"Improved" D-76 - thoughts?

Craig · Apr 4, 2024

I saw this formula in Patric Dignan's 150 formulas book and I quote from the write up:

"First of all, it appears that D-76, if mixed from the can or from the formula, is an unstable solution. Upon storage or use, the borax will tend to become more hydrolized and thus increase the pH. With straight D-76 and, say, Tri-X the user may notice increasing grain with older solutions. Due to the low activity of the developing· agents used, however, there is rarely a major change in contrast or film speed.

The obvious solution, we feel, is to replace the borax with a more stable buffered alkali. Due to ecological restrictions, we felt that the obvious phosphate substitutions were unsuitable. We then settled on a mixture of Sodium Carbonate and Sodium Bisulfite. Our suggested formula for what we call D-76X is as follows:

Metol 2.0 grams
Sodium Sulfite (anhy) 100.0 grams
Hydroquinone 5.0 grams
Sodium Bisulfite 3.0 grams
Sodium Carbonate (mono) 9.6 grams
Water to make 1.0 liter (pH at 70°F is 8.6)"

Can anyone with photochemistry knowledge comment on if this is a reasonable modification to the classic formula? I can get the chemicals easier than I can get ID-11 at the moment, so was wondering if this is a valid substitute for the premixed developers.

bluechromis · Apr 4, 2024

It is interesting to substitute for borax, good work. There is the D-76 H variant that omits the hydroquinone. I don't know if there would be any performance benefit to formulating that without borax compared to your formula. But it might be somewhat more ecologically friendly.
https://unblinkingeye.com/Articles/Developers/Formulas/formulas.html

Alan Johnson · Apr 4, 2024

I don't think Carbonate/Bisulfite would result in the developer having such a stable pH as would using Borax but it would work to start off with . @alanrockwood and others go into the best range for buffers in this chemistry thread:

Carbonate/bicarbonate buffer

Does anyone use a carbonate/bicarbonate buffer? The pKa for the second dissociation of the carbonic acid/bicarbonate/carbonate system is about 10.25, or maybe it's 10.23, but anyway assuming it is 10.25, an equimolar mixture of carbonate and bicarbonate should give a pH of about 10.25. I...

www.photrio.com

Nobody appears to have published the experimental verification of this although is seems likely that the major labs would have done it in the past.

btw, I think that Dignan got the source of pH change wrong, it actually comes from the oxidation of hydroquinone producing the alkaline hydroxide.

Milpool · Apr 4, 2024

Kodak published a buffered version of D-76 which I think will be more stable than this carbonate version.

Kodak’s simply increased the borax to 8g and added 8g boric acid.

Craig said:
I saw this formula in Patric Dignan's 150 formulas book and I quote from the write up:

"First of all, it appears that D-76, if mixed from the can or from the formula, is an unstable solution. Upon storage or use, the borax will tend to become more hydrolized and thus increase the pH. With straight D-76 and, say, Tri-X the user may notice increasing grain with older solutions. Due to the low activity of the developing· agents used, however, there is rarely a major change in contrast or film speed.

The obvious solution, we feel, is to replace the borax with a more stable buffered alkali. Due to ecological restrictions, we felt that the obvious phosphate substitutions were unsuitable. We then settled on a mixture of Sodium Carbonate and Sodium Bisulfite. Our suggested formula for what we call D-76X is as follows:

Metol 2.0 grams
Sodium Sulfite (anhy) 100.0 grams
Hydroquinone 5.0 grams
Sodium Bisulfite 3.0 grams
Sodium Carbonate (mono) 9.6 grams
Water to make 1.0 liter (pH at 70°F is 8.6)"

Can anyone with photochemistry knowledge comment on if this is a reasonable modification to the classic formula? I can get the chemicals easier than I can get ID-11 at the moment, so was wondering if this is a valid substitute for the premixed developers.

Craig · Apr 4, 2024

Alan Johnson said:
btw, I think that Dignan got the source of pH change wrong, it actually comes from the oxidation of hydroquinone producing the alkaline hydroxide.

