Ascorbic acid with no other developer in the mix?

albada

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I'll start with the result and my question first. I mixed 50 ml of a developer based on this formula: 60 g/L sodium carbonate (anh) and 20 g/L ascorbic acid. This soup blackened a film leader in 15 minutes.

My question: Has anyone heard of or used a developer consisting of ascorbic acid and no other developing agent?

As background, I was reading the article, "The Genesis of Xtol" (Photo Techniques, Sep-Oct 1999), and encountered these paragraphs:

Enter serendipity. Among the developing agents Silvia explored in the search for better solubility was ascorbic acid and its derivatives (one of which, as is well-known, being Vitamin C). These indeed offered easy solubility, but, significantly, she was also finding DQE values [a measure of overall image-quality] that clearly exceeded the best that could be achieved with hydroquinone-based mixes!​
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[skip down a few paragraphs]​
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It has long been known that derivatives of ascorbic acid can be used to develop camera-speed black-and-white films. Their primary failing had been in the area of shelf life: They worked fine when freshly mixed but deteriorated quickly. Experimentation showed that that failing could be overcome by formulating the mix at a near neutral pH rather than the decidedly alkaline values characteristic of earlier formulas. Unfortunately that produced a much less reactive solution with exceedingly long development times. That problem was, in turn, overcome by incorporating a small amount of a phenidone derivative. This proved superadditive with the ascorbate and brought development times back to acceptable values. [...]​

As this point, it appears that Sylvia's original formulas that produced such good image quality were based solely on ascorbate and no secondary developer. I mixed the dev described above in order to verify that ascorbic acid in a rather alkaline solution could in fact develop film.

Kodak would not accept a soup that would be short-lived. But we can accept it, if we mix from concentrate and use the working solution soon, one-shot. We know that ascorbic acid has good longevity when dissolved in glycol, so such a soup is feasible for us. Has anyone tried this ascorbic-only approach?

Mark
 

koraks

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albada said:
Has anyone heard of or used a developer consisting of ascorbic acid and no other developing agent?
Click to expand...

Nope. I believe it has been discussed a couple of times, but that the outcome was always "use ascorbate as part of a superadditive pair and as the 'replenisher' of the primary developer, typically phenidone". Please do correct me if I'm wrong; I may recall inaccurately. I think some tests may have done, but I don't recall ever having read a developer formula that was used in real-life practice beyond the scope of some clip tests - let alone a commercially available product.

albada said:
As this point, it appears that Sylvia's original formulas that produced such good image quality were based solely on ascorbate and no secondary developer.
Click to expand...

You got a point there.

The quantities you used in your test don't seem to be outlandishly high, which is what I would have expected for an ascorbate-only developer. Given your 15-minute leader-blackening time, I suspect it may be necessary to perhaps double the ascorbic acid to get back to development times that are a bit more acceptable to most (i.e. around the 10 minute mark, or shorter).

Have you performed further tests already? I'd be curious to see how this developer would compare to others. Doesn't really matter which - anything you've got sitting around would do
 

relistan

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Mark, we did some experiments with it as a control when testing the superadditivity of quercetin with ascorbic acid. Alan posted some results here: https://www.photrio.com/forum/threa...ops-like-pyrogallol.82705/page-4#post-2630597

The main things I had read about it is that it’s quite a fogging developer, and it needs pH over 10 to be active. In that same thread I linked, @Alan Johnson posted a Pourbaix chart with the reduction potential vs pH, which may be of use.

I think it’s worth experimenting with. It is not really analogous to hydroquinone at all even though it often can substitute for it as a secondary agent. If you can control the fog and get decent grain at high pH—or improve activity at lower pH—you may get a decent developer.
 

Rudeofus

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Kodak has used ascorbate developers internally for decades before the release of XTol. Ascorbate offers some improvements in sharpness, because unlike HQ, its oxidated product does not form another molecule capable of developing. Kodak was quite fixated on sharpness, much more than on grain, because many studies suggested, that sharpness was what customers really wanted in an image. Countless and endless threads of "is this lens sharp" in digital photography gear forums are solid evidence of this preference.

At the same time it must have been extremely obvious to Silvia, that an ascorbate developer would need a primary developer, and Dimezone-S was certainly not found through "serendipity", it has been used almost exclusively for decades by then. It should also be stated, that the near neutral pH of their ascorbate dev was not the primary reason for its long shelf life. It's the DTPA, which stops the Fenton reaction.

I have read this "The Genesis of XTol" article a few times, and the only conclusion I drew from this article "this was most likely not the genesis of XTol" and "Whom are they trying to deceive with this article?".
 

Alan Johnson

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Pat Gainer was not keen on the fog:

Modern Rodinal Substitutes Part II

BTW, Guys going through all this posts, I also tried to mix some Rodinal. I used this recipe: Sol A: water 500ml p-aminophenol 50g potassium metabisulfite 150g Sol B: water 300ml Sodium hydroxide 100g Sol C: water 50ml Potassium Bromide 5g Sodium benzenesulfonate 0.3g This recipe comes from...
www.photrio.com
 

nmp

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There is some discussion on using pure ascorbic acid as film developer in this thread:

Herb developer

It's been a long time since that Fomapan 100 (2003-2004), but pretty sure I agitated just like regular developer -- 5 inversions at the top of each minute after continuous the first minute. Do invert gently, as the mixed developer is slightly prone to foaming.
www.photrio.com

:Niranjan
 
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albada

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Thank you for pointing me to that thread! Your experiments show that carbonate + ascorbic acid are a reasonable developer. The article I quoted and Haist both say that AA is unstable at its high working pH. I tried developing more leader 15 minutes later, which came out weak, so the soup was weak even after only 15 minutes. Thus, one-shot would be the only hope for that developer. Also, I used hard water, which soon formed much precipitate due to the high pH. To avoid getting those particles on the film, one would need to either (1) let the beaker sit a while with a carbonate solution (no AA), and then decant it, or (2) add a sequestering agent such as DTPA, or (3) use distilled or DI water. (1) is too much bother, (2) is difficult to source, and (3) adds cost. My conclusion: AA alone is not worth the bother, despite the appeal of its D-23-like simplicity.

