It is believed that low levels of sulphite will add moderate speed increase, because the solvent action opens up buried exposure points; should this work for other silver solvents (Amounts too low to effect grain)?
Question for the chemists.
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Hi, I personally can't give any sensible answer to your question. But seeing as you seem new to photrio perhaps I can point you somewhere.
A well-respected forum member, now deceased, had a great deal of experimental knowledge, etc., related to chemical interactions with film emulsions, etc., during his time in the Kodak Research Labs. He went by the forum name "Photo engineer," or PE for short. It might be useful to search through some of his posts.
The forum search routine is not the greatest, but I would suggest starting with a search along the lines of: search for: "sulfite solvent" by: "photo engineer". (I tried it and got two pages of hits.) From there, maybe new leads appear. Best of luck!
Ps, fwiw it often seems that once a discussion gets started here, people seemingly appear out of the woodwork with obscure knowledge that one, me anyway, would never expect. So if you see any specific hints, etc., probably worth asking further.
A well-respected forum member, now deceased, had a great deal of experimental knowledge, etc., related to chemical interactions with film emulsions, etc., during his time in the Kodak Research Labs. He went by the forum name "Photo engineer," or PE for short. It might be useful to search through some of his posts.
The forum search routine is not the greatest, but I would suggest starting with a search along the lines of: search for: "sulfite solvent" by: "photo engineer". (I tried it and got two pages of hits.) From there, maybe new leads appear. Best of luck!
Ps, fwiw it often seems that once a discussion gets started here, people seemingly appear out of the woodwork with obscure knowledge that one, me anyway, would never expect. So if you see any specific hints, etc., probably worth asking further.
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This is the search result: https://www.photrio.com/forum/search/1498683/?q=sulfite+solvent&c[users]=Photo+Engineer&o=relevance
Alternatively, if you don't like the forum's own search, 3rd party tools like DuckDuckGo (or Google, if you must) can also crawl a specific site:
site:photrio.com "photo engineer" "sulfite" "solvent" at DuckDuckGo
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High dilution with high pH
Hello Someone experimented with very high diluted film developers, but with increased pH to 11-13?
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@Rudeofus also made posts about the ethanolamines IIRC.
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The rough theory behind sulfite as a speed improver is that it may expose latent image sites to development that would otherwise not be reachable by the developer.
Sulfite is "nice" in that it's quite a mild silver solvent.
Reversal first developers, which are concerned with developing as much of the exposed image as possible use other, stronger solvents. This may be one of the (many) reasons for the seeming speed increase in reversal. But first developers for reversal are also generally OK with removing a bit of the image. There might be a level of e.g. thiocyanate that provides a small boost but does not remove too much silver. I wonder if it would deliver any effect worth noting beyond that delivered by sulfite.
It should also be noted that sulfite does not universally improve speed. It depends on the developer chemistry involved. It may have to do with molecular size of of the active agents or other physical factors of the emulsion and expansion and pH.
Sulfite is "nice" in that it's quite a mild silver solvent.
Reversal first developers, which are concerned with developing as much of the exposed image as possible use other, stronger solvents. This may be one of the (many) reasons for the seeming speed increase in reversal. But first developers for reversal are also generally OK with removing a bit of the image. There might be a level of e.g. thiocyanate that provides a small boost but does not remove too much silver. I wonder if it would deliver any effect worth noting beyond that delivered by sulfite.
It should also be noted that sulfite does not universally improve speed. It depends on the developer chemistry involved. It may have to do with molecular size of of the active agents or other physical factors of the emulsion and expansion and pH.
Of note here: exposing other latent image sites by modifying the behavior of the gelatin has also been experimented with. Agfa used PEG in their Scala reversal first developer presumably in this capacity.
Thank you for the replies, I have done many searches, It was conversations between PE, Ian Grant, and Gerald Coch, that peaked my curiosity. I was just trying to get a few grams of sulfite into a PCTEA type developer, to boost shadow speed a little. My first idea didn't work, I have a few other options, but was wondering if a different solvent might achieve similar results. I know i could just add it to the working solutio, n, but I like futsing to keep busy sometimes, I could probably just get T-max to do the same result, but what's the fun in that.
Thank you, this implies it is at least plausible. when my film and chems get here I'll try.
If anybody is interested I'll post the process and results, unfortunately I have no way to scan right now, so I'll have to find some way to get pictures loaded.
