"EXA6", a custom lith developer formula capable of creating lith prints on most modern papers

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grainyvision

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So I love lith printing, but the constantly shrinking availability of lith capable papers has really been bumming me out. I've been chasing methods of lith printing on Ilford RC papers specifically, since they are generally the hardest ones to tame but also clearly will be available for a very long time to come. From early on I was able to get the paper to lith with careful developer formulation, but it always had quite severe problems that made it impractical for realistic usage. The primary problems being too much paper grain and uneven development. I was doing some research one night and decided to try adding a small amount of Glycin to the developer. This completely opened up the highlights and midtones compared to an HQ only developer with these difficult papers, imparted a lot of new color, and finally mostly solved the uneven development problem (along with carefully random agitation of course).

I wrote a blog post about the developer formula that you can see here: https://grainy.vision/blog/exa6-magic-lith-reference .. However, I'll also copy-paste the post to here for easier reading. You can see higher resolution images and such at my blog though.

EXA6 "Color Magic Lith v1" Reference
December 15, 2019


This is finally what I’d consider a “successful” developer. It’s definitely still capable of plenty of tweaking, but finally, this is a good base to build on. It exhibits the following properties:

  • Will create traditional looking lith prints on most papers, including otherwise unlithable RC papers. Successful tests so far include Ilford MGV RC, Ilford Cooltone RC, Ilford Cooltone FB , Kodabrome II F3 RC, Fomatone 133. Unsuccessful tests include Adox MC112. Recommended especially for Ilford papers

  • Produces a relatively fine-grain lith print with some papers which are normally quite grainy (though others may exhibit additional grain and perform like a coldtone paper with less coloration)

  • Exhibits a rich split tone spectrum of color on at least some papers. For MGV for instance, it yields subtle golden extreme highlights, delicate peachy highlights/high midtones, olive green midtones, and somewhat cool shadows.

  • Follows the 2nd golden rule of a lith developer, though not the first. Grain size and color is difficult to adjust through dilution, but the 2nd rule for more exposure = less contrast holds up. It is possible to get deep blacks with anywhere from 1-5 stops of over exposure from a base print while the highlights can be controlled completely by exposure rather than by development time.

  • Different development times (and thus contrast levels) appears to be somewhat capable of modifying color/grain size, with more color being introduced with longer development times

  • Workable tray life, extremely shelf stable. The tray life with this developer isn’t exactly great, but in my testing it only starts to really fall off after 1 hour, which is plenty workable for several prints. The shelf-stability of the solutions should be years due to the developing agents being kept in a solution without water
I plan to later release an updated version of this formula so that it is only a 3 part formula, rather than the current 6, but all of the components listed here are useful on their own for advanced lith printers so it’s expected that not all people would prefer an “all in one” solution.

EXA6 Formula
  • 15ml HQ-TEA 20%

  • 10ml Glycin-TEA 6%

  • 15ml Sodium Sulfite 10%

  • 50ml Benzotriazine 1%

  • 1ml Potassium Bromide 10%

  • Top to 2L with water

  • 20ml Potassium Carbonate 30% — add just before ready to begin printing
Direction for use:

  • This developer can be used as a standard lith developer with some additional cautions especially with difficult papers.

  • Agitation should be very random and inconsistent. ie, swirl the print, rock the tray, etc.. basically ensure everything gets an even amount of developer. Using a larger amount of developer than needed and a larger tray also helps. With some papers it is nearly impossible to get 100% even development, but there are some formula modifications to improve this, and it of course helps to choose a negative to print where this unevenness doesn’t matter too much.

  • As this developer is used a red film will appear in the solution. This typically becomes apparent after 2 or 3 prints. The red film is oxidized hydroquinone. It won’t hurt anything but should serve as an indicator of the developers state. When this film is rather obvious and thick on the solution, it may be time to replace the developer. Additional sulfite can be added to remove this film and potentially even revive the developer, but sulfite seems to react non-intuitively here and it seems if there is no red film coming up at all, the developer probably has too much sulfite and won’t give proper infectious development.

  • In order to mix the formula, it is easiest to use a small (100ml) graduate to measure out the TEA mixtures and then add the sulfite and other components (excluding carbonate) on top of that. Then instead of just dumping it into a tray of water, fill the small graduate from the sink with water and dump it into a larger graduate (1L) for measuring the final developer solution, effectively rinsing the TEA from the small graduate several times in order to get it all out. The carbonate should be added at the very end after dilution. If added early it can quickly kill the developer.