The observations of @Rudeofus are perceptive. If Kodak had been experimenting with ascorbates and Dimezone S for decades, then the discoveries described in the article had also been made long ago.

Mark
 

MattKing

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I've always read the "Genesis" article to be as much about making the technology a commercially viable option as anything else.
 

Rudeofus

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Ascorbates may be less stable at higher pH, but that's true for most development agents. Take a regular PQ type film developer, add 10 g/l NaOH and watch the liquid go dark.

I would like to add one point to the discussion about "low pH of XTol": all these sequestering agents (phosphonic aicds, DTPA) quit working at high pH, because they high OH- concentration competes with the sequestering agents for iron and copper ions. If you look at "sequestering strength vs. pH" charts, you will see all these agents become quite weak above pH 9.

So this may have been a key discovery back then: unlike previous ascorbate concoctions lower pH to 8.something, this allows the DTPA to sequester iron and copper well enough to keep the ascorbate stable.
 

nmp

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albada said:
Thank you for pointing me to that thread! Your experiments show that carbonate + ascorbic acid are a reasonable developer.
Click to expand...

it wasn't I who did that work, but @npl. I have not done any film development with ascorbic acid but did do a bit of paper development - not the conventional gelatin silver, but POP and more recently with developed-out salted paper where I used K bicarbonate as the alkali:

CD-POP: Chemically Developed-out Salted Paper Printing Using Vitamin C Developer

The Background: Developed-out salted paper prints go as far back as 1850’s, credited to Louis Désiré Blanquart-Evrard. Typically it involved a short exposure forming a hint of an image on salted paper followed by development with gallic acid and some silver nitrate to facilitate the physical...
www.photrio.com

As expected when sodium carbonate was used, the developer oxidized pretty quickly, but with bicarbonate it seems to be far more stable. After nearly two months, the stock solution is still water-clear (one of these days I will go back and use it again to check if it is still as active as when it was freshly made.) Of course the speed is much lower with the bicarb, so that would be one consideration, if important, in film development. In my case, I actually wanted to slow down the development to more controllable rates so it didn't bother me.



Using distilled water isn't such a bad deal - with price less than a buck for a
gallon, it will come to pennies for a batch. Better to do that than bothering with decanting, sequestering etc. I wouldn't consider that to be a show-stopper. Nor would the one-shot usage. Ascorbic acid dissolves pretty quickly. One can make a working solution of the alkali beforehand and then simply add to the acid prior to use.


:Niranjan.
 

nmp

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Rudeofus said:
Ascorbates may be less stable at higher pH, but that's true for most development agents. Take a regular PQ type film developer, add 10 g/l NaOH and watch the liquid go dark.
Click to expand...

Developing/reducing capacity goes hand-in-hand with the stability (or lack thereof.) If something reduces more effectively, then it will have a greater propensity to get oxidized as well. It's kind of a Catch-22, that way...

:Niranjan.
 
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npl

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albada said:
My conclusion: AA alone is not worth the bother, despite the appeal of its D-23-like simplicity.
Click to expand...

Same conclusion here. Pure ascorbic acid is not cheap, and my very limited experiment (in the "Herb developer" thread) at least showed that you need quite a lot of it to have correct density and short dev times. I'm more interested in using AA in small quantity with others relatively cheap, common, and environmentally friendly developing agents (I intend to pick up my thyme experiment where I left it this comming months).

But it could be worth experimenting and as koraks said, compare the result with common commercial developers. Several posts here complain about the fogging, would adding KBr (or iodized salt) help ?
 
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albada

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npl said:
Several posts here complain about the fogging, would adding KBr (or iodized salt) help ?
Click to expand...

However, in your thread, its fog looked no worse than other concoctions you tried. Did you notice extra fog with AA?

Mark
 

Rudeofus

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A while back I made a print developer from beer, Ascorbic Acid and carbonate. It actually worked, but it did reek to high heaven.
 

npl

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albada said:
However, in your thread, its fog looked no worse than other concoctions you tried. Did you notice extra fog with AA?

Mark
Click to expand...

Looking at the pictures again, I don't see more fogging in the AA strip. Maybe those who experienced fog used high speed film (>= 400 ISO)? I used a 100 ISO one.

Caffenol is known to fog high speed film, that's why KBr is added in C-CH. Would make sense to have the same problem with only ascorbic acid.
 

Sirius Glass

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If it were just that easy Ilford and Kodak would not have spent all the money in Research and Development for XTOL and its equivalents.
 
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albada

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Rudeofus said:
A while back I made a print developer from beer, Ascorbic Acid and carbonate. It actually worked, but it did reek to high heaven.
Click to expand...

I'm curious. I understand the purposes of carbonate and AA, but how did the beer help? Does alcohol confer a benefit?
 

relistan

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albada said:
I'm curious. I understand the purposes of carbonate and AA, but how did the beer help? Does alcohol confer a benefit?
Click to expand...

Beer contains phenols and other molecules that are likely superadditive with ascorbic acid. We found that milligram amounts of quercetin (e.g. in coffee and many other foods) behave like catechol and are usefully superadditive with ascorbic acid. Would guess that many similar molecules exist in organic matter.
 
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