Improved version of DS-10 by Ryuji Suzuki?

[albada]

What does sulfite do? How much is needed for a fine grain effect? Is more better?

I noticed that when mixing developers, I'd add a little of this and a little of that, and drown it all in a large mound of sulfite. So I said "this is ridiculous", and started trying to reduce sulfite. My basic method was posted earlier as "half and double": Cut sulfite in half, and double the dev-time. But I still wondered what different amounts of sulfite actually did, so I formulated the following four developers:

Sodium sulfite ................. 22, 33, 45, 90 g
Sodium metaborate ........ 2.7, 2.4, 2.0, 1.0 g
Ascorbic acid .................. 4.5 g
Phenidone ...................... 0.05 g
Target pH=8.0. Starting times are twice XTOL's times. For TMY-2: 13 min @ 20C.

I kept the pH and dev-time the same for all of these. The results below are labeled with the amount of sulfite:

22: Too thin, and I asked about this earlier in this thread. Based on PE's reply, it appears that Tmax-400 (TMY-2) works poorly with this brew.
33: Looks good. Grain is at least as good as XTOL or a hair finer, with a hair better shadow-detail.
45: Looks good. Grain is at least as good as XTOL or a hair finer, with a hair better shadow-detail.
90: Too dense with coarser grain. Shadow-detail matches XTOL.
90 retried at 11.5 min instead of 13 min: Slightly thin, grain is a little rougher than XTOL, and there's a hair less shadow-detail.

It's hard to tell the difference between 33 and 45. I slightly prefer 45 because the grain is slightly less wormy-looking in some cases. In practice, most people could not tell the difference between these two.

My conclusions:

• Even keeping pH constant, the proportion of sulfite affects density.
• A long soak in high sulfite can make grain worse instead of better.
• You can get top quality with much less than 80-100 g/L of sulfite.

That last point is good news for my concentrate-project: It means one can get great quality without using much chemistry.

Mark Overton

[Photo Engineer]

Mark;

Great experiments. Before you know it, someone else will be selling this stuff!

You are looking at the solvent activity of Sulfite at higher concentrations and also the buffer capability (to a lesser extent).

There you are.

Sulfite is also your preservative to a certain extent, extending the life of the developer.

PE

[Michael R 1974]

Why would a long time in a sulfite-rich solution, in and of itself increase graininess? That seems odd, unless what you're seeing is simply more development taking place due to the developing agents being better preserved by the higher sulfite level, which would indeed increase graininess. But that's not "direct" action by the sulfite. Consider D25 versus D23. The only difference is the lower pH of D25, resulting in longer contact with the sulfite for finer grain than D23.

Then again I'm no chemist so take my comments for what they're worth

[albada]

Great experiments.

Ron, thanks for the note. And that makes two of us who are not watching the superbowl.

BTW, thanks for the responses yesterday about sharpness.
In my report of four developers two postings ago, I didn't mention sharpness because it's hard to see any difference among these developers and XTOL.

Yesterday, Rudeofus mentioned that SMAP is restrictive. True, but for a concentrate, I'm not restricting myself to metaborate-ascorbic-phenidone. For example, Boric acid is a worthy chemical for a concentrate, and buffers well with metaborate. TEA is another. But I'm finding that one can accomplish surprising things with only the four SMAP components, so I'm using them as my baseline for experiments.

EDIT:
Michael R 1974 responded while I was typing the above, so I'll respond here. He wrote: "Why would a long time in a sulfite-rich solution, in and of itself increase graininess?"
That's what I saw in 22X loupes for the 90-case. But on re-exam, the graininess per se is about the same, but the appearance of the grain is more "wormy" for lack of a better word. XTOL and the others have more uniform grain, but 90's grains are more often connected to each other, forming black worm-like lines. The white areas between grains can also connect, forming white worms. Obviously, I don't know what causes or prevents these worms.

Mark Overton

[Photo Engineer]

Ok, Sulfite is a silver halide solvent. Long contact with concentrated Sulfite allows many many things to happen. The simplest way to explain this is that the tiny slow grains or the low iodide slow grains will dissolve courtesy of high Sulfite. The longer you are in contact with this developer the more chance you have of depositing this silver on other developing grains in the mid tones or elsewhere. As a result, the silver metal "grains" become abnormally large due to the extra silver being deposited.

This leads to coarser grain.

There are others reasons such as the fact that solvent developers can change edge effects and change visual contrast thereby subtly altering the visual appearance of grain making it appear worse.

Many many things going on here.

PE

[Ryuji]

[...] he has enough sulfite to renew used ascorbate. If Mark wants sharpness aka edge effects, he needs to design a developer which breaks down locally from heavy use. He can do that either by using a higher dilution, by weakening his buffering (less ascobate and metaborate for same pH), reducing agitation or by making sure that oxidised ascobate won't get replaced&restored (less ascorbate&sulfite).