  • With difficult papers the times can be quite slow. Induction times of 5m with room temp developer is pretty normal for Ilford MGV. To speed things up the developer can be heated, but this will reduce the tray life of the solution

  • With MGV (and probably most others) you will first see the border of the print as is typical in lith printing. Afterwards the blacks will slowly start to become visible. Finally midtones and highlights begin to come up across the print, with blacks appearing to stall. Suddenly, the blacks go infectious and a deep black tending to have more infectious development at edges. In most cases the blacks will begin to really come in just as the highlights are almost completely developed. The print may have uneven blacks, but you can keep it in the developer for quite a long time before midtones and highlights get any darker than at this point.
Mixing the TEA (triethanolamine) compounds:

These are annoying at best. The HQ-TEA must be heated to at least 160F, with 180F making things a lot easier. I use a hot plate and glassware to accomplish this. I’ve heard of people microwaving TEA, but this seems overly dangerous to me. If the TEA is hot enough, the HQ will appear to melt into the solution and become a slime before dissolving. Note that the volume will inflate considerably, so to make a 20% solution, I’d recommend something like 400ml TEA + 100g of HQ and then after it is dissolved top up the solution to 500ml with more TEA. This solution is extremely resistant to oxidation and only needs to be kept in a closed bottle with no other special precautions. It will appear a pale reddish orange when completely mixed.

The TEA-Glycin mixture is more stubborn to mix. According to other people online, glycin is capable of going to at least a 10% solution in TEA. However, I could not achieve this. I highly recommend investing in a magnetic stirrer unless you really want an arm workout. In my testing a 6% solution took around 50 minutes of stirring to fully dissolve while heated at 200F. I think heating is not as necessary here, but the very long stirring time is. This mixture will be a slightly darker brown color compared to HQ-TEA. It should also keep in theory almost indefinitely with no special precautions other than to keep water out of it. The glycin I used was fairly fresh and a light tan color, unknown what the result of fresher or older glycin is.

Ingredient Considerations
  • A high amount of HQ is required. I wouldn’t recommend decreasing the amount of HQ used here, but increasing it might give interesting results. Without a fairly large surplus of HQ, infectious development just will not happen with difficult papers. It might give good results on true lithable papers though.

  • Glycin behaves quite peculiar in this formula. Glycin is reported to be super-additive with HQ, but I do not see that effect really here and it seems to behave in a completely different way. It is a bit of a mystery the exact effect behind it, but end result of glycin addition is a decrease in grain, better separation of midtones (without which tends to go to black too quickly), significantly more even development of highlights and midtones, and a ~20-50% increase in overall development speed. Glycin is technically optional, but controlling this developer without it on difficult papers is otherwise impossible as midtones will quickly go to black and uneven development will be very obvious with the center being significantly less developed than the edges.

  • A rather low amount of sulfite should be used to get good infectious blacks. With too much sulfite, the blacks will merely be a dark grey rather than colder black. More sulfite can be added per print as the sulfite is used up, but this is very hard to judge with any real consistency. Additional sulfite will cause infectious blacks to come up slower. Too little sulfite though and the developer dies before the first print is done. I’d recommend at least 5ml of 10% solution and no more than 25ml. Normally formaldehyde would be used instead of actual sulfite. However, formaldehyde also tends to harden emulsions and thus I suspect it will not produce a universal lith developer. This is my hunch, but I don’t expect to ever work with it personally. It’s also carcinogenic and not a chemical I’d like to design a developer around because of that.

  • A high amount of benzotriazole should be used. The benzotriazole effectively will decrease the speed of development in every way except for after infectious development occurs. By using a high amount, it is capable of making highlights and midtones develop significantly slower than blacks. Some particularly stubborn papers may benefit from increasing this to up to 100ml, though this will also greatly increase development time and probably will give some differences in contrast. Note that benzotriazole content of the developer will decrease with each print. This shouldn’t matter too much over the short working life unless attempting to replenish the developer.

  • A low amount of bromide should be used. Bromide especially slows down infectious development with difficult papers and thus should be used quite sparingly. It can be increased if your goal is to not have true cold blacks, but otherwise I see no reason to modify the current minimal amount. Many documents say that some halide of some sort is necessary for infectious development to take place, but I’d consider this really to be an optional ingredient since the paper contains bromide anyway. The developer will naturally produce slightly warmer and greener blacks as more paper is developed either way due to bromide released from the paper.

