Divided Developer question

<p><br /> I have been trying out some divided developer formulas and films. One thing I have read over and over is: “little or no development takes place in then A bath. Developer is just adsorbed by the emulsion in the A bath. Development takes place in when the film is added to the alkaline B bath”. I have NOT found this to be true. In my trials the main thing that seems to limit development in the A bath is the fact that film is only in it for 3 to 4 minutes. If I leave film in the A bath for a normal development time of 8 minutes and give standard adgitation<em></em> <em><em></em> </em> every 30 seconds I get a roll of film that is quite developed. <br /> <br /> It seems to me that the way you get compensation with divided developers is by removing the developer after half the normal time and then doing a soft stop in bath B.<br /> <br /> Results vary but in general that is my conclusion.<br /> Films tested are Plus-X, Acros and Hp4+<br /> Developers tested Divided D76, Divided D23 and Diafine<br /> <br /> Has anyone else reached the same conclusion? <br /> If so what developer and film combo works for you with a soft stop (maybe just water will do instead of a basic B bath)</p>

<p>There are divided developers where close to zero develpment takes place in the A bath because the pH is not high enough or because development is inhibited by other means (a large dose of sugar seems to work), but what you say about development in the A bath is true for others, like Stoeckler and divided D-23. But I think that you will find that a watrer B bath does not work as well, because it has to do its work before the developer from the A bathdiffuses out of the emulsion. I did some experiments with developers where little or no development takes place in the A bath based on the formulas in The Film Developing Cookbook, but they seem to give either uneven development, excessively low contast, or both.</p>

<p>Hi Brian, I am a big advocate of stand development, which performs much like a divided developer (see my profile for a book I wrote about it<g>). Either method is essentially developing to maximum detail for highlights (the densest part of the neg), but letting an exhausted (or in split developing, a highly dilute) amount of developer to work out the shadow areas.</p>

<p>As far as films, you are right on the money. I find Acros to be best for many reasons outlined in my book, but I would also add Rollei Retro and Pan-F to your list.</p>

<p>As for developers, do some exploration around non-solvent developers, like Rodinal. One of the most effective combinations I've found is to mix 1 part regular XTol (solvent developer) with 4 or 5 parts of water (depending on the film), and fairly dilute Rodinal.</p>

<p>I have not found split developing to be more effective than stand development; the results are very similar. The exception to this is on films that tend to fog and get grainy (higher ISO films). I would use split development for those. Also if you have access to just solvent developers, or you need finer grain on 35mm film. So my recommendation is Acros exposed at ISO 100, 1 part Xtol to 4 parts water, then add 5ml Rodinal and stand develop for 2 hours after 5 minutes of normal agitation.</p>

<p>1 part Xtol to 4 parts water, then add 5ml Rodinal<br>

What is the total volume that the 5ml Rodinal is added to?<br>

Is it a liter?</p>

<p>Hi Brian,</p>

<p>The reason us that solution A, the actual developer, is un-activated, sometimes actually acidified for that purpose. The B solution is only activator with no developing agent and so it permits the development of the soaked up developing solution. Be sure to give the second solution an adequate time for it to function, low level exposure may take 3 to 5 minutes to develop while the high density areas will "wear out" in 15 to 20 seconds.</p>

<p>Lynn</p>

<p>Brian, it doesn't matter, but as an example, if you want about 1 liter, then 200ml Xtol, and 800ml water, then add the Rodinal.</p>

<p>It depends on the contents of bath A. For instance, in divided D-23 the first bath is actually plain D-23, so normal development takes place.</p>

<p>However, in divided D-76 the first bath only contains 2g of metol (as opposed to 7.5 in D-23), and the hydroquinone doesn't function at that pH. So bath A behaves like very diluted D-23. You still get some development in bath A, but slower than in the case of divided D-23 due to the lower concentration of metol.</p>

