Divided developer questions

For a divided developer, let me propose an alternative:

Bath A:

750 ml distilled water
2.5 grams metol
55 grams sodium sulfite (a)
Water to make 1 liter (I always make 1 liter of Bath A, but
Bath B is made to order for the size
of the tank being used)

Bath B: (this gets interesting)

For 1 liter of Bath B:
750 ml of water
16 ml of HC110 OR *(see the note below)
Water to make 1 liter

Time in Bath A, 5 minutes with constant agitation
Time in Bath B, 5 minutes with constant agitation will result in a CI of
approximately .56 for many films such as 400 TMax,
100 TMax, HP5+, FP4+, 125 Plus-X, 400 TX, Delta 100,
100 Acros, APX-100, and Forte 200.
Discard the B bath after one use, use the A bath for at least 15 times,
maybe more.

* I actually began using this type of two bath development with Bath B
made up of UFG mixed 1 part stock to 4 parts water. I've also used
Accufine 1 part stock to 4 parts water. I'm sure that most any single
bath developer could be used if the correct dilution is determined.

More serious fun: Monobath (Sorta)

I've used this as a two bath developer with an incorporated fixer in the B
Bath. It was really great with all of the films listed above, with the exceptions being the TMAX films, which were more contrasty. However, at
the time I was using the B Monobath, I was using 3.5 grams of metol and 65 grams of sodium sulfite in the A Bath. It is in my plans to check the TMax films in the two bath developer with incorporated fixer with the metol and sodium sulfite reduced to 2.5 grams and 55 grams respectively.

The two bath developer with incorporated filxer was tested mixed as below:

Bath A:

750 ml distilled water
3.5 grams metol
65 grams sodium sulfite (a)
Water to make 1 liter (I always make 1 liter of Bath A, but
Bath B is made to order for the size
of the tank being used)

Bath B:

For 300 ml of Bath B:
100 ml of stock Accufine
200 ml of water
1/3 tsp of Sodium Hydroxide (Red Devil Lye)
2.5 tsp of Sodium Thiosulfate (this was pentahydrate crystals
and I think that if you use the
powder you should only use 60%
of the amount I have listed,
about 1.5 tsp.)
Time in Bath A, 5 minutes, constant agitation.
Time in Bath B, 10 minutes, constant agitation. Discard Bath B after using
once. ( I've not tried less than 10 minutes, so it could be that less time
would work)

This will eventually build up a sludge in your tank, and you will have to clean
it.

This 2 bath developer with incorporated fixer will give negatives that are very
much the same as the developer without the fixer described above.

jim appleyard said:

The "B" that Anchell lists for D2D are a combo of 37.5g of borax and 30g of carbonate, but tell the reader that more or less carbonate can be used to alter the contrast.

Anchell does list 3 "B's" for D-23D: borax, metaborate and carbonate.

Click to expand...

The B bath choice of alkali has little effect on contrast. It just develops faster. The contrast changes come with changes in Bath A. And not as much as you might think.

IDK, just passing along what's in the book.

jim appleyard said:

IDK, just passing along what's in the book.

Click to expand...

No problem, I realize that.

That's why I'm doing the experiments that I am. See my post above. Even the experts have just reiterated what others pulled out of their......parts.

Paul Verizzo said:

The B bath choice of alkali has little effect on contrast.
It just develops faster. The contrast changes come
with changes in Bath A.

Click to expand...

And what of the case where the A bath is inactive?
Anchell's few bisulfited A bath formulas are inactive
or near so. Your comment has very much the ring
of All-Things-Being-Equal.

BTW, that via Google for Stoeckler should have
been, Stoeckler Developer. Dan

Paul Verizzo said:

The B bath choice of alkali has little effect on contrast.
It just develops faster. The contrast changes come
with changes in Bath A.

Click to expand...

And what of the case where the A bath is inactive?
Anchell's few bisulfited A bath formulas are inactive
or near so. Your comment has very much the ring
of All-Things-Being-Equal.

