Divided developer questions

[sanking]

I don't understand this. My understanding is that the threshold of development pH of glycin is 9.0 in comparison to phenidone 6.0, metol 7.25, catechol 9.5 and hydroquinone 10.0. The based on Haist, vol. 1, p. 236.

Where does the increased pH come from in Solution A? Does a glycin solution at a given percentage have a higher pH than a metol or phenidone solution at the same percentage?

Sandy King

Also by an increase in ph. So, the reason for the glycin
A bath. Glycin is moderately active with carbonate. The
high ph will swell the gelatin while development will be
minimal. After A a TSP B bath to kick that glycin
into high gear. A carbonated metol A bath
would be to active. So no D-23.

At a higher temperature and/or ph emulsions have
a greater volume. Dan

 

[dancqu]

I don't understand this. My understanding is that the threshold
of development pH of glycin is 9.0 in comparison to phenidone
6.0, metol 7.25, catechol 9.5 and hydroquinone 10.0. That
based on Haist, vol. 1, p. 236.

Where does the increased pH come from in Solution A?
Does a glycin solution at a given percentage have a higher
pH than a metol or phenidone solution at the same percentage?
Sandy King

The A bath would be carbonated; ph apx. 10. Any one of the
the glycin - sulfite - carbonate film developer formulas might
due; eg, D-78. Dan

 

[Alan Johnson]

Experiment. APX 100 film sections were immersed for 4 min in:
(A)50 g/L sodium ascorbate,pH 6,or
(A)50 g/L sodium ascorbate,pH 11.5 (NaOH was added)
then:
(B)10g/sodium hydroxide 4 min,then fixer.
The film from the pH 11.5 solution was more blackened than that from pH 6.
Although there was some development in the part A at pH 11.5, as was seen from fixing the film without immersion in B,some of the increase in density was probably due to emulsion swelling &more developer absorbtion, which seems to apply to ascorbate too.

 

[sanking]

I am still not following something here. If you have a Bath A that contains glycin and carbonate to a pH of 10.0 the film will surely start to develop as soon as you put it in the A bath and will continue to do so until you take it out. This is not the mechanism of two-bath development as I understand it.

Sandy King

The A bath would be carbonated; ph apx. 10. Any one of the
the glycin - sulfite - carbonate film developer formulas might
due; eg, D-78. Dan

 

[Photo Engineer]

The alkaline glycin is apt to begin oxidizing as well!

PE

 

[Alan Johnson]

Some authors,eg,Thornton, use 'two bath development' to include developers that show some development in the A bath alone.In my test the proprietary two bath developer Emofin does this.

 

[Paul Verizzo]

Some authors,eg,Thornton, use 'two bath development' to include developers that show some development in the A bath alone.In my test the proprietary two bath developer Emofin does this.

This observation, which is upstream on this thread, cannot be repeated often enough. The vast majority of DD's have some development going on in Bath A, which theoretically defeats the concept and purpost.

If anyone has some Diafine out there, would you run a simple test? Put a snippet of exposed film in Bath A for three minutes and then fix. How much image? Keep in mind the film type is important, see my comments above. My notes from way back show a Diafine Bath A pH of 8.2 which is damned plenty for a phenidone based developer. Note also that Diafine has increased immersion times in Bath A for some low reactivity films.

 

[sanking]

While there is definitely development in some developers in the A bath the amount is very small compared to what happens when you plop the film into the B bath that contains the accelerator.

In two bath D23 the pH of the A solution is 8.4, that of the B solution 10.2. Considering that the threshold of development for metol is 7.25 at 4.0 grams per liter one should not expect much image formation in the A solution, and I have confirmed this with actual testing. .

The pH of the A solution of Diafine is 8.6, the B solution is 10.8. Image formation in the A solution is very limited. BTW, I am not sure what reducers are in Diafine but for sure phenidone is not the only one. I suspect that the second one is hydroquinone, which won't do anything until the pH is over 10.0. So if any image you get in the A solution will of necessity be of very low contrast.

Sandy King

This observation, which is upstream on this thread, cannot be repeated often enough. The vast majority of DD's have some development going on in Bath A, which theoretically defeats the concept and purpost.

If anyone has some Diafine out there, would you run a simple test? Put a snippet of exposed film in Bath A for three minutes and then fix. How much image? Keep in mind the film type is important, see my comments above. My notes from way back show a Diafine Bath A pH of 8.2 which is damned plenty for a phenidone based developer. Note also that Diafine has increased immersion times in Bath A for some low reactivity films.

