I shared here previously the formula for ModernLith. Given the complexity of it however, one might believe that formulating a lith developer requires a degree in chemistry, or access to some specialized lab. Ultimately, both of those things would definitely help, but I’m proof that neither of things are required. My knowledge in chemistry is from the very little I remember in high school, and from reading as much as I can make sense of on the internet. Basically, if I can make a lith developer, then you definitely can too. Making other types of developers is not something I know nearly enough about, other than that step-wedge tests will give you a nice summary of how badly you’ve failed.
The best method for easily mixing and testing lith developers is to mix them immediately before use in the darkroom. Most people lack magnetic stirrers and oxygen-free atmospheres in their darkroom though, so this can be very painful to do when you’re talking about a solution life of 1-2 hours and potentially taking 30 minutes to mix from powder. The answer is to make a series of % solutions. These % solutions should use a solvent that will be fairly inactive as a component as a developer, dissolve enough of the chemical to be reasonably useful, and to not accelerate the decay of the chemical in question. This lead me to 2 primary solvents. Water of course being one, and propylene glycol being the other. Many things are not soluble in glycol, this includes often used components like sulfite and bromide. Though glycol is cheap, it also isn’t nearly as close to free as water. So, the ultimate idea is to dissolve everything into water that won’t decay. Most developing agents will oxidize in plain water, and become inactive or cause other problems. Many are more resistant to oxidation in a strongly acidic solution, but this require using more alkali in the final working solution to counteract it, and of course dealing with the potential contaminate, such as sulfur introduced into the solution by using sulfuric acid as a preservative (sulfur is roughly equivalent to sulfite for developer purposes). Either way, it’s easier to just dissolve them into something non-ionic which will basically prevent the developing agent from being active and capable of oxidizing. This is what glycol does as a solvent. Note that triethanolamine can also be used for this purpose, but it is active in developers, giving effects I’ll describe later.
Note that most commercial lith developer formulas use paraformaldehyde as a sulfite “battery”, potentially weak developing agent, emulsion hardener, and probably a few other effects. I have refused to use it since it’s a known carcinogen and I feel like there are plenty of ways to make a lith developer without using it. I won’t cover it at all, and assume you only want to formulate a formaldehyde-free developer.
Essential solutions
10% hydroquinone in propylene glycol — dissolved by heating 400ml of glycol to ~140F and stirring in 50g of hydroquinone, then top to 500ml with glycol
10% sodium sulfite in water — Dissolved by taking 400ml of hot water and stirring in 50g of sodium sulfite, top to 500ml with water. Solution should be stable for 6 months to a year in a sturdy plastic bottle (sulfite will slowly oxidize even in plain water)
10% potassium bromide in water — Dissolved by taking 400ml of water and stirring in 50g of potassium bromide, top to 500ml with water.
20% potassium carbonate in water — Dissolved by taking 400ml of COLD water and stirring in 100g of potassium carbonate, half at a time, top to 500ml with water. Solution will warm up significantly. Sodium carbonate can be used instead, but only a 10% solution should be made or else the solution may crystalize with slightly cold temperatures and it will require a LOT of stirring.
Other useful solutions
10% sodium chloride — non-iodidzed (I use kosher) table salt
0.1% potassium iodide
5% ascorbic acid in propylene glycol — similar to hydroquinone, requires significant stirring and will be slightly acidic in water
5% sodium hydroxide in water — “lye” solution. Can be used when a higher pH is required than carbonate than easily provide (greater than ~11.2), or to counteract a strong acid being used without as much carbonate.
0.1% benzotriazole in water — Dissolved by taking 400ml of hot water and stirring in 0.5g of benzotriazole. Top to 500ml with water.
10% potassium oxalate in water — Useful as a chelating agent among other things, suspected to help preserve ascorbic acid when used with tap water
Useful equipment
pH test strips. You can buy 100 strips for like $6 on amazon. I can’t believe it took me so long to invest in some. I buy the types with 4 strips of color that can be matched to a chart and read both alkali and acidic pH.
