Lith developer formulation question

[grainyvision]

This is really great, and I will try to get this Polyethylene Glycol 3350 compound.

About this part B: it contains lots of Potassium Carbonate, and I wondered, whether you need that much to obtain strong buffering, or just to raise pH. If you just want to raise pH, then you might want to consider Trisodium Phosphate, which reaches higher pH than carbonates, but is more mundane than hydroxides.

PS: Many developers use Sodium Ascorbate or Sodium Isoascorbate and thereby avoid explicit addition of hydroxides or other strong alkalis.

The PEG-3350 is often used as a 100% pure over the counter laxative. Unsure of the brand names internationally, but in the US it's called MiraLAX. In theory any PEG of molecular weight between 1000 and 4000 should give similar improvements to contrast though

I needed the carbonate to raise pH or rather to neutralize the boric acid and ascorbic acid, but also I think I was aiming for the wrong set of balance. The formula had a working solution pH of 11.5-12, which is quite high for such a dilute lith developer. Boric acid seems a quite potent acidic buffer and it takes quite a bit of carbonate to break it. I actually have used TSP before but it's an extremely painful thing to use. Not very soluble and my bottle of it turned into a brick due to absorbed water.

The big reason to use ascorbic acid is it's more stable as a powder and in solution (of course, that doesn't apply if neutralized to ascorbate), more easily available, and part A needs to be at least mildly acidic either way for stability of the hydroquinone.

So I tried a new prototype. Kinda messed up in mixing it (doubled the water+glycol), but this is the intended formula:

• Start with 100ml of hot distilled water (distilled water is absolutely necessary here!)
• 2ml triethanolamine 99% grade
• 0.2g salicylic acid
• 15g ascorbic acid
• 8g sodium sulfite
• 13g hydroquinone
• Top to 200ml with hot propylene glycol

I was planning on bringing up pH with a hydroxide solution as needed, but the pH was actually at ~pH 6 when I tested it which is close enough. The TEA and sulfite I guess goes quite a way toward neutralizing the ascorbic acid when boric acid isn't a concern. I used the equivalent of the following with this:

* 500ml
* 10ml part A
* 9g potassium carbonate
* 0.3g potassium bromide
* 0.5ml 1% PEG-3350

The results were very slow, though that's somewhat expected at this dilution. pH was adjusted to a proper value at about 11 when fresh and maybe a bit higher than 10.5 when used for 1 hour. Solution only weakly discolored to the typical ascorbic acid orange (rather than hydroquinone yellow) after 1 hour in the tray. No hydroquinone byproduct film formed on top of the developer after 1 hour. Ilford MGV RC could not reach proper dmax and due to very long dev time (20m) ended up having fog. Ilford ART 300 FB did develop well but also slowly. Very subtle mottling (seems typical of lith) in black tones. dmax was ok but not stellar. Tones were a subtle warm brown, and brown blacks. Notably, the previous formula could not produce good results on ART 300, it'd have a strong mottling affect that obscured detail. This may indicate that either borate, TEA or higher pH could have caused some of the difficulties in the previous formula on certain papers.

Recommendations: use less PEG, maybe 0.2ml. Slightly reduce bromide used, maybe 0.2g, add very small amount of BZT to keep fog down without affecting lith effect. Consider if reducing sulfite amount is required.

edit: Also notable is that the ART 300 developed almost exactly like Ilford Warmtone FB. Specifically it seemed to never "take off" in the lith developer, but darkened substantially when placed into the fixer. I'm personally not a fan of this effect and consider the results to be sub-par compared to the more typical "true" lith effect. Result was over developed as a result, but with no fog. iirc dev time was 10m

 

[Rudeofus]

I needed the carbonate to raise pH or rather to neutralize the boric acid and ascorbic acid, but also I think I was aiming for the wrong set of balance. The formula had a working solution pH of 11.5-12, which is quite high for such a dilute lith developer. Boric acid seems a quite potent acidic buffer and it takes quite a bit of carbonate to break it. I actually have used TSP before but it's an extremely painful thing to use. Not very soluble and my bottle of it turned into a brick due to absorbed water.