Based on PE's comments in the linked thread, I'm sure you're right.

DeletedAcct1 · Apr 14, 2024

Craig said:
I saw this formula in Patric Dignan's 150 formulas book and I quote from the write up:

"First of all, it appears that D-76, if mixed from the can or from the formula, is an unstable solution. Upon storage or use, the borax will tend to become more hydrolized and thus increase the pH. With straight D-76 and, say, Tri-X the user may notice increasing grain with older solutions. Due to the low activity of the developing· agents used, however, there is rarely a major change in contrast or film speed.

The obvious solution, we feel, is to replace the borax with a more stable buffered alkali. Due to ecological restrictions, we felt that the obvious phosphate substitutions were unsuitable. We then settled on a mixture of Sodium Carbonate and Sodium Bisulfite. Our suggested formula for what we call D-76X is as follows:

Metol 2.0 grams
Sodium Sulfite (anhy) 100.0 grams
Hydroquinone 5.0 grams
Sodium Bisulfite 3.0 grams
Sodium Carbonate (mono) 9.6 grams
Water to make 1.0 liter (pH at 70°F is 8.6)"

Can anyone with photochemistry knowledge comment on if this is a reasonable modification to the classic formula? I can get the chemicals easier than I can get ID-11 at the moment, so was wondering if this is a valid substitute for the premixed developers.

Excuse me but a buffer in chemistry is a conjugate acid-base pair, meaning either a. a weak acid and its conjugate strong base, or b. a weak base and its conjugate strong acid.
Sodium carbonate/sodium bisulfite is not a buffer at all.

beemermark · Apr 14, 2024

I have no clue who Patric Dignan's is but D76 is a generic film developer that was developed based on Kodak producing a more stable developer to D23. All in all no matter how many times you mix and mash the same chemicals it's all the same. I'm going to look him up but everyone is chasing the pot of gold at the end of the rainbow IMHO.

Craig · Apr 14, 2024

beemermark said:
I have no clue who Patrick Dignan is

See this thread and the link to the PDF of the book: https://www.photrio.com/forum/threads/dignans-150-photographic-formulas.18436/#post-2779140

Philippe-Georges · Apr 15, 2024

bluechromis said:
It is interesting to substitute for borax, good work. There is the D-76 H variant that omits the hydroquinone. I don't know if there would be any performance benefit to formulating that without borax compared to your formula. But it might be somewhat more ecologically friendly.
https://unblinkingeye.com/Articles/Developers/Formulas/formulas.html

Here the D-76 becomes a human friendly E-76 by omitting hydroquinone and metol, by Chris Patton from Stanford.edu:

Alan Johnson · Apr 15, 2024

Alessandro Serrao said:
Excuse me but a buffer in chemistry is a conjugate acid-base pair, meaning either a. a weak acid and its conjugate strong base, or b. a weak base and its conjugate strong acid.
Sodium carbonate/sodium bisulfite is not a buffer at all.

Yes, strictly what is being discussed is the buffer capacity as illustrated around p25 here:

https://www.kodak.com/content/products-brochures/Film/Processing-KODAK-Motion-Picture-Films-Module-3.pdf

koraks · Apr 15, 2024

Alessandro Serrao said:
Sodium carbonate/sodium bisulfite is not a buffer at all.

Indeed; I assume that this is either a transcription error or an erratum in the original Dignan book quoted by @Craig, and that a carbonate/bicarbonate buffer is intended. If this is the case, it's a bit of an unfortunate choice since the buffer capacity of such a buffer isn't the greatest at the desired pH:

(source)
It'll work, to an extent, but it's not optimal. The main advantage of a carbonate/bicarbonate buffer in this application is that it uses such commonly available materials, and hence, it can be mixed a little stronger to compensate for the suboptimal buffer capacity at the selected pH.

Milpool · Apr 15, 2024

D-76 pre-dates D-23.

beemermark said:
I have no clue who Patric Dignan's is but D76 is a generic film developer that was developed based on Kodak producing a more stable developer to D23. All in all no matter how many times you mix and mash the same chemicals it's all the same. I'm going to look him up but everyone is chasing the pot of gold at the end of the rainbow IMHO.

