," I will go on and say that I have formulated various ascorbate developers with those alkanolamine derivatives and some of them produced excellent robustness and accutance. Indeed, all of my current developers use a blend of two or more alkanolamines and their derivatives. Some of them I had to synthesize myself, but many of them are used in industry and they are readily available from scientific or industrial chemical dealers.

 

[gainer]

Buffering is a good thing in developer formulae as far as consistency and robustness are concerned. In some applications where poor buffering can be used, it is best to use a smaller quantity of the proper agent for that pH. This way you can get the best of both worlds.

There are many alkanolamines and alkanolamine derivatives, with their buffering range from 7.5 to 10.5. I've suggested some of them to Gainer here or on photo.net. They are similar viscous liquid and can be used in a very similar way to triethanolamine.

Before you go on to attack a straw man called "theory," I will go on and say that I have formulated various ascorbate developers with those alkanolamine derivatives and some of them produced excellent robustness and accutance. Indeed, all of my current developers use a blend of two or more alkanolamines and their derivatives. Some of them I had to synthesize myself, but many of them are used in industry and they are readily available from scientific or industrial chemical dealers.

My memory is not what it used to be. The only way I know this is that I can't remember what it used to be. Please tell me again what alkanolamines you would suggest.
I don't attack theory, but I have had experience in aeronautical research of too much blind dependence on theory, to the extent that certain wind tunnel test results were rejected as being the result of defective equipment because they did not agree with Linearized Potential Flow Theory. This conclusion was reached by some visiting faculty from one of our most prestigious engineering schools. Their error was in not looking at the wing sections being tested. They had blunt leading edges. The linearization of the theory required the assumption that wings would have sharp leading edges so that small angle approximations could be used. I have become like the monkey who always put peanuts under his tail before he ate them. The zookeeper explained that someone had given him a peach pit once and he had such a hard time passing it that now he measures everything to see if it will fit.