A solution at pH 12 is not all that dilute! It really depends on the alkali you use. A pH of 12 means 10-2 mol/liter of OH- ions, you can get these with with about half a gram of Potassium Hydroxide per liter of water!
The problem you encountered with carbonate comes from the fact, that sodium carbonate sort of maxes out at pH 11-12, i.e. even if you increase concentration yet more, pH won't rise. If you need pH 12, then you have to use Trisodium Phosphate.

I do not really understand, what would be so painful about TSP: did you stir it with your hands??? Yes, it dissolves slowly, but it is very soluble at higher temperatures, wikipedia says "145 g/l @ 25°C, 233 g/l @ 40°C, 946 g/l @ 100°C", and that's the anhydrous, so imagine how much dodecahydrate you can sneak into 1 liter of hot tap water.

 

[grainyvision]

I was getting pH 12 with just 30ml of both parts added to 1L of water. The concentrate is just really concentrated. But again, I do think that this is actually the wrong kind of design to have. High pH introduces numerous problems, including unstable development, short tray life, and generally a bit more dangerous to work with.

Very weird. The TSP I have was extremely reluctant to dissolve. In one prototype I used 0.5g in 100ml of hot water and it took several minutes with a hot plate to dissolve. Maybe I had added carbonate or hydroxide beforehand and decreased the solubility. Either way it's a lot harder to get than carbonate in my experience, will turn into a brick very easily, and relatively expensive. Being a food additive I had assumed it'd be easy to get but TSP specifically is hard. disodium phosphate and sodium phosphate are much easier to get, but also useless here

 

[grainyvision]

An interesting observation for some mild EasyLith reverse engineering. The part A contains very little sulfite. Specifically, minimal sulfur dioxide odor detected upon adding acid. Part B seems to contain the primary amount of sulfite and definitely will wake your nose up when you break through the carbonate to neutralize it. When adding just a small amount of citric acid, part B also clears up from yellow to clear. I'm super curious what this yellow component is. I was surprised to find my part A is actually colorless. Unsure if it's gone off or if it was always like that. It does not match neither MSDS nor product photos. Regardless, found a wild paper about gold and sulfite complexes and thought that might be the special ingredient, but acidification should've made that obvious (though it would've meant the high price was justified!)

Regardless, I'm unsure if it's actually possible, but maybe ascorbic acid alone or nearly alone is enough to preserve the hydroquinone in acidic part A? If this is true then I can move the sulfite to alkali part B where it won't turn into sulfur dioxide upon storing. I still have doubts that ascorbic acid is actually capable of that, but maybe. How much ascorbic/ascorbate could I conceivably add if it in theory has minimal photo effects?

For my formula posted above, I'm unsure I actually need 50% carbonate as the part B (ie, to make it so equal ratios create something well performing), but it doesn't seem to be doing any harm other than to the overall cost. A bromide amount of 0.15g per 10ml of part A concentrate seems to be about right. This wasn't enough to slow things down, but was enough to even out development mostly. The sulfite amount used in part A seems to be too much. New is 8g and old was 5g. I think even 5g might be too much without a higher working pH which means TSP or hydroxide.

 

[Rudeofus]

I was getting pH 12 with just 30ml of both parts added to 1L of water. The concentrate is just really concentrated. But again, I do think that this is actually the wrong kind of design to have. High pH introduces numerous problems, including unstable development, short tray life, and generally a bit more dangerous to work with.

AFAIK most lith developers are very alkaline. The reaction runs roughly as Na2SO3 + H2O + HCHO <===> HCHO*SO2 + 2 Na+ + 2OH-, so the mix is a lot more alkaline than some may expect. The lack of primary development agents seems to make very high pH inevitable to force the Hydroquinone into action.

Very weird. The TSP I have was extremely reluctant to dissolve. In one prototype I used 0.5g in 100ml of hot water and it took several minutes with a hot plate to dissolve. Maybe I had added carbonate or hydroxide beforehand and decreased the solubility. Either way it's a lot harder to get than carbonate in my experience, will turn into a brick very easily, and relatively expensive. Being a food additive I had assumed it'd be easy to get but TSP specifically is hard. disodium phosphate and sodium phosphate are much easier to get, but also useless here

This is extremely weird. TSP does not dissolve as quickly as Sodium Carbonate or Sodium Hydroxide, but 0.5 g/l in 100 ml should dissolve quickly, especially in hot water. I have used both TSP anhydride and dodecahydrate - both dissolve moderately fast. If your liquid was already saturated with alkali carbonate, then there is a good chance, that the high amount of already available Na+ lowers the amount of TSP soluble, that's how pKsp works.