  • Potassium Carbonate. This can almost surely be substituted with Sodium Carbonate but potassium is just what I had on hand. The carbonate is used to get the pH to around 10.5. A higher pH (ie, more carbonate) can be used for faster development times and overall colder tones, but this may need to be balanced with more benzotriazole otherwise highlights and midtones may develop too quickly. More carbonate also will reduce the tray life of the developer. Less could probably be used as well, but the pH should always be kept above 10 for infectious development to happen properly. Less carbonate will also cause development times to increase significantly.

  • Dilution has not been experimented with much, but I expect this formula is already close to the maximum dilution for good blacks.
Paper Results
Finally, I’ll describe the results of the different papers tested. Some slight modifications to the formula were made as these tests were done, but nothing exactly groundbreaking. A portfolio of scans from this process is below if you just want to skip to see the results for yourself.

  • Ilford MGV RC — This is the paper was used primarily to guide this developer formula and so is the most well suited for this. This provides a full spectrum of colors going from golden to peach to olive to cool blacks. This paper is “difficult” in terms of uneven development, but easily possible with enough persistence in perfecting a good and random agitation technique. The development process can be a bit weird coming from traditional lith printing. At room temp, the initial blacks come up around 5 minutes., then the blacks seem to stall while the highlights and midtones fill in, about 8-12 minutes depending on exposure. Finally right as the midtones really start to look right the blacks take off and the highlight and midtone development seems to stall. Total snatch time typically from 15-25 minutes, can be sped up with heated developer. Note that the glossy finish can sometimes exhibit weird grainy line effects due to the way the glossy coating is put onto the paper. Pearl does not exhibit this effect. Color stays pretty much the same between dry and wet.

  • Ilford Cooltone RC — This paper is workable, but not exactly exciting. Blacks are more sluggish than MGV and overall will not develop to as dark. Color spectrum is from lilac to cool greys and blacks. Contrast is typically less intense than MGV. Color will become even more subtle when dry.

  • Ilford Cooltone FB — This behaves completely different from the RC version. Blacks are significantly more intense, and the color spectrum resembles that of MGV (peach, olive, cool black), but a bit more subtle and with overall more interesting shadow gradation.

  • Kodabrome II F3 — This is a lith printable paper that I often use with normal lith printing. It does work here, but is definitely not anything exciting. Normally the color spectrum is peach highlights and cool shadows. However, in this developer it doesn’t produce great blacks and the color spectrum changes to lilac highlights, somewhat golden midtones, and somewhat cool shadows. It also is normally a fairly fine grain paper, but in this process becomes rather grainy. Color will become somewhat more subtle and golden when dry

  • Adox MC112 FB — This paper was the first failure in this. I believe more benzotriazole could potentially solve it, but haven’t had time to test it. With this highlights and midtones will develop only somewhat slower than the blacks. The blacks will also spread across the image from the edges, making it very difficult to get good shadow gradation. Color spectrum was yellow to mostly neutral and cool. The results here are quite striking, but not something I’d say can be used for all or even most subjects because of how unevenly it develops.

  • Fomatone 133 FB — This paper gave rather striking results. This test isn’t exactly reliable. The developer was nearly dead because a kid’s nosebleed interrupted a session forcing me to leave the developer after 1 print for 30 minutes. It developed a lot slower, but gave great results when it finally got to where I wanted. Blacks were somewhat cool and not greatly intense, but the shadows were a beautiful deep brown, and with peach highlights and sepia-ish midtones. In normal lith printing I’ve only gotten peach and olive colors, as well as having weird problems with blacks “spreading” from the edges and darkening highlights. In this process the paper worked perfectly though similar to MGV.
Results
Note that all tests here were scanned and then carefully color corrected to best match the appearance of the print in daylight conditions.

(see attachments)

Conclusion
This developer should prove to be a very promising and useful tool available to expert lith developers. The glycin requirement of the developer is really the most difficult part, as it is only available from one manufacturer, keeps poorly as a powder, and does not mix very easily into TEA. Otherwise all chemicals used are stable and often stocked by people capable of mixing their own developers. I intend to eventually test using metol instead of glycin, but do not expect much success since metol is a much more active developing agent and doesn’t have glycin’s reputation for “glowing” highlights and midtone separation. This developer and minor modifications to it will continue to be used for my personal lith printing with occasional updates on especially nice prints made in it… but for now, this idea is “complete” and requires no further discussion. I’d definitely appreciate any reports of other people trying this process out, especially with papers not listed here or even old expired papers I don’t have easy access to. I’ll do a “guest” post featuring other people’s images (with permission) of this process if I can collect some examples of it being used outside of myself. I’m also interested in a way of using the HQ-TEA and Glycin-TEA mixtures in other developer formulas beyond lith printing. I also do plan on trying some other lith printing formula ideas, but for now this satisfies me. I will put up some more experiment reports later on with the result of this developer with various papers and various toning techniques.
 