5ml-100ml graduate. For mixing a “concentrate” just before dumping it into a larger graduate to make the working solution
1L graduate. For the working solution
1ml syringe. Useful for measuring tiny amounts.
2ml-10ml syringe. Useful for larger amounts of water based solutions where more precision is needed than the graduate
Plenty of bottles. Some solutions require heavy duty chemical bottles, like the carboante and sulfite. Others can use recycled soda bottles like for potassium bromide. Note that carbonate should not be stored in glass bottles.
Laser temperature reader. Can be very useful for getting exact control tests and conditions etc by being capable of easily and quickly measuring the temperature of your working solution. Definitely the most optional part of this list
I have some glassware lab beakers and a magnetic stirrer/hot plate combo. Definitely helpful, but you can get by without it.
Infectious Development
Before I get into anything else, lets at least touch on this. Lith printing hinges on the unique concept of “infectious development”. The exact mechanisms behind how this works, even today, is not fully understood. However, the basic concept is agreed upon. Basically, when hydroquinone develops a silver halide grain, it will convert the silver halide to metallic silver and release the halide (typically bromide, but can also be iodide or chloride) and the hydroquinone itself will “partially” oxidize, turning into a radical. This radical is extremely reactive and will basically ignore all restraints and develop any nearby silver grain it touches. When this occurs, the halide is once again released, but this time the radical will fully oxidize into benzoquinone. Benzoquinone is the primary reason why lith developers smell so funky and plasticy. It seems to be inactive in the developer solution, though I’m not completely sure. Benzoquinone can be converted back to hydroquinone by some chemical means, such as by ferrous ions. It can also be converted to hydroquinone-monosulfonate (HQMS) I believe by sulfite (or maybe only the radical can be converted??). HQMS is a fairly weak but stable developing agent on it’s own, but it is capable of superadditivity. It is used in some formulas such as famously the official E-6 first developer formula. Overtime, the various quinone compounds will oxidize etc even beyond what is described here and undergo irreversible polymerization to become totally inactive and incapable of reverting back to an active state. There is no chemical here as it turns into a huge number of chemicals. This is likely the primary component of “old brown”, or oxidized and dead developer, and is responsible for it’s brown appearance. I believe most developing agents undergo a similar process, but not all will be brown. Phenidone for instance will turn pink, and ascorbic acid orange.
Basic formulation
A basic lith formula consists of the following:
A solution with pH at or above 10.5
Some amount of hydroquinone
Some amount of potassium bromide
And a relatively small amount of sulfite
For instance, here is a reasonable formula:
1g hydroquinone
0.5g sodium sulfite
0.5g potassium bromide
6g potassium carbonate
to 1L of water
This isn’t a tested solution, but I’d assume it’d give lith results with lithable papers, maybe with more bromide being required for something more optimal. However, with this very basic formula you could encounter various problems, such as uneven development, very poor and inconsistent tray life, pepper fogging, and inability to enter infectious development with non-lithable modern papers. So, let’s first get into what makes a lith developer fail.
The Sulfite Ratio
All lith developers are especially sensitive to two sulfite ratios. The first ratio is sulfite to total solution. The second is sulfite to hydroquinone. The way too much sulfite prevents infectious development is that sulfite will scavenge hydroquinone radicals. Sulfite will either convert these radicals back into hydroquinone, or into HQMS. I believe the process is fairly random. Either way, too much sulfite means that the radical can’t move very far before touching a sulfite ion and be scavenged. If the radicals can’t move far enough to touch a silver halide grain, then infectious development will not occur. This ratio is mostly regarded to be 2g/liter. I’ve successfully made lith developers which exceeded this, but the solutions came with a ton of other problems, primarily a very high pH which caused rapid decay, fog, extremely fast and uneven development, among other problems. For a pH of ~11, I’d say the magic ratio maximum is closer to 1.2g/liter.