 

[grainyvision]

AFAIK most lith developers are very alkaline. The reaction runs roughly as Na2SO3 + H2O + HCHO <===> HCHO*SO2 + 2 Na+ + 2OH-, so the mix is a lot more alkaline than some may expect. The lack of primary development agents seems to make very high pH inevitable to force the Hydroquinone into action.

This is extremely weird. TSP does not dissolve as quickly as Sodium Carbonate or Sodium Hydroxide, but 0.5 g/l in 100 ml should dissolve quickly, especially in hot water. I have used both TSP anhydride and dodecahydrate - both dissolve moderately fast. If your liquid was already saturated with alkali carbonate, then there is a good chance, that the high amount of already available Na+ lowers the amount of TSP soluble, that's how pKsp works.

The real key with is that the true developing agent that makes it actually usable is very unstable hydroquinone radicals. Hydroquinone itself does not really become active at all until 10, and it's activity is too slow at 10 to really be usable (though some papers do indicate a lith developer at pH 9.25 is apparently possible). 10.5 seems to be the real minimum here, for typical lithable materials. For non-lithable it seems that pH is not really a factor so much as the amount of sulfite under pH 12. Too much sulfite and you'll get very weak dmax. If the pH is 12 or above though, then dmax is much richer even with relatively high concentrations of sulfite, but then you start getting other problems. I might order a fresh batch of TSP. Again, mine is turned into a brick so maybe mine has decayed into something less soluble or something.

 

[grainyvision]

So this EasyLith thing has continued to puzzle me and I stumbled on an interesting paper about how ascorbic acid oxidizes... One interesting component that could be the secret non-toxic agent of EasyLith could be reduced glutathione. The basic theory in such a case would be:

* Part A is mixed with both ascorbic acid and glutathione
* Part A absorbs oxygen, the ascorbic acid is converted to non-radical dehydroascorbic acid. Note that if too much oxygen is absorbed quickly though, the dehydroascorbic acid could further oxidized into non-reversible products
* glutathione reacts with dehydroascorbic acid to reform ascorbic acid
* glutathione is oxidized as a result and now inactive

This mechanism would only be possible and stable at the pH selected, ~5. Specifically, at a higher pH both the glutathione and ascorbic acid becomes rapidly less stable and though the glutathione would reduce oxidized ascorbic acid back, it'd quickly be consumed completely. Below pH 5, glutathione does not effectively reduce dehydroascorbic acid back to ascorbic acid. Note that at pH 5.5 this process is noted to be quite slow, several hours. Since you're not adding oxidizers to the solution though, this basically makes it a "slow" preservative. Along with providing for a potentially great method of extending shelf life, it also could allow for a "standardized" amount of ascorbic acid to be relied upon in the working solution. Specifically, when the pH is spiked by mixing part A with part B, the glutathione very quickly (within less than 1 minute) reacts with all of the dehydroascorbic acid, converting it to ascorbic acid. The only real question, is if glutathione itself is actually photo-inactive.

Either way, from a consumer standpoint high quality glutathione is extremely expensive (though easily available as a supplement), at least in the amounts I would see this needing and solubility limits are unknown. Glutathione specifically will reduce the dehydroascorbic acid with an efficiency of around 60% in a closed bottle situation (ie, not constantly adding oxygen), so it's not that efficient. The ultimate way to better restore this would be a reaction with sulfide, but that's of course a non-ideal thing to include or generate in a developer.

Anyway, just a Friday night half drunken rant about this curiosity.

edit: further note, that glutathione is not a magic chemical that could be used in any ascorbate developer. It only could potentially work toward this purpose as a secondary non-sulfite preservative in acid, ie, a 2 part developer solution

 

[Rudeofus]

The one thing, which strikes me about Glutathione is the -SH group. There are such compounds, which are strong silver solvents (e.g. Cysteine), most others are powerful restrainers (think PMT). Whatever this Glutathione does with Oxygen or Dehydroascorbic Acid, it will likely do a lot more to any Silver ion it ever encounters.