Don_ih · Apr 15, 2024

koraks said:
I assume that this is either a transcription error or an erratum

It's mentioned twice in the article (by Milan Merhar - not actually written by Dignan), so it seems like what they chose.

Craig said:
Can anyone with photochemistry knowledge comment on if this is a reasonable modification to the classic formula?

The best thing to do is mix a litre of this stuff and try it over the course of a month.

Rudeofus · Apr 15, 2024

Alessandro Serrao said:
Excuse me but a buffer in chemistry is a conjugate acid-base pair, meaning either a. a weak acid and its conjugate strong base, or b. a weak base and its conjugate strong acid.
Sodium carbonate/sodium bisulfite is not a buffer at all.

It may not be a buffer in the classical sense, but it sure as heck acts as a buffer. You have both the sulfite/bisulfite pair, and the carbonate/bicarbonate pair in this mix, and can adjust a moderately stable pH in a wide range of photographically useful pH levels.

Nicholas Lindan · Apr 15, 2024

IIRC, Richard Knoppow posted that the D-76 stability problem was fixed by Kodak in the year after the developer was introduced - sometime in the 1920's. B&W movie production needed a very stable process so that shots taken a month apart could be spliced together without any shift in density or contrast.

In general it seems the formula that Kodak put in the can wasn't necessarily the same as the published DIY formula. I don't know if Kodak ever published the formula for their commercial, packaged D-76.

The general consensus is that the pH was stabilized by using boric acid in addition to borax, as noted above. That's what most DIY'ers use and it seems to work well with no shift in activity. I've used it hours after mixing and months later without any noticeable shift. Of course, I did not run any controlled tests.

Considering Kodak's love affair with metaborate (AKA Kodalk) this chemical may also have been involved. This could all be answered with a mass spectrometer, anyone have one?

Keith Tapscott. · Apr 15, 2024

Both Kodak and Ilford have probably tweaked the formula over the years, but their modifications will most likely remain as trade secrets.

Milpool · Apr 15, 2024

The ingredients listed on the packages are fairly complete. Some minor adjustments to D-76 seem to have been made over time. I doubt ID-11 has changed (it also contains fewer compounds than packaged D-76 to begin with as ID-11 isn’t in a single packet).

Slightly off topic but anyone remember ID-11 Plus?

I don’t think Kodak ever sold pre-packaged D-76d but I could be wrong.

Randy Stewart · Apr 16, 2024

beemermark said:
I have no clue who Patric Dignan's is but D76 is a generic film developer that was developed based on Kodak producing a more stable developer to D23. All in all no matter how many times you mix and mash the same chemicals it's all the same. I'm going to look him up but everyone is chasing the pot of gold at the end of the rainbow IMHO.

Back in the 1970s, before the Age of the Internet, several people with some knowledge of the chemistry underlying film photography published subscription newsletters covering photochemistry subjects. Pat Dignan was one of those. He leaned toward formulas for processing solutions which were not commonly available, as well as modifications thereof and experimental items. He also published several soft bound booklets which usually summarized information from those newsletters. His "150 B&W Formulas" was probably the most widely distributed. Consider it an early form of "The Darkroom Cookbook". I think he was also the original publisher of "Darkroom Photography", a slick monthly magazine covering much the same subjects, but drawn from a wider and usually better researched resources and contributors.

Keith Tapscott. · Apr 16, 2024

Milpool said:
The ingredients listed on the packages are fairly complete. Some minor adjustments to D-76 seem to have been made over time. I doubt ID-11 has changed (it also contains fewer compounds than packaged D-76 to begin with as ID-11 isn’t in a single packet).

Slightly off topic but anyone remember ID-11 Plus?

I don’t think Kodak ever sold pre-packaged D-76d but I could be wrong.

I think that ID11 Plus was only sold in the USA. I don't know how it differed from the standard product.