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grainyvision

grainyvision

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I found a very interesting patent that might help to explain some of this, though it in itself contains very little explanation. The patent number is US 4172728, http://www.freepatentsonline.com/4172728.pdf

Basically the formula they give is quite similar in theory to EXA6 with the following modifications (along with generally being much more concentrated of course, being for true lith applications):

* substantial amount of sulfite used (45g per liter)
* 100:1 ration of hydroquinone:tongue:henidone (15g:0.15g per liter) (note that it says other secondary developing agents can be used, but that phenidone is the best)
* emphasizes that an amine (such as triethanolamine) must be used for pH balancing purposes, with substantially worse results when using hydroxide instead
* Recommends a different but similar antifoggant than benzotriazole, in similarly somewhat substantial amounts (0.3g / liter, 30ml of 1% solution)
* Includes ethlyn glycol (though not described as essential in anyway.. maybe as a surfacant?)
* Includes a fairly large amount of bromide compared to EXA6 (though not described as essential)

Similarities:
* Uses a secondary superadditive developing agent in small amounts
* Uses a relatively large amount of hydroquinone
* Contains a measurable amount of TEA (contains results for TEA, but most examples use the higher pH DEA)
* Uses a fairly large amount of antifoggant

It seems that the secondary development agent, triethanolamine, and antifoggant are all absolutely essential.. however, it gives no real info about the relatively large amount of sulfite. The patent is for a rapid-access (ie, fast processing and long lasting) lith developer, so this amount of sulfite would be needed I suppose so that the developer can stay alive for longer than an hour at high temperatures. However, with this amount of sulfite in a normal lith developer infectious development would definitely not occur. The results would be similar to the published ones using hydroxide I assume.. so the TEA is really one of the big "wtf" components that I'm trying to wrap my head around. I found some interesting (non-photography) references that TEA actually will absorb sulfur dioxide.. ie, TEA will basically absorb what sulfite becomes in solution. However, does it then release that somehow? Does HQ or its oxidation products react with the TEA-sulfur product directly somehow? Maybe TEA acts as a stronger "container" for sulfur here and won't let highly reactive quinone steal it, but also still allows for scavenges oxygen/preservation for HQ itself?

The secondary developing agent is also a mystery. Phenidone specifically will develop a silver grain and oxidize, then HQ will come in and oxidize and restore the phenidone. I can't find any documentation to what the HQ will oxidize to, but if it oxidizes to the highly active quinone... and since phenidone attaches to the grain (ie, this happens locally at the grain, not overall in solution), this quinone product then can immediately hit a surrounding silver grain and thus cause infectious development. That's just a working theory, but I suspect this may be why EXA6 containing glycin causes such an increase in even development. The patent does not go into any real detail or results of how the formula behaves without the secondary developing agent.

I've done test runs where I make EXA6 without the glycin and then add it in afterwards. The results before adding glycin is extremely eager infectious development, but that is not well spread, extremely uneven. Despite developing 4 prints, I also saw no change in color of the developer nor distinct red film... ie, the hydroquinone isn't really oxidizing as fast. After adding glycin nothing really happens for several minutes at least. But the first print afterwards has a much slower induction period (ie, some midtones and highlights come in before infectious development starts) and behaves slower overall, almost as if glycin is a restrainer of sorts here. The development as stated is of course significantly more even and natural too. After that first print though, the color was instantly changed to yellow, and after another print the characteristic red film formed. I found that I can get a good number of prints even after the developer is a deep brown, but blacks won't come in properly, I assume due to not enough HQ left in solution

Just when I think I'm done with research on this, I find an interesting patent that seems like a potentially great set of leads to improve this developer significantly. Primary improvements wanted:

* Better blacks with most papers (some papers already give really strong blacks, but several do not, including some normally lithable papers)
* Slower midtone development compared to current shadow development speed (highlights already develop slowly enough, but midtones have a tendency to run to black with higher contrast/less exposure)
* Better tray life (really only 2 prints can be made from 2L currently. After that the blacks will be visibly weaker with all papers)
* Remove glycin. Glycin is fun, but it's a real pain. The powder keeps very poorly, and it is quite reluctant to dissolve into TEA compared to HQ
 

koraks

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I'm following this with interest. At rhe same time, I wonder if your approach needs to be as complex as it is. I've messed around a bit with formulas based on Riuyi Suzuki; very simple, 3-component formulas (2 for the concentrate if you leave out the bromide and add it later - or a chloride instead). I found I could tailer the developer to just about any paper I tried using just dilution, the ratio between developer and activator (sometimes using hydroxide is teas of carbonate although just carbonate suffices most of the time) and shift the colors to yellow, orange and maroon using plain old sodium chloride in rather high concentrations. A two-bath approach à la Moersch Polychrome using a slow metol developer worked fairly well too, although here, glycin would probably have helped boost colors. But I don't happen to have any, so I didn't try.
So instead of making the chemistry more complex, I tried to keep things as simple and flexible as possible, which seemed to work quite well. Granted, I didn't bother with RC papers because their uneven coating (mottling) tends to become a problem in lith applications one way or another.
 
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grainyvision

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I'm following this with interest. At rhe same time, I wonder if your approach needs to be as complex as it is. I've messed around a bit with formulas based on Riuyi Suzuki; very simple, 3-component formulas (2 for the concentrate if you leave out the bromide and add it later - or a chloride instead). I found I could tailer the developer to just about any paper I tried using just dilution, the ratio between developer and activator (sometimes using hydroxide is teas of carbonate although just carbonate suffices most of the time) and shift the colors to yellow, orange and maroon using plain old sodium chloride in rather high concentrations. A two-bath approach à la Moersch Polychrome using a slow metol developer worked fairly well too, although here, glycin would probably have helped boost colors. But I don't happen to have any, so I didn't try.
So instead of making the chemistry more complex, I tried to keep things as simple and flexible as possible, which seemed to work quite well. Granted, I didn't bother with RC papers because their uneven coating (mottling) tends to become a problem in lith applications one way or another.

I think if a simple solution were possible, Moersch or similar would already be selling a lith developer based on that principle that works with any paper. I've already went from braindead simple (literally just HQ-TEA and carbonate) to a huge number of additives. The only way I've been able to get proper infectious development to happen at all on Ilford RC papers is:

* Extremely high pH and low sulfite
* Extremely high amounts of HQ and low sulfite
* Adding a secondary development agent along with high amounts of HQ and low sulfite (ie, the EXA approach)

Each approach comes with it's own problems. High pH is very likely to cause fogging and of course the developer lasts maybe 15 minutes if you're lucky. Development will also be quite uneven. High amounts of HQ cause extremely uneven development with every paper, including lithable FB papers. The secondary development agent route has been the most promising method yet for making normal modern papers work consistently... but of course isn't perfect yet either, but does give great results already with some otherwise unlithable papers, like MGV RC.

I'm using Ilford RC papers for this testing primarily because they are known (and I've thoroughly tested) to not normally be lithable (ie, won't get infectious development, only low contrast images) and seem like a good "difficult" target for this goal. RC paper also of course is cheap and quick to process. So, I figure if I can get a good lith print on Ilford RC papers then those principles should be able to carry over to most other papers as well. I actually haven't had much problem with mottling, even in failures. The uneven development is more like infectious development happens at one part of the print, but a shadow elsewhere of the same density lags behind by 2-3 minutes of development time.. and in the extreme HQ-only case, infectious development happens unevenly like that and highlights and midtones also come in unevenly, while shadows will match midtones but the uneven development causes them to not go to black/dark. I've seen some mottling in some really weird experiments, like adding thiocyanate to a lith developer (interesting, but don't recommend) and with zero-sulfite HQ only development.. but those aren't practical for many reasons beyond mottling
 
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grainyvision

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Began working on a new "EXB" developer last night using Phenidone instead of Glycin, and a higher amount of sulfite (30ml of 10%). I was basing it a bit on that patent formula, but that definitely does not work for my purposes.. either that, or benzotriazole is not an anti-fog agent compatible with the idea. The "best" anti-fog in the patent is available on sigma, but $100 for 100g and discontinued. The second best is available and still being made though.