Oxidized ascorbates are not regenerated by sulfite. The oxidation reaction is quite complex depending on the condition, but the reaction pathways that matter in this context, the mechanism is very different from that of hydroquinone.

To be honest: designing a developer, using only four easy to obtain components, which smacks Xtol in grain, sharpness and speed in more than very few special cases sounds like a very ambitious task.

That’s right. When I look back my work in DS-10, which was intended to err slightly on the safer side with the knowledge I had at that time, knowing that pH of 8.0 was a slightly risky choice, I can simplify it a bit now, but I can only remove three ingredients (but must add one new agent) without sacrificing the stability/reliability of the developer.

[Ryuji]

Why would a long time in a sulfite-rich solution, in and of itself increase graininess? That seems odd, unless what you're seeing is simply more development taking place due to the developing agents being better preserved by the higher sulfite level, which would indeed increase graininess. But that's not "direct" action by the sulfite.

This is a very good and relevant question.

Some people here seem to jump to fallacious conclusions... many equate sulfite with solvent, solvent with physical development, physical development with fine grain effects, where each association here is problematic. For example, sulfite does a number of other things than dissolving silver halides. Solvent effect does not entail in physical development. Physical development may make larger or finer grain, often within the same emulsion and same developer. So, making a grand fallacy of sulfite = fine grain is misleading, but some seem to be trapped with it.

If the reported experiment was done very carefully, the most plausible explanation of the result is that sulfite acted as a mild “disinhibitor” or accelerator of development process, and this is well known.

[Rudeofus]

Sulfite is also your preservative to a certain extent, extending the life of the developer.

That's a nice property of sulfite but I assume Mark mixes his soups as he uses them, so preservation seems less of an issue here.

Oxidized ascorbates are not regenerated by sulfite. The oxidation reaction is quite complex depending on the condition, but the reaction pathways that matter in this context, the mechanism is very different from that of hydroquinone

Oops. Read too many articles on superadditivity and got that mixed up apparently. So much for "learn photo chemistry in 24 hours"

Yesterday, Rudeofus mentioned that SMAP is restrictive. True, but for a concentrate, I'm not restricting myself to metaborate-ascorbic-phenidone. For example, Boric acid is a worthy chemical for a concentrate, and buffers well with metaborate. TEA is another. But I'm finding that one can accomplish surprising things with only the four SMAP components, so I'm using them as my baseline for experiments.

The biggest advantage of restricted choice of ingredients is that the number of experiments doesn't go through the roof, so there's a good chance we as amateurs can even reach the optimum of what is possible with these ingredients. But lets not forget that Kodak could afford lots of engineers, lots of experiments and had lots of exotic compounds at hand so there is a good chance that Xtol will always be superior to SMAP except for a few special cases. The original question you asked about your SMAP sounded like "I beat Xtol in grain size and speed, how come it's still better in sharpness?".

Instead of beating Xtol in all respects we could focus on beating it in a few relevant parameters so we can mix and match dev depending on application. I would love to create a set of 10 recipes, all using the same set of easy to get ingredients only in different concentrations and which would cover the whole speed/grain/acutance triangle. Current recipe collections read like books about cocktail mixing, where you need 10 different ingredients for 3 cocktails and 20 if you want to mix 6 of them.

There are others reasons such as the fact that solvent developers can change edge effects and change visual contrast thereby subtly altering the visual appearance of grain making it appear worse.

Yes to that. Let's not forget that the grain we observe is not the individual silver grains but a superposition of them. A lot of things have an effect on visual grain, actual silver grain size is only one of them.

[Keith Tapscott.]

Oxidized ascorbates are not regenerated by sulfite. The oxidation reaction is quite complex depending on the condition, but the reaction pathways that matter in this context, the mechanism is very different from that of hydroquinone.



That’s right. When I look back my work in DS-10, which was intended to err slightly on the safer side with the knowledge I had at that time, knowing that pH of 8.0 was a slightly risky choice, I can simplify it a bit now, but I can only remove three ingredients (but must add one new agent) without sacrificing the stability/reliability of the developer.

Would you reveal your formula for those interested in trying it?

[Ryuji]

Would you reveal your formula for those interested in trying it?

I might be cynical here, but I'm not into publishing every little variants of so many developers I made and tried and used just because they are different. They made the same photographic effects for all practical purposes.

You might want to go to a Hong Kong restaurant, and ask your server, what's the difference between yesterday's and today's daily soup?

Then do you see the title of this thread? "Improved version of DS-10 by Ryuji Suzuki?" You don't want to see me if the title did not end with a question mark.

But one thing I can reveal now is that, the reason why I used that much TEA (and would've used more if I felt like it) and salicylic and boric acids was to increase the stability of the developer. I am ok with less of these ingredients, and zero salicylic and boric acids, only because I have a much more powerful developer stabilizer (which was used for Tektol developers after the packaging changed).