If you look in patent literature, most compounds for "protecting the ascorbate ion" are sequestering agents, which keep iron and copper at bay.

 

[Rudeofus]

About developer pH: Hydroquinone has pKa1 = 9.8 and pKa2 = 11.5. The most active form of Hydroquinone is the twice deprotonated form, which is predominant above pH 11.5. Above pH 12 you will not see much of an increase in developer activity.

 

[grainyvision]

First, for glutathione, there is a thread on here actually where someone tried using glutathione in place of ascorbic acid as a film developer. The negatives produced were very thin, but without any fog. The PMT part is very likely playing a part with that, but I imagine that glutathione could potentially be used as a "super-additive" regenerator for ascorbic acid. Regardless, less interesting for my lith pruposes.

Finally, so I've tried a lot to formulate a "modernlith" variant using only carbonate with no hydroxide, I've determined that if ascorbic acid is used, then it is impossible however. I'm unsure of the exact mechanism that ascorbic acid plays here, but it seems to prevent infectious development even if pH is highly buffered and kept at 11 using potassium carbonate. The shelf life is of course unknown, but tray life is exceptional. In a trial, it lasted 4 hours with minimal discoloration to yellow. No red or orange film or color develops. However, it's impossible to get modern papers to enter infectious development using this. It is seemingly possible to get lithable papers to enter infectious development with very good results though. Exact balancing is still very much TBD, but this would be a great base to build off of if you only care about lithable papers and not "modern" papers.

Formulas used:

Part A:
* 100ml hot distilled water
* 2ml TEA 99%
* 0.2g salicylic acid
* 15g ascorbic acid
* 0.5g sodium sulfite (note: not recommended, sulfur dioxide release)
* 13g hydroquinone
* top to 200ml with propylene glycol
* Add 0.5g baking soda to bring pH up slightly

Ad hoc part B:

* 150ml water
* 2.5g sodium ascorbate (actually iso-ascorbate)
* 50g potassium carbonate
* 0.5g sulfite
* top to 200ml with water

Usage path, tested on Ilford MGV RC:
* Add 25ml part A and 50ml part B to make 800ml working solution
* Add 0.25ml of PEG-3350 1% solution
* Add 2ml bromide 10%
Results: slow to develop, good contrast relatively speaking, but black tones are not deep at all, thus a low contrast appearance.
* Add 10ml hydroxide 10%
* Results: Slightly improvement in speed, black tones are still not really deep at all. A sheet of Fomatone Classic FB was tried (lithable). Very good results, with great contrast and deep but warm blacks, no noticeable problems
* Add 10ml hydroxide 10%
* Measured pH ~12.5
* Results: Way too fast and active. Gave some minor pepper spots. Development in center is noticeably uneven. Black tones are extremely black, contrast is somewhat reduced though because highlights tend to run away
* Add 4ml potassium bromide
* Add 0.4ml PEG-3350 1%
* Add 1ml of sodium sulfite 20%
* Results: Usable, but still too active and center development is lacking. Contrast is somehwat improved with more controllable development, blacks are still deep but slightly warmer. Still non-ideal highlight development
* Add 250ml of water
* Results: Usable, but center development still lacking. Blacks are deep and contrast is fairly nice and controllable without highlights running away much. Infectious development proceeds very quickly as blacks literally run across shadows

Note: The ascorbate is used in part B to act as a sacrificial anti-oxidant. I don't care about the ascorbate actually being there, but it hopefully will consume as much oxygen as possible rather than the sulfite doing that.

edit: too lazy to do all the conversion to abide by the extremely small limits of photrio, but here is a imgur album of a few of the results: https://imgur.com/a/9VQGMza

 

[Rudeofus]

Have you tried to dilute the developer versions which turned out too active?

 

[grainyvision]

Have you tried to dilute the developer versions which turned out too active?

Yes, it works to an extent, but seems to come with compromises on tray life, which is pretty much expected for this anyway.

The center development issue is the real puzzling thing in most of these formulas, but dilution only reduces it and doesn't eliminate it completely. Without inventing new and weird agitation techniques, I'm unsure there's a method of fixing it.