Milpool · Apr 16, 2024

I once found a 1980's SDS for it somewhere. If I remember correctly the magic ingredient was cinnamic acid (disulfide) - presumably to help prevent/minimize sludging of dissolved silver in machines. Various compounds were used in developers over the second half of the century for this purpose - also to reduce the risk of dichroic fog - but they eventually became redundant and/or detrimental as emulsions evolved to obviate the need.

Keith Tapscott. said:
I think that ID11 Plus was only sold in the USA. I don't know how it differed from the standard product.

Rudeofus · Apr 16, 2024

Milpool said:
The ingredients listed on the packages are fairly complete. Some minor adjustments to D-76 seem to have been made over time. I doubt ID-11 has changed (it also contains fewer compounds than packaged D-76 to begin with as ID-11 isn’t in a single packet).

There are many variations of D-76 around, some as the traditionally known one, others with Borax/Boric Acid buffers. The difference between ID-11 and D-76 is not the number of photographically active ingredients: Kodak developed and applied special techniques for manufacturing coated powder particles. As you may remember: the Metol has to dissolve before the bulk of the sulfite, therefore the sulfite needed some coating which delays its dissolution in water.

This allowed Kodak to make a (commercially more attractive) single powder D-76 pack.

NB23 · Apr 16, 2024

Craig said:
I saw this formula in Patric Dignan's 150 formulas book and I quote from the write up:

"First of all, it appears that D-76, if mixed from the can or from the formula, is an unstable solution. Upon storage or use, the borax will tend to become more hydrolized and thus increase the pH. With straight D-76 and, say, Tri-X the user may notice increasing grain with older solutions. Due to the low activity of the developing· agents used, however, there is rarely a major change in contrast or film speed.

The obvious solution, we feel, is to replace the borax with a more stable buffered alkali. Due to ecological restrictions, we felt that the obvious phosphate substitutions were unsuitable. We then settled on a mixture of Sodium Carbonate and Sodium Bisulfite. Our suggested formula for what we call D-76X is as follows:

Metol 2.0 grams
Sodium Sulfite (anhy) 100.0 grams
Hydroquinone 5.0 grams
Sodium Bisulfite 3.0 grams
Sodium Carbonate (mono) 9.6 grams
Water to make 1.0 liter (pH at 70°F is 8.6)"

Can anyone with photochemistry knowledge comment on if this is a reasonable modification to the classic formula? I can get the chemicals easier than I can get ID-11 at the moment, so was wondering if this is a valid substitute for the premixed developers.

It was an old darkroom trick to always season D76, add some old to freshly mixed. Negatives always looked better with old D76.

Milpool · Apr 16, 2024

Yes that’s correct. I wasn’t suggesting packaged D-76 had more photographically active ingredients than ID-11, just that ID-11 doesn’t need the additional compounds Kodak employed to enable single packet packaging.

Rudeofus said:
There are many variations of D-76 around, some as the traditionally known one, others with Borax/Boric Acid buffers. The difference between ID-11 and D-76 is not the number of photographically active ingredients: Kodak developed and applied special techniques for manufacturing coated powder particles. As you may remember: the Metol has to dissolve before the bulk of the sulfite, therefore the sulfite needed some coating which delays its dissolution in water.

This allowed Kodak to make a (commercially more attractive) single powder D-76 pack.

john_s · Apr 16, 2024

The later addition of the borax/boric acid buffer would help if reusing or replenishing. Not so much needed for single shot use.

Augustus Caesar · Apr 16, 2024

Rudeofus said:
There are many variations of D-76 around, some as the traditionally known one, others with Borax/Boric Acid buffers. The difference between ID-11 and D-76 is not the number of photographically active ingredients: Kodak developed and applied special techniques for manufacturing coated powder particles. As you may remember: the Metol has to dissolve before the bulk of the sulfite, therefore the sulfite needed some coating which delays its dissolution in water.

This allowed Kodak to make a (commercially more attractive) single powder D-76 pack.

DuPont sold 6-D in cans, which was basically D-76, but I can't remember if it was a single powder or not.

"Improved" D-76 - thoughts?

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