I first tried 1:100 phenidone:HQ and that was way too much phenidone, it just ended up being a crappy continuous tone developer. I tried adding more bromide and/or benzotriazole, but neither helped very much really. Benzotriazole slowed down highlights/midtones a little bit, but after ~100ml it seemed to top out and didn't slow down more in comparison to shadows. Bromide, as with EXA6, only slowed down infectious development. Decided to do a remix using significantly less phenidone and the results were a bit more reasonable, but still with highlights and especially midtones developing too fast in comparison to shadows. I ended up getting some kinda half decent results from a formula approximately this (my note taking was bad and so this is just from memory)

"EXB3" (prototype)
* Water 2L
* 15ml HQ-TEA 20%
* 0.5ml propelyne glycol/phenidone 1% (0.2 or 0.3 probably would've been a bit better)
* 30ml sodium sulfite 10%
* 50ml benzotriazole 2%
* 1ml potassium bromide (0.5ml probably would've been better)
* 8ml potassium iodide 10%(!)
* ~25ml potassium carbonate and/or 10ml sodium hydroxide 3% (pH about 11)

The real breakthrough to get any reasonable results was to add iodide and increase the pH. Beforehand it I couldn't get the midtones and highlights to slow down. Adding iodide seemed to make infectious development a bit faster and everything else noticeably slower. Increasing the pH made infectious development begin faster while highlight/midtone speed remained about the same.

Results were very different in color and more subtle. Colors tilted toward cool lilac highlights and warm olive shadows.. Not exactly a color spectrum I've seen on any lith print before. Blacks were comparable to EXA6 and the developer seems to increase the speed of the paper by 1 stop compared to EXA6, so I'd use a starting point of 1 stop less than you'd use for typical lith printing and/or 1 stop over exposed from a normal paper developer. This developer also lasted significantly longer both in terms of time and prints than EXA6. This formula also produced a considerably finer grain print than EXA6. This is definitely not a complete formula yet, but can maybe produce some half decent results. The biggest problem is just that the highlights and midtones still develop a bit too much in comparison to shadows (ie, shadows are quite a bit faster, but not "exponentially" faster, limiting contrast control techniques)

What I've been trying to research and find is a chart or something detailing different restrainer/anti-fog effects on different developing agents. I've found stuff for the response to bromide, ie, that phenidone is only somewhat sensitive and hydroquinone is extremely sensitive. However, I've not been able to find anything similar for iodide, chloride, benzotriazole, etc.. Looks like if I really want that info though, I'd need to do the experiments myself and measure them. Also even with that knowledge it's not exactly easy to adapt. For instance, benzotriazole does seem to have some effect on the development action of hydroquinone, but seems to do nothing against the highly reactive quinone responsible for infectious development.
 
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grainyvision

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Yet another update on EXB developer series. It's pretty long, so I'll just summarize it here and give the pictures. Full report at https://grainy.vision/blog/magic-lith-prototype-update-5-exb-developer-series

Basically I've figured out a great neutral color /cooltone lith developer with the following interesting properties:

* Extremely deep blacks, full range of contrast adjustment techniques with very good separation between highlights, midtones and shadows
* Not overly sensitive to sulfite (it'll slow down infectious development a little bit, but does not affect depth of blacks)
* Fairly long tray life both in terms of time and number of prints that can be processed (>1.5 hours and >10 8x10 prints)
* Very consistent across many prints if pH adjustments are made (need to do research on making a decent 12 pH buffer to cure the pH problems)
* Some but not a great sensitivity to additional bromide, thus the consistency across prints
* Neutral or cooltone color spectrum depending on paper, ideal as a "blank slate" for toning
* Edit: also, it works on "difficult" papers. Tests include Ilford MGV RC and Warmtone RC. I expect due to the unique mechanism by which infectious development is activated (ie, by the oxidation of phenidone rather than hydroquinone itself) that this developer will give good results with any paper, as long as a high amount of iodide doesn't damage the emulsion anyway.

The TL;DR; of the formula is an almost homeopathic amount of phenidone (0.2ml of 1%), a high amount of sulfite, a high pH, almost insane amount of iodide, and some antifoggant. You can see the results attached (note the overly yellow print is actually stained due to not fixing long enough. This requires double or triple the normal amount of fixing time in TF-4).. EXB4 used 0.2ml of phenidone 1%, while EXB5 used only 0.1ml, both formulas being extremely similar otherwise. Note these are 5x7 prints, so more paper grain visible than previous images using 8x10 sizes
 

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