<p>I think you could go even further than that. You could make divided D-76 with phenidone instead of metol. Something like: sulfite 100g, hydroquinone 5g, phenidone 0.4g for bath A, and borax 2g for bath B. I don't know, I haven't tried the formula myself, I've just invented it, but I see no reason why it shouldn't work. :-)<br /> Phenidone doesn't work by itself (not significantly, at least); it only works in conjunction with other developing agents. Without borax (or any other accelerator), the hydroquinone doesn't work. This means phenidone doesn't work. So in this case I believe you'd get almost no development in bath A.<br /> But I can't swear to it. It's just a guess. I haven't tried it.</p>

<p>Actually, now that I think about it, I think you might need a stronger accelerator than borax. Some say that in D-76, due to the relatively low pH, the hydroquinone merely replenishes the metol and doesn't really do any developing work. The pH of D-76, though high enough for the metol-hydroquinone combination, might be too low for the phenidone-hydroquinone version.<br /> But on the other hand there are PQ developers with borax, so maybe I'm worrying for nothing.<br /> I don't know, It would be fun to experiment. I think I'll try it sometime.</p>

<p>I was using the Photographer’s Formulary Version of Divided D-76.<br /> It has 4 g M and 7.5 g HQ.<br /> That may be why I was getting significant development in Solution A.</p>

<p>Indeed, there are several versions of divided D-76. I was talking about the simplest one, the one where regular D-76 is simply split in two: metol 2g, sulfite 100g, hidroquinone 5g in bath A, and borax 2g in bath B. It should still give you some development in bath A, but significantly lower than divided D-23. It should be approximately equivalent to D-23 diluted 1+3. And if you replace metol with phenidone you should get even less development in A, while still getting a normally working developer in B. At least that's what I think. Maybe someone who has actually tried it could confirm this.</p>

<p>It is true that some development occurs in Bath A of most divided developers. This depends on the the contents. In general, the more sodium sulfite, the greater the development. Sodium sulifte is generally used as a preservative in developers but it can also act as a weak alkali, increasing the pH and hence development.</p>

<p>The goal of divided developers isn't to eliminate development in Bath A per se but rather to minimize it to a point whereby the two bath system produces consistent development for a wide range of films without significant risk of over/under development. </p>

<p>If you want greater control of development (e.g., more contrast, less contrast, more grain, less grain, etc.) depending on the film, exposure or subject matter -- or if you use the zone system -- then two bath developing is not for you.</p>

<p>I have had fun experimenting with two bath developers and trying variations of Stoeckler's and Thorton's. Most of this has come out of my background in chemistry, but in turn, it has helped me to understand how developers work and how the different variables affect the final negative.</p>

<p>Nope. I was wrong. It doesn't work as I expected.<br /> I prepared the developer as follows:<br /> Bath A: sulfite 100g, hydroquinone 5g, phenidone 0.4g.<br /> Bath B: borax 2g.</p>

<p>I exposed a roll of FP4+ under the same conditions - simply made ten identical exposures in a row, then cut the film in two in the darkroom and developed each half separately.<br /> The first half was developed in bath A for 5 minutes with intermittent agitation (continuous during the first 30 seconds, then five inversions every minute).<br /> The second half was developed in bath A for 5 minutes with intermittent agitation, then bath B for 5 minutes with no agitation at all, not even in the first 30 seconds.</p>

<p>The second half of the film looks very well. Good detail in the shadows, no blocked highlights. Easy to print.<br /> The first half has been developed, too. It's clearly underdeveloped, with very thin shadows, and highlights that look like zone V to the naked eye - I don't have a densitometer. However, it looks printable. It may take a no. 5 filter and a concentrated developer, but it can be printed. I have printed negatives looking worse than that.</p>

<p>So, it looks like a fair amount of development takes place in bath A. I think the pH of the sulfite is high enough to activate the hydroquinone.</p>

<p>OK, back to the drawing board. Maybe I could get zero activity in bath A if I used ascorbic acid as a preservative instead of sulfite ? Who knows... I'll have to try it. :-)</p>

What you just used is not a divided developer, no matter what it was called. The first part is a developer in it's own right with the sulfite providing enough ph to start activity. What it is is actually a boosting in the second part. To make it a true two stage developer, some form of acid (usually bisulfite) needs to be applied to the first part to reduce the ph to about 5 or less.