Now, the sulfite to hydroquinone ratio is less about sustaining infectious development and more about tray life. 1g of each per liter will make a reasonable lith developer. One thing sulfite does, just in general, is absorb oxygen. It does this even outside of water, which is why I wouldn’t recommend buying a 5lb bag at a time. Oxygen absorbed by sulfite is oxygen that can’t oxidize the precious hydroquinone in solution. There’s various chemistry stuff that prevents it from ever being perfect (OH ions or something), but you can think of it in this way. If you add a surplus of hydroquinone, like say 2g, then oxygen will tend to go for the hydroquinone instead of the sulfite. The result will be a faster activity decay rate, even if the developer itself may last (ie, produce infectious development) for longer. There is another concept to consider here though. Hydroquinone radicals themselves seems to also cause hydroquinone to decay. Thus, a strong hydroquinone solution will decay to dead faster than a weak hydroquinone solution. This isn’t a steadfast rule, especially when adding in some other chemicals.. but is something to consider. Also, too many hydroquinone radicals in solution produces various effects like pepper fogging and general staining. Thus I personally try to use a matched or just slightly different sulfite:hydroquinone ratio in my own formulations, like 1:1 with sulfite. Not to mention that using less hydroquinone means you save some money on not watching the developer die in the tray after 30 minutes.
Restrainers
There are two primary restrainers we’re concerned with. Bromide, and other things. Bromide behaves in a unique way compared to other restrainers. Chloride is similar to bromide, but behaves as more of a middle ground between bromide and other things. Iodide behaves almost completely differently. Anyway, potassium bromide will slow down the overall development, as expected of a restrainer. It will increase the overall induction time (ie, where the low contrast image is fully developed before infectious blacks start) and too much bromide with some papers can cause the induction time to be 1 hour+, which of course is not desirable. Without any bromide, infectious development tends to start before the induction period is complete, leading to uneven and difficult to control development. Bromide also is the only restrainer I know of which will slow down overall rate of infectious development. Bromide also is extremely potent against hydroquinone, but less potent against most other developing agents, including ascorbic acid.
And now, everything else. The important thing is that other restrainers tend to not affect speed or depth of infectious development, but do affect how the “starting point” (where highlights will show up) and “end point” (how dark midtones get) of the induction period image. Benzotriazole is especially potent, shifting the starting point so that more exposure is required for the same amount of development. However, benzotriazole affects the end point even more. Thus, if midtones are too dark before infectious development really gets going, benzotriazole can be used to lighten them without losing highlights (when compensating for additional exposure time).
Iodide behaves in a way similar to benzotriazole, but can cause many problems. It can cause yellow staining on the borders and significantly longer (2x or 3x) fixing times should be used, as iodide containing developers cause some silver iodide to get stuck in the emulsion which is significantly more resistant to fixing. Chloride also gives this behavior, but does not require the additional fixing time. Basically iodide/chloride will shift the end point, preventing midtones from darkening as much, but are less effective at shifting the starting point. Because of the yellow staining issue, not too much of either should be used, and honestly I’ve had more consistent results just sticking to benzotriazole. Iodide/chloride tends to be more effective for restraining developers other than hydroquinone. Without a huge surplus, they will not typically affect infectious development rate.
Thiocyanate is also an interesting component. It behaves like a very strange restrainer in lith development. It will increase induction time like bromide, but also reduce the time when infectious development begins to occur. Very much at all though can lighten blacks due to it’s solvent action, dissolve highlights, and cause silver sludging that can be annoying to remove. (silver sludging will look like an iridescent sheen on the borders which can be removed by rubbing under hot water and not removed by chemical means). A very small amount though can enhance the depth of blacks and increase overall contrast
Secondary Developing Agents
Secondary developing agents can be used, but one should be used which is NOT superadditive with hydroquinone. A superadditive secondary developing agent will not exhibit good contrast and will consume the sulfite in solution quickly. For example, metol and phenidone should not be used.