 

[grainyvision]

After a lot more messing around with this, I still believe ascorbic acid is a good component for an alternative lith developer, but it's very difficult. On the plus side, you can tell that the ascorbic acid is decaying in a bottle because it'll bulge (decays into CO2)... but ultimately I can't seem to get any consistency out of these formulas I've tried. Again, they'd work well enough for lithable materials, but with "modernlith-only" materials, I can't get the balance to be exactly right.

I was flipping through an old notebook (fun fact, apparently I've completely filled a 200 page notebook with different formulas) and stumbled on the precursor to my original published modernlith formula. "EXJ1"

Formula is as so:

* 4ml of sulfite 20%
* 10ml of hydroquinone in propylene glycol 10%
* 1ml of potassium bromide 10%
* 60ml of "carbonate" (likely potassium carbonate 20% but could be sodium carbonate 15%)
* 250ml of oxalate solution (could be either 10% potassium or saturated sodium that is around 3%)

Notes are: "PERFECT" underlined, 8m30s development time (likely room temp) on Ilford Warmtone RC. 2 hour tray life but works for 3 with some problems (likely pepper fogging). Included in these notes is the results from before adding any oxalate. "not great contrast. decent infectious development. developer is pale yellow after one print". Adding 100ml of oxalate to this initial developer without remixing then gave: "some red film on developer (likely ~1 hour after initial mixing), softer highlights, same development time"

My main problem with this formula was the contrast part, which is likely solved by addition of PEG-3350, and the cost of potassium oxalate (and very poor solubility of sodium oxalate). However, something clicked in me when reading it. Why buy potassium oxalate when it can be synthesized in solution. Oxalic acid and potassium hydroxide are cheap enough, and the solubility limits won't matter in the working solution. However, oxalic acid only has a solubility of 9g/100ml. Potassium oxalate has a solubility of 30g/100ml. It really highly depends on what my solutions were at the time I wrote that formula. Using 250ml is a lot and makes me think that it is very likely the saturated sodium oxalate, which means it's not too difficult.

Anyway, the real question is why does oxalate do anything in this context. It seems it should be inert and overall isn't really used in any developer formulas other than some very old ferrous oxalate formulas. I've had previous experiences where oxalate reduces the pepperballing effect of difficult FB papers, such as Ilford MGFB as well.

It's too simple of a formula to not try, but the real question is how can the hydroquinone be preserved in such a formula. Is HQ relatively stable in non-sulfite containing acid solution? I'm considering more like a split of hydroquinone + oxalic acid in part A, and sulfite+bromide+PEG+carbonate+hydroxide in part B.

Oxalic acid is an active reducer as well and should in theory be capable of replacing sulfite in terms of an oxygen absorbing preservative, giving harmless byproducts... but I've not seen it actually used much toward that for dissolved oxygen in water.

 

[grainyvision]

I mixed the following formula, as a super simplified formula without fancy solvents etc. I was mainly curious if propylene glycol was actually causing some effect


Part A:

• 150ml water
• 4g oxalic acid
• 5g hydroquinone
• Top to 200ml with glycol or water

Part B:

• 150ml water
• 0.5g sodium hydroxide
• 40g potassium carbonate
• 1g potassium bromide
• 4g sodium sulfite
• Top to 200ml with water

Working solution: 50+50 to 1L

I'm immediately remembering why I moved to include ascorbate after messing with this for a session. The color of the prints are definitely a bit more lively, giving more color on all papers tested.. but it's very unstable and relatively slow. To increase speed and contrast, I added 1g of potassium carbonate and 0.2g sodium hydroxide to the working solution. To counteract the fast decay, 0.3g of sodium sulfite was added. This did speed it up quite a bit, but then it begins to decay very rapidly, with the infamous hydroquinone "red film" effect on the developer, and peppering on Ilford MGV. Compared to other formulas, this broke compatibility with Fomatone FB paper (snowballs), but made Fomatone RC paper quite beautiful with nice warm browns and olives, though a bit low in contrast (maybe developer had decayed too much). Notably, PEG-3350 actually decreased contrast here in a single end of life test, but more testing required to actually confirm that. My suspicion is that the developer was too far gone to make heads or tails of. The developer was visibly decaying after 45 minutes and seemed practically dead by 2 hours. Ilford RC paper started peppering after 45 minutes. Average development time was typically 10 to 18 minutes using room temp (~70F) developer. After the alkali addition, I had only minimal problems with uneven development