As far as I know, the most popular divided developer is Diafine.

 

Some have said that a small amount of development is done in A, and I presume it

would be easy to test.

 

You are cautioned to keep B out of A, even a small amount is bad.

 

Diafine has always claimed to develop all films to the optimal contrast (or something like that).

 

I am not so sure that it is as optimal for newer films as older ones. Many newer films have only

a small EI increase, compared to older films.

What you just used is not a divided developer, no matter what it was called

- Just used?

This thread is 10 years old!

 

But yes, a classic divided developer contains little or no accelerator (alkali) in the first bath and minimal preservative (sulphite), otherwise you have a simple metol-sulphite developer.

 

Divided D-76 is just a nonsense, since the sulphite is integral to its solvent and physical development action. Likewise with 'divided' D-23. Solution A is D-23 in totality, and bath B is an added accelerator that turns it into an entirely other formula.

 

What might be interesting would be a two part Phenidone-Ascorbate developer, since neither Phenidone nor Sodium Ascorbate alone have any useful developing properties. But I'll leave that one to somebody with time on their hands, and the inclination to waste it!

- Just used?

This thread is 10 years old!

 

But yes, a classic divided developer contains little or no accelerator (alkali) in the first bath and minimal preservative (sulphite), otherwise you have a simple metol-sulphite developer.

 

Divided D-76 is just a nonsense, since the sulphite is integral to its solvent and physical development action. Likewise with 'divided' D-23. Solution A is D-23 in totality, and bath B is an added accelerator that turns it into an entirely other formula.

 

What might be interesting would be a two part Phenidone-Ascorbate developer, since neither Phenidone nor Sodium Ascorbate alone have any useful developing properties. But I'll leave that one to somebody with time on their hands, and the inclination to waste it!

 

 

Not me!

 

 

I’m no chemist, but I have used divided ‘Adams’ and ‘Thornton’ 2 baths for years, purely out of convenience. They last for ages, are simple to make up yourself, if you are that way inclined, and are relatively cheap, if you are that way inclined. Having thrown in the fixer by mistake before the second bath on one occasion, I can vouch for the fact that bath A in isolation does indeed work as a developer on its own.

Having given this some more thought; I'm beginning to question the accepted explanation for how a two-bath 'compensating' developer works.

 

The perceived wisdom is that developing agent(s) is/are absorbed into the emulsion and only activated in the 2nd bath.

 

This may have worked with old 'thick' emulsion coatings, but I'm doubtful that a modern thin and pre-hardened gelatine coating could absorb enough developer to form anything but a very faint image.

 

More likely that carry-over clinging to the film surface is what's activated in the second bath, or that the second bath simply dilutes an already activated developer and effectively becomes a slow acting stop bath. I favour this second explanation, since it's well-known that simply using a water bath after curtailed development gives an equally effective compensating action.

 

The acid test (literally) would be to make the 1st bath slightly acidic such that no development was possible, and have the 2nd bath as accelerator only.

 

This could be done by using sodium or potassium metabisulphite as the preservative in the 1st bath, together with developing agent(s). The 2nd bath would then consist of a carbonate + sulphite solution, and possibly a small amount of restrainer.

 

Of course, if this worked, it still wouldn't decide if emulsion absorption or simple carry-over (or both) was responsible for introducing the developing agent to the accelerator bath. But IMHO it would be a step in the right direction toward proving or disproving the worth of 'divided' developers over a simple water bath.

 

Another theoretical explanation for divided developer action is that developer molecules electronically attach themselves to exposure sites on AgX crystals, ready to be activated or triggered when the pH is raised above a certain level. In other words the mechanism is adsorption rather than absorption. However, researching this is above my pay-grade as a purely amateur photo chemist.