BTW, that via Google for Stoeckler should have
been, Stoeckler Developer. Dan

Twice posted. Must be good for a second reading. Dan

dancqu said:

And what of the case where the A bath is inactive?
Anchell's few bisulfited A bath formulas are inactive
or near so. Your comment has very much the ring
of All-Things-Being-Equal.

BTW, that via Google for Stoeckler should have
been, Stoeckler Developer. Dan

Click to expand...

Actually, my most recent thoughts and experiments are with a Bath A of almost no development. And, of course, that's what a DD is supposed to do. The "DD's" with developing going on in Bath A is a hybrid and time and temperature might come into play, thus negating one of the great (two?) benefits of DD's.

There IS a difference in negative density between a low pH and a high pH Bath B, but not much in contrast. In either case, not near as much as one might think, or that the literature infers.

According to Anchell, the type of alkalie does play a part in contrast. On page 145 of TDC, he explains that in D-23D, "Borax produces the finest grain with the least contrast, metborate produces medium grain with low contrast and sodium carbonate has the highest contrast...

As for blisters in the emulsion with stop bath, Anchell goes into this on pages 34. There is also a statement from Neblette in "Photography, It's Materials and Processes". On page 235 he states, "Sodium Metaborate, unlike sodium carbonate, does not produce a gas in the presence of an acid and there is less danger of the emulsion blistering when transferred from the alkaline developer to and acid stop."

Just fyi.

jim appleyard said:

According to Anchell, the type of alkalie does play a part in contrast. On page 145 of TDC, he explains that in D-23D, "Borax produces the finest grain with the least contrast, metborate produces medium grain with low contrast and sodium carbonate has the highest contrast...

As for blisters in the emulsion with stop bath, Anchell goes into this on pages 34. There is also a statement from Neblette in "Photography, It's Materials and Processes". On page 235 he states, "Sodium Metaborate, unlike sodium carbonate, does not produce a gas in the presence of an acid and there is less danger of the emulsion blistering when transferred from the alkaline developer to and acid stop."

Just fyi.

Click to expand...

I'll bet he never tried the experiments to support what he says, which is what other authors have said.

I've done them, and he's wrong. Aristotle said a heavy object falls faster than a light one. Then Galileo came along.

The type of alkali influences the pH, and the amount is related to buffer capacity. That is why different alkalis give different results. At the same pH and a given molar equivalency, then the alkalis would behave pretty much the same.

PE

Photo Engineer said:

The type of alkali influences the pH, and the amount is related to buffer capacity. That is why different alkalis give different results. At the same pH and a given molar equivalency, then the alkalis would behave pretty much the same.

PE

Click to expand...

OK, then, to further my comments. All of my alkali solutions are well buffered in the sense of either substantial amounts of borax or sodium metaborate. I know borax is not a true buffer, but with adequate amounts behaves like a buffered solution. Big changes in concentration have only minor changes in pH after maybe 10g/liter.

I have made a buffered solution using lots of carbonate and then sodium bicarbonate to reduce pH to 10.5. No real difference that I could detect from just carbonate.

The bottom line is, presuming adequate concentration or buffering of the accelerant, the pH of Bath B will primarily effect density and secondarily contrast. Lower with increased pH. High zones stop developing because of the limited developing agents but the high pH keeps working on mid and low exposure areas to a degree. The same effect is had by having too much developing agents in Bath A. Yes, you can overdo it.

This is not book theory. These are my observations after many, many experiments.

Paul;

Conduct away! And good luck to you. Just make sure that you work out DD conditions for all types of film properly or it will be useless until you do. And, remember, films do not "see" the borate or carbonate, they "see" the negative OH ion in the developer and the positive H ion produced in the development process. This is what is causing the effects you see.

PE

Paul Verizzo said:

OK, then, to further my comments. All of my alkali solutions are well buffered in the sense of either substantial amounts of borax or sodium metaborate. I know borax is not a true buffer, but with adequate amounts behaves like a buffered solution. Big changes in concentration have only minor changes in pH after maybe 10g/liter.

I have made a buffered solution using lots of carbonate and then sodium bicarbonate to reduce pH to 10.5. No real difference that I could detect from just carbonate.