If you're referring to adding sulfite to a PCTEA developer or boosting shadow speed, you might find a few posts here interesting:
www.photrio.com
www.photrio.com
Instant MYTOL
Here's a formula that gives a developer with the same ascorbate and phenidone concentrations as MYTOL, has a similar sulfite concentration, and matches the pH of MYTOL's stock solution. It should be simpler to mix in that it doesn't use sodium...
www.photrio.com
A very low contrast, low pH, full speed POTA variant
Initially I thought this might have been a small amount of Pyro stain, but I get the same results with all the test formulas, XTOL, etc., so I assume it to be a property of the film, which is why I didn't include these blue/green curves in subsequent plots. You do realize that it is mostly...
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It would be possible to replace some of the TEA in PC-TEA by DEA or MEA but:
[1] Heating such a mix is even more hazardous
[2] Although they are better silver halide solvents, when diluted with water the pH is raised compared to TEA so the grain might not be any finer.
[3] The freezing point , at least with DEA, is raised and the mixture may be solid at room temperature.
See this thread:https://www.photrio.com/forum/threads/xtol-patented.53418/page-2 [fig 6 gives pH].
[4] To get round the freezing problem it may be possible to add another low melting point solvent , see the sds for the syrup version of HC-110.
It seems like a complex and hazardous process to me, easier just to buy some Adox HC-110 syrup or Ilfotec HC.
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You have to remember that Glafkides was writing about materials that had quite buried iodide (and which were on the cusp of obsolescence at the time he was writing, never mind a decade or two later.
With that in mind, access to the emulsion both in terms of developable centres but also in terms of getting the emulsion to release development inhibiting agents (a really important area of research as it allowed for dramatic improvement of granularity and sharpness relative to emulsion speed - and better highlight density control) has been a key area of research interest for a long time - today emulsions are essentially built to maximise these properties (especially in treatments carried out and addenda used in the emulsion finishing stages to maximise the accessibility of the emulsion - e.g. the use of KSCN), and fundamental knowledge about structures and developer formulations can be more optimally intended to interact - for example, it is possible to build a reasonably fine grained but very sharp working developer that maximises emulsion speed - yet has significant safety margins - and the key ingredient is the use of a particular organic restrainer - and this is not some garden-shed formulated thing that stains negatives.
Another interesting aspect is the fairly arcane and not terrifically well publicised (it was commercially sensitive) work by Ilford and others that seems to have found shortcomings with the highly concentrated amine based formulations with emulsion structures common by the end of the 1980s - hence the shift back to aqueous formulations (as the other solutions seemed to involve potentially very costly organic synthesis).
With that in mind, access to the emulsion both in terms of developable centres but also in terms of getting the emulsion to release development inhibiting agents (a really important area of research as it allowed for dramatic improvement of granularity and sharpness relative to emulsion speed - and better highlight density control) has been a key area of research interest for a long time - today emulsions are essentially built to maximise these properties (especially in treatments carried out and addenda used in the emulsion finishing stages to maximise the accessibility of the emulsion - e.g. the use of KSCN), and fundamental knowledge about structures and developer formulations can be more optimally intended to interact - for example, it is possible to build a reasonably fine grained but very sharp working developer that maximises emulsion speed - yet has significant safety margins - and the key ingredient is the use of a particular organic restrainer - and this is not some garden-shed formulated thing that stains negatives.
Another interesting aspect is the fairly arcane and not terrifically well publicised (it was commercially sensitive) work by Ilford and others that seems to have found shortcomings with the highly concentrated amine based formulations with emulsion structures common by the end of the 1980s - hence the shift back to aqueous formulations (as the other solutions seemed to involve potentially very costly organic synthesis).
I'm not trying to make a fine grain developer, I'm just trying to add the equivalent of 5g per liter sulfite, to try to get a fraction of a stop more shadow speed; I may also try replacing some of the TEA with glycol to decrease the buffer capacity and possibly get some compensating effect. I truly don't want to work with DEA or MEA. My first attempt was to add sulfite to glycerin, and change the ratio from 1:50 to 1:25, not soluble enough; I could get enough metabisulfite dissolved, but not enough base to bring the PH back to where I wanted it; planed on just making a 2 part, looked around some more, saw where bromide was added to PCTEA by dissolving ammonium bromide than heating to remove the ammonia. considered this with ammonium sulfite; then considered adding a minute amount of ammonium chloride, as it's a strong silver solvent, to see if it has the same effect. I have a simple solution, this is just bullheadednes, and the fact that I enjoy designing things for no good reason. My other option is to add SO2 to TEA instead of DEA, but I would prefer to avoid this. I'd probably just use X-tol if I didn't work in spurts, and had a good place to store it, but for now I prefer to work one shot. I figured I could cut a roll of arista, to see if it added any speed or not, or possibly just fog; just wondered if it was even worth testing; I already have plenty of ammonium chloride, hey it's not just for licorice.