Glycin is a very soft-working developing agent I used in an early lith developer formula. With a small amount and proper restrainers it will increase the contrast and range of colors in the induction period image. This tends to be especially tilted toward extremely warm tones. Very much at all though will cause blacks to develop prematurely and it then won’t really behave like a lith developer. Even with a small amount I found it difficult though to get the full range of contrast that lith developers enable.
Ascorbic acid (and it’s salts) is a developer that is extremely similar to hydroquinone, but will not (usually) undergo infectious development and is measurably weaker. It can be extremely active and is reported to undergo something similar to infectious development at extremely high pH, like pH 13 or 14. With a pH so high though a lot of other problems tend to occur like fog that can’t be easily solved with restrainers, extremely short tray life, and uneven development. I’ve done some testing for an ascorbic acid only lith developer, but could never get it to work properly. Ascorbic acid also tends to ignore actual exposure levels with limited restrainers and will darken anything that’s been exposed completely to black with enough time. Ascorbic acid is extremely interesting though because it’s been reported by many sources to be a sacrificial antioxidant that will help to preserve sulfite. Like hydroquinone, it also can behave strangely depending on paper choice. Some papers seem to just barely be touched by ascorbic acid, while others can quickly go to pure black with it. Thus, with a suitably small amount, moderate pH (<pH 13), and restrainer, it will become mostly inactive for development purposes, but will help to increase tray life by preventing the sulfite from freely oxidizing by oxygen, and instead the sulfite will only be oxidized by the hydroquinone products. Even then, it still appears to modify how many papers will behave. For some papers it has a restrainer-like effect that slows infectious development rate while also allowing more bromide to be used without increasing induction time significantly. For other papers, it has a development accelerating effect. As a formaldehyde replacement, ascorbic acid ultimately works quite well for increasing tray life, but the amount should be tuned for different paper types. With Ilford RC papers, ascorbic acid tends to act as a restrainer. With Ilford FB and all foma papers, it tends to behave as an accelerator. Thus, for accelerator type papers, a small amount should be used, or a higher amount of restrainer added to compensate.
Pyrocatechol is one developing agent that could produce very interesting and colorful results due to it’s action as a staining developer. I’ve not tested it however, and it’s very poisonous. I have some in my cabinet marked to by used for this at some point but I haven’t gotten around to it. Pyrocatechol is also very similar to hydroquinone in how it works as a high contrast developer, but instead of undergoing infectious development, it will produce a stain that hardens the emulsion. I suspect very much would cause infectious development to be prevented due to this hardening effect, especially on modern non-lithable papers. However, I just don’t really know. If it does not hamper infectious development too much, it could be used for an entirely new set of possible colors in a lith print. The stain is reported as being a cool brown. One note however is that such a stain may not be stable over time and can easily be bleached by any sulfite or acidic solutions. This includes acidic fixer and stop bath, as well as hypo-clear bathes. If anyone tests this out though, please comment here about your results. Technically hydroquinone is also a staining developer, but for unknown reasons does not typically give staining when used in lith printing, potentially due to using a high pH.
Effect of Ph
I’ve personally found that a pH of around 11 is the most ideal. However, other pH levels can be used. pH will directly affect almost all aspects of the developer. A higher pH will decrease overall tray life, increase development speed, and especially increase infectious development rate. A higher pH tends to also give less colorful results and higher contrast. Meanwhile, a lower pH will basically do the opposite of all of that. One interesting effect on pH is how it interacts with sulfite. At a lower pH, like 10.5, less sulfite should be used as the sulfite will be more effective at preventing infectious development. At a higher pH, more sulfite can be used.
Other Additives
Triethanolamine (TEA) has a number of effects in a lith developer. TEA will scavenge radicals, behaving somewhat like sulfite in terms of preventing infectious development, though this requires a fairly large amount, like 50ml/liter to completely prevent. In some tests, it seems that very much TEA can cause infectious development to proceed unevenly. Whereas a lack of bromide causes infectious development to start at the edges, TEA instead causes infectious development to start in the center. I’m unsure why. TEA does however function as an antioxidant and chelating agent, thus extending the tray life of the developer. A large amount of TEA and hydroquinone will actually produce a normal contrast developer that is quite long lived, over 6 hours in my testing despite being a very dark brown solution. I suspect that TEA and hydroquinone in alkali solution will form some undocumented developing agent which is of more normal contrast and longer life than hydroquinone, though seems to also be especially sensitive to bromide. Regardless, if any TEA is used, I recommend using a small amount, like 5ml or so per liter.