The bottom line is, presuming adequate concentration or buffering of the accelerant, the pH of Bath B will primarily effect density and secondarily contrast. Lower with increased pH. High zones stop developing because of the limited developing agents but the high pH keeps working on mid and low exposure areas to a degree. The same effect is had by having too much developing agents in Bath A. Yes, you can overdo it.

This is not book theory. These are my observations after many, many experiments.

Click to expand...

Paul,

Just a quick observation or three.

Borax itself is a much better buffer, at equivalent molarities, than either sodium metaborate or sodium carbonate, judging by their respective buffer numbers (inverse of slope at pKa). That is, it's capable of maintaining a narrow pH deviation over a wider range of added equivalents of either a weak base or weak acid.

A true 'buffer solution' comprised of an acid and its conjugate base salt isn't the subject but instead the actual buffering of the compounds listed above. Each has a different pKa, or different pKa values depending on type, and if not adjusted in pH by titration with their respective conjugate acid this would be the pH of the solution itself.

The pH of the solution will remain relatively insensitive to concentration as long as the isohydric (?) pH is close to the solution's pKa although with borax the borate molarity should be great enough for the tetraborate ion B4O5(OH)4 (2-) to dominate in solution and this is almost always the case in photographic solutions that I've seen so far.

I'm pretty sure the pH doesn't directly affect development rate but instead affects diffusion into the gelatin and thus the relative ion/anion concentration with time of the developer/accerator system. Note that there is a peak in the MQ superadditivity as a function of pH but this pH isn't necessarily found throughout the emulsion, dispersion, whatever. At least I think that's pretty much right, someone will kindly correct me if I'm out in the weeds here. And of course this peak pH doesn't apply for Metol only developers.

FWIW,
Pete

Pete;

My comments above are based on equivalent pH and molarities based on buffers such as carbonate/bicarbonate and etc. Kodalk forms a "buffer pair" in water so you need only use Kodalk.

In any event, diffusion of OH in and H out are the two most important factors in development and they are normally rapid due to size more than agitation. I have measured the pH drop to acid values from pH 10 with poor buffer capacity by using a micro surface electrode. You can actually see development progress with time, lower the pH and then see development stop.

X-ray fluorescence was used to measure the rate of development and its extent, by rapid quenching and then analysis of the dry punches of the silver step wedge. This way we could construct a pH - development rate - silver curve for a variety of buffers.

PE

Photo Engineer said:

Pete;

My comments above are based on equivalent pH and molarities based on buffers such as carbonate/bicarbonate and etc. Kodalk forms a "buffer pair" in water so you need only use Kodalk.

In any event, diffusion of OH in and H out are the two most important factors in development and they are normally rapid due to size more than agitation. I have measured the pH drop to acid values from pH 10 with poor buffer capacity by using a micro surface electrode. You can actually see development progress with time, lower the pH and then see development stop.

X-ray fluorescence was used to measure the rate of development and its extent, by rapid quenching and then analysis of the dry punches of the silver step wedge. This way we could construct a pH - development rate - silver curve for a variety of buffers.

PE

Click to expand...

Tnx for the clarification, I was thinking in terms of intrinsic buffer pairs as well e.g., sodium borate and metaborate (Kodalk, I think).

Just ordered a copy of Mees & James so I won't be so ignorant of this stuff, looks like it'll be interesting. Diffusion being more dependent on size then on agitation is something that never occurred to me but makes perfect sense, thanks very much. I guess the agitation is more for uniformity and availability of reactants to be adsorbed to the surface? Although maybe adsorb isn't quite the right term.

Starting to work with Formulary's DD-76, having made my first batch of it last night, the details of how borax in solution works got me looking stuff up. Found this http://www.borax.com/detergents/pheffect.html# while wandering around and though it doesn't show the buffer index for metaborate it does for carbonate by itself which is what I was thinking of when attempting to make a comparison.