Thank you for the information, I just thought I would make my goals clearer. Right now, low hazard and toxicity are a primary goal.
Thank you for the information, I just thought I would make my goals clearer. Right now, low hazard and toxicity are a primary goal.
In response to your original question: MAYBE? But why? Sodium sulfite is cheap, common, and pretty well understood.
In the good old days, Bill Pierce was an advocate of Tri-X in Rodinal with sodium sulfite added. As I recall a half scoop from the spoon packaged with Chock Full of Nuts coffee.
And at one time, a well know developer, Edwal FG-7, recommended diluting their concentrate with 15% sodium sulfite solution rather than plain water for certain "classes" of films.
In the good old days, Bill Pierce was an advocate of Tri-X in Rodinal with sodium sulfite added. As I recall a half scoop from the spoon packaged with Chock Full of Nuts coffee.
And at one time, a well know developer, Edwal FG-7, recommended diluting their concentrate with 15% sodium sulfite solution rather than plain water for certain "classes" of films.
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Some people believe that PC-TEA loses a bit of speed due to the solvent effect of the TEA. Unlike sulfite, this solvent action is said to be detrimental to film speed. To increase speed, one might try a similar developer, such as PC=512, which uses glycol instead of TEA.
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If you're referring to adding sulfite to a PCTEA developer or boosting shadow speed, you might find a few posts here interesting:
Instant MYTOL
Here's a formula that gives a developer with the same ascorbate and phenidone concentrations as MYTOL, has a similar sulfite concentration, and matches the pH of MYTOL's stock solution. It should be simpler to mix in that it doesn't use sodium...A very low contrast, low pH, full speed POTA variant
Initially I thought this might have been a small amount of Pyro stain, but I get the same results with all the test formulas, XTOL, etc., so I assume it to be a property of the film, which is why I didn't include these blue/green curves in subsequent plots. You do realize that it is mostly...
I have found that Instant Mytol works well. Besides the sulfite, it differs from PC-TEA by having a lower pH, perhaps a higher concentration of developing agents and less base fog. One might think that Xtol developers always use an aqueous solvent. But Jordon formulated a version of Instant Mytol where part A was in glycol. If you add sulfite to PC-TEA, you are essentially moving in the direction of an Xtol type developer. So it might be easier to use an already formulated Xtol clone or FX-55. Gainer did say the sulfite could be added to PC-TEA, though he didn't see the sense of it.
You might get more useful effects from adjusting the P:C ratio.
Studional was essentially PQ-TEA. A little digging in the Agfa patent record etc might yield some useful information.
I did a fair bit of experimenting in this realm a few years ago and found that with a PC developer, ratio of agents has an effect on fogging and speed, that lower pH leads to smaller grain (as expected) and that borates seem to have some additional positive effect on grain irrespective of pH. Gelatin swelling may come into play here with regard to pH.
When the above is tuned, sulfite makes only a little difference in grain and is unnecessary to prevent fogging. But the tradeoff of adding sulfite is reduced sharpness. You don’t need it to reach box speed (or higher on some films).
The result of that work was PC-512 Borax mentioned above by @bluechromis . I had tried some experimentation with a single concentrate, replacing some of the glycol with TEA instead of using borax. But it was less promising in terms of grain structure and speed. If you work in that direction, I’d be interested to see your results.
When the above is tuned, sulfite makes only a little difference in grain and is unnecessary to prevent fogging. But the tradeoff of adding sulfite is reduced sharpness. You don’t need it to reach box speed (or higher on some films).
The result of that work was PC-512 Borax mentioned above by @bluechromis . I had tried some experimentation with a single concentrate, replacing some of the glycol with TEA instead of using borax. But it was less promising in terms of grain structure and speed. If you work in that direction, I’d be interested to see your results.
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