I'm still waiting on potassium hydroxide to come in the mail, but plan on trying to make a solution of potassium oxalate using it, and added that to this working solution, to equal approx 8g in solution to test if it really did give tray life benefits. I also want to test some stronger dilutions and more on this PEG-3350 weirdness. Maybe PEG-3350 only matters at relatively high pH, above 12? Or maybe it restrains ascorbic acid more than hydroquinone. Unsure really, but this feels like an almost archaic formula compared to what I've been doing, so I'm having to basically relearn this and test what I thought I knew when not including ascorbate in solution

 

[albada]

I mixed the following formula, as a super simplified formula without fancy solvents etc. I was mainly curious if propylene glycol was actually causing some effect (...)

The Mocon film-developer I created consists of a few chemicals dissolved in PG. I discovered that yes, PG affects the developer. (1) It interacts with Phenidone in a way that increases fog, and (2) it creates esters with borates enabling dissolution. So I think there's a chance it could affect your work, so you are prudent to be wary of PG.
Mark Overton

 

[grainyvision]

The Mocon film-developer I created consists of a few chemicals dissolved in PG. I discovered that yes, PG affects the developer. (1) It interacts with Phenidone in a way that increases fog, and (2) it creates esters with borates enabling dissolution. So I think there's a chance it could affect your work, so you are prudent to be wary of PG.
Mark Overton

Wow very interesting. I've had problems in the past where even a relatively low pH (around 9.5) PC developer gave a measurable amount of base fog. The way I got the phenidone into solution though was by mixing a 1% PG solution.

 

[grainyvision]

Regarding the lith formulation, I still have absolutely nothing to go on for the actual mechanism, but having a fairly large amount of potassium oxalate in solution will significantly extend tray life. My only guess is that oxalate will neutralize peroxides generated by hydroquinone, which may be what causes hydroquinone to self-oxidize. The effect is negligible unless using a fairly large amount. Seems like I'd expect 2.5 hours from ~1g of sulfite in solution using 1.2g of HQ and 6g carbonate+0.2g sodium hydroxide. PEG-3350 does give some benefit, but not as much as ascorbate containing formulas (PEG seems to prevent the ascorbate from acting as a developer in those, whereas here it acts differently in just an HQ formula)

Using the above prototype formula, I used the following addenda to be precise at a dilution of 50+50 to make 1L:

* 1ml sodium sulfite 20%
* 1ml potassium bromide 10%
* 1ml sodium hydroxide 10%
* 10ml potassium carbonate 20%
* 0.5ml PEG-3350 1%
* 50ml of oxalate solution

Oxalate solution was produced by doing the following:

* 50ml cold water (iced water preferable)
* 25g oxalic acid (will not dissolve. Note mine is not anhydrous, it has a wet appearance)
* 30g potassium hydroxide (DANGER! Extremely exothermic, add very slowly with constant stirring)
* Top to 100ml with water. Target pH: 6.5
* Strain through filter to remove brown spec impurities

With a further test using double the addenda and 100+100ml to make 1L, tray life was at least 4 hours (stopped using after 2.5, was still just a somewhat dark yellow. At 4 hours was a pale brown. Likely would continue to work a while longer). Beginning pH was 11 and ending pH was 11

Papers tested:

* Ilford MGV RC -- Very slow 18m, somewhat decreased contrast compared to typical formulas. Brown blacks and orange highlights
* Fomaspeed RC -- Fast 6m. Beautiful with proper contrast, slight tendency to give uneven development in center, and neutral to cool browns depending on solution age. Gives some grain
* Fomatone FB -- Incompatible, gave up after 30m. Was not improved by 100+100
* Ilford Warmtone FB -- Slow, 22m, somewhat typical results compared to other developers. Brown blacks that aren't too deep. 50+50 gave pepper balls, but 100+100 worked well enough
* Fomatone Classic FB -- Fast, 7m. Nice amount of contrast with deep blacks, subtle shadow gradation, and yellow/olive tone split. Only tested at 100+100
* Kodabrome RC (expired, lithable) -- Fast, 6m. Ok black depth, fairly neutral tone, somewhat grainy
* Ilford MGFB -- Incompatible, as with all previous attempts