If I'm not mistaken I think the saturation point in water for carbonates is higher than it is for borates giving them higher absolute capacity but this is about where it all goes right up to being, well, confusing... :confused:

Tnx,
Pete

Pete;

For all practical purposes, I've found Kodalk and Carbonate to be about equivalent at pH 10.1 for most purposes, as long as the molarity is adjusted to give the same buffer capacity. This is just about 50 g/l of either. I've designed dozens of developers using both and can say that stability and development rate is just about identical.

Now, there is one fact to consider. Salt effect! If you have too much salt in a developer, it inhibits swell and therefore retards development. It is death to a 2 part developer. So, adding sodium sulfate to part A or B of a DD can just about kill it. This is an extreme example, but one which illustrates the point. You can add too much total salts and inhibit swell.

OTOH, you can add swelling agents that enhance DDs. In either part A or part B, they act to swell the gelatin and absorb chemicals more and more rapidly. You have to control these or you can reticulate the film.

PE

justpete said:

If I'm not mistaken I think the saturation point in water for carbonates is higher than it is for borates giving them higher absolute capacity but this is about where it all goes right up to being, well, confusing... :confused:

Tnx,
Pete

Click to expand...

Sodium metaborate (Kodalk) and sodium carbonate have real world solubilities that max out at around 100 grams per liter, in my experience. They will dissolve, but not happily.

I can't speak for Borax, I've never tried it because after about 10g/liter the pH barely moves up.

Paul Verizzo said:

Sodium metaborate (Kodalk) and sodium carbonate have real world solubilities that max out at around 100 grams per liter, in my experience. They will dissolve, but not happily.

I can't speak for Borax, I've never tried it because after about 10g/liter the pH barely moves up.

Click to expand...

10gm/l of borax is about 0.025M, or 0.1M borate, said to be the threshold for the hydrolysis equilibrium products to be dominated by the tetrahydroxyl borate anion which yields a pKa of about 9.1 or thereabouts. Kodalk and carbonates top out around a point higher but have poorer equimolar buffer indicies so it's a tradeoff as far as I can tell between alkali pH and ml equivalent capacity.

I'm figuring on trying out sodium metaborate (at PE's 50gm/l molarity) in place of borax with the Formulary DD-76 A solution although I don't expect to see any difference other than an increase in contrast with identical times in bath B owing to the higher pH. What the heck, it'll be fun. Might order some potassium carbonate at the same time, ya' know, make a party out of it.

Photo Engineer said:

Pete;

For all practical purposes, I've found Kodalk and Carbonate to be about equivalent at pH 10.1 for most purposes, as long as the molarity is adjusted to give the same buffer capacity. This is just about 50 g/l of either. I've designed dozens of developers using both and can say that stability and development rate is just about identical.

Now, there is one fact to consider. Salt effect! If you have too much salt in a developer, it inhibits swell and therefore retards development. It is death to a 2 part developer. So, adding sodium sulfate to part A or B of a DD can just about kill it. This is an extreme example, but one which illustrates the point. You can add too much total salts and inhibit swell.

OTOH, you can add swelling agents that enhance DDs. In either part A or part B, they act to swell the gelatin and absorb chemicals more and more rapidly. You have to control these or you can reticulate the film.

PE

Click to expand...

I'll give the metaborate and carbonate a shot at 50gm/l, thanks for the tip.

Didn't know about the effect of salt on 2-baths, no sulfate for tropical temps, eh? Good thing I didn't give it a try what with the cold water tap temp at 25C this time of year. May be ok with TD-16 but w/o HQ does it matter I wonder.

Regardless, gelatin diffusion shutting down with salt added to the mix sounds like a no-go. I started using a tempering bath for all the beakers instead, adding ice struck me as less of a risk than ignurntly dinking with variations on proven formulas.

Tnx,
Pete

Pete;

Make sure that the pH values are the same. It should be adjusted to about 10.1 for both solutions. That way you get the best from both buffers for the comparison.

PE

justpete said:

I'll give the metaborate and carbonate a shot at 50gm/l, thanks for the tip.

Didn't know about the effect of salt on 2-baths, no sulfate for tropical temps, eh? Good thing I didn't give it a try what with the cold water tap temp at 25C this time of year. May be ok with TD-16 but w/o HQ does it matter I wonder.