 

[Paul Verizzo]

Sandy, yes Diafine A has hydroquinone. You can see it in the powder. While the Q might not be effective all by itself at pH of low-mid 8's, it is certainly working to keep the phenidone cranked up. In the B bath it might also be working directly.

Within a few tenths, your pH observations agree with mine.

 

[jim appleyard]

Interesting bit on using Diafine A as a stand dev:http://photo.net/black-and-white-photo-film-processing-forum/00QOGM

 

[Kino]

Well, I just got bit by the Stoeckler 2 bath formula in "The Darkroom Cookbook".

Just the barest faint outlines of images and frame spacing in 35mm.

Should have come here FIRST and read this thread!

Oh, well, it was a test 12 exposure roll of Pan F (self loaded), so no big deal.

 

[jim appleyard]

Well, I just got bit by the Stoeckler 2 bath formula in "The Darkroom Cookbook".

Just the barest faint outlines of images and frame spacing in 35mm.

Should have come here FIRST and read this thread!

Oh, well, it was a test 12 exposure roll of Pan F (self loaded), so no big deal.

I've tried all the DD from the Cookbook and found just what you did, very thin negs. It's felt that today's emulsions are just way to thin to soak up enough of the "A" bath. When was Stoekler's created? 1930?

D2D from the Cookbook and Thornton's 2-bath work well, but I would guess they've been created with today's films in mind.

 

[Kino]

I've tried all the DD from the Cookbook and found just what you did, very thin negs. It's felt that today's emulsions are just way to thin to soak up enough of the "A" bath. When was Stoekler's created? 1930?

D2D from the Cookbook and Thornton's 2-bath work well, but I would guess they've been created with today's films in mind.

Yes, I have the Thornton's book and can't for the life of me figure out why I forgot about this chapter, but when I re-read it, I felt very foolish!

Information overload Vs the impulse to act.

 

[jim appleyard]

Happens to the best of us!

It is also possible to increase the amount of dev agent in the A bath. I've done this with D23D, something on the order of 10g/liter of metol. Upon doing this, I did get decent negs.

 

[Photo Engineer]

I've said it before and I'll say it again.

Divided developers need to be optimized for just about every film or paper you use just due to thickness of the gelatin, swell due to hardening, and silver halide content due to the emulsion type used. This is a given. They can be a real pain!

PE

 

[Kino]

Well, I'm a wandering back toward D76 and like such developers!

 

[olehjalmar]

I've tried all the DD from the Cookbook and found just what you did, very thin negs. It's felt that today's emulsions are just way to thin to soak up enough of the "A" bath. When was Stoekler's created? 1930?

D2D from the Cookbook and Thornton's 2-bath work well, but I would guess they've been created with today's films in mind.

Isn't the Stoeckler recipe from the Darkroom cookbook wrong? If I remember correctly they used sodium bisulfite, which mean no development in the A bath. The original Stoeckler uses sodium sulfite and works just fine.

 

[Paul Verizzo]

Happens to the best of us!

It is also possible to increase the amount of dev agent in the A bath. I've done this with D23D, something on the order of 10g/liter of metol. Upon doing this, I did get decent negs.

I've found that increasing the developing agent(s) results in, yes, a denser negative, but very flat. Tends to overdevelop everything.

Mi dos centavos.

 

[Paul Verizzo]

I've said it before and I'll say it again.

Divided developers need to be optimized for just about every film or paper you use just due to thickness of the gelatin, swell due to hardening, and silver halide content due to the emulsion type used. This is a given. They can be a real pain!

PE

Not sure it's a given, but I certainly came to a similar conclusion.

I posted a thread here some months ago wherein I was puzzled about a DD I made. Foma 100 developed to beautiful gradations, TMY barely developed.

I have spent 20 years off and on seriously researching the literature and experimenting with DD's. My own holy grail. I have found out that it's a crapshoot, as you mentioned.

The only ones that seem to give consistent, good results are the ones that aren't truly a DD! In other words, where development takes place in Bath A. DD-23 is one such. So here comes the need for time and temperature controls again. And then someone here, IIRC, showed that the B bath didn't change anything anyway!

The DD's seem to work best with non-T/Delta grain films. Diafine and Tri-X is legendary.

My advice, as if asked for, would be to try out DD's, but be forewarned.