Potassium Oxalate is what I use in the ModernLith formula. It seems to have far less photo effects than TEA. It is of neutral pH, can function as a mild anti-foggant/restrainer with ascorbic acid, and is a chelating agent also capable of neutralizing metal ions in tap water (and thus helping to preserve developing agents). I believe that a common contaminate though is iodide, which means that very much can cause staining and other problems. It’s also a somewhat hard to find component especially in grades higher than 98% purity. Assuming that distilled water is not used for everything though, I’d recommend using a small amount of oxalate. Note that sodium oxalate is similar, but is much easier to find and is not nearly as soluble in water. Oxalate can cause a weird precipitate powder to collect on trays over time. I believe these are iron oxalate complexes from tap water, as well as calcium oxalate… but I don’t really have a way of testing what the powder is. I can only confirm that it is not silver oxalate due to not being flammable (silver oxalate is very flammable and actually explosive with shock, so that’s a good thing it’s not being produced in any measurable quantity)
Potassium Ferricyanide is an interesting addition and if used, very small amounts should be used. It seems to produce more colorful highlights, but also can bleach highlights as well as reduce the overall latent image, requiring more exposure to compensate. I’ve not done much testing of this with lith developers, but has proven interesting in normal developer formulations.
Solvents
In propylene glycol, the following components are known to be soluble:
hydroquinone (fairly easily for 10%)
phenidone (1% is difficult to dissolve, 0.1% is pretty easy)
ascorbic acid (8% seems to be the max, aim for 2.5% or 5% for an easier time)
pyrogallol and pyrocathecin (untested, but commonly reported)
In Treithanolamine (TEA):
hydroquinone (very easily once heated, over 20% solution is possible)
glycin (add slowly a bit at a time to prevent clumping, quite slow to dissolve, 10% solution or maybe more is possible)
pyrogallol (untested, but commonly reported)
pyrocathecin (untested, but commonly reported)
Other potential solvents include ethelyne glycol (poisonous especially to animals!), glycerin, alcohol (note most developing agents will still oxidize in alcohol). Photo properties of these other solvents hasn’t been well researched by me.
Note metol can be dissolved in glycol, but only once neutralizing it by putting it into a small amount of water and TEA mixture. Keeping properties are known to be poor with this workaround though.
Testing
Testing the developer is where the fun starts. I recommend actually not using a step-wedge, as they can hide various problems and cause some problems that you wouldn’t have in most normal images. The large blocks of black in a step wedge print tends to give skewed results in any lith developer, despite not causing any real problem in actual printing. So, I recommend choosing a fairly normal contrast image on fine grain (preferably medium format) film. There should be some small blocks of black that you actually want to be black. Start with 2 or 3 stops of over exposure. A heated setup can be very useful to speed things up, though heating may cause some fogging tendency with some papers and developers. I personally use a sous vide water bath set to 125F, and then float the developing tray on top of the water. This will keep it fairly warm but not hot, maybe 90F. Once the developer seems to work for one contrast, use another contrast by either increasing or decreasing the exposure. Does contrast actually change and does infectious development still occur? If so then you probably have a successful developer. If not, then you’ll need to revise things, unless you’re ok with a fixed contrast developer. My EXA series of developers technically were “lith”, but only worked well across a very limited contrast range. The results were great but not flexible for all printing needs. Once you have a developer that works well on one paper, try a few different papers, especially a different base (RC vs FB) and different manufacturers. It’s perfectly acceptable to create a developer tuned to exactly one type of paper, but knowing that it only works well on one