Regardless, gelatin diffusion shutting down with salt added to the mix sounds like a no-go. I started using a tempering bath for all the beakers instead, adding ice struck me as less of a risk than ignurntly dinking with variations on proven formulas.

Tnx,
Pete

Click to expand...

I admit I only had HS chemistry and that was a looooooong time ago. While knowing more about activator and buffer solutions might have some advantage in my experiments, I don't think so. I don't need explanations for the reactions going on to see what the end results are.

IIRC, 30 grams of metaborate will give you a pH of 10.5. Fifty would be a bit more, but nothing radical. Carbonate will be a bit more pH. Carbonate will reach 10.5 with only five grams, but that's not much reserve for local action. But all this is splitting hairs as to the end result. pH 10.5 or 10.8? won't matter a whit.

Paul;

A difference of 0.3 pH units is pretty big when you consider that this is a log scale. When you adjust the solution of 10.3 to 10.1 or 10.8 to 10.1 so that they are the same pH, you are forming the appropriate buffer combination in the solution. In this case, if it were to be carbonate, then you would form a carbonate-bicarbonate buffer in exactly the right proportions to buffer at 10.1.

This is exactly how some of our developers are worked out in the lab. Then, when packaged, they use the actual sodium carbonate and sodium bicarbonate mixture that will achieve the right pH.

Knowing chemistry does help actually.

PE

Paul Verizzo said:

I admit I only had HS chemistry and that was a looooooong time ago. While knowing more about activator and buffer solutions might have some advantage in my experiments, I don't think so. I don't need explanations for the reactions going on to see what the end results are.

IIRC, 30 grams of metaborate will give you a pH of 10.5. Fifty would be a bit more, but nothing radical. Carbonate will be a bit more pH. Carbonate will reach 10.5 with only five grams, but that's not much reserve for local action. But all this is splitting hairs as to the end result. pH 10.5 or 10.8? won't matter a whit.

Click to expand...

Paul,

My apologies, I didn't mean in any way to imply as a generalization that experimentation w/o chemistry knowledge is 'dinking ignurntly with variations on proven formulas'; the comment was purely self-referential owing to my complete ignorance of suspension, dispersion, and emulsion chemistry. Knowing now that salts inhibit gelatin swelling fills in a bit of a blank there for me and I'm hoping Mees and James will help further.

Cheers,
Pete

Photo Engineer said:

Paul;

A difference of 0.3 pH units is pretty big when you consider that this is a log scale. When you adjust the solution of 10.3 to 10.1 or 10.8 to 10.1 so that they are the same pH, you are forming the appropriate buffer combination in the solution. In this case, if it were to be carbonate, then you would form a carbonate-bicarbonate buffer in exactly the right proportions to buffer at 10.1.

This is exactly how some of our developers are worked out in the lab. Then, when packaged, they use the actual sodium carbonate and sodium bicarbonate mixture that will achieve the right pH.

Knowing chemistry does help actually.

PE

Click to expand...

With all due respect, I don't think such detailed knowledge matters a whole lot for the level of precision needed for the types of experiment I have been doing. Know about pH, know about well buffered, adequately buffered, and poorly buffered solutions and that's pretty much all one needs. It's all I've needed to make some very iconoclastic observations of what many have taken as gospel for many years. Look at the classic divided developers. None of the creators knew squat, I'll bet, about these issues of buffering, etc. In fact, most of the recipes and suggestions are pure, inaccurate, guessing.

The logrithmic (sp?) pH scale seems to have very little real world influence in a DD. I have gotten good negatives with a Bath B of 9.5, and also 11. Of far more importance, I've found, is the concentration of developers in Bath A.

And probably very little effect in a single bath developer, as well, except in huge leaps and mostly at the lower end. Obviously, shorter development times come with higher pH, which is the same thing with a DD. The film doesn't behave enough differently from a pH of 9 to 9.5, say, to notice, adjusted for development time.

In all this, I'm only referring to tonality, not secondary effects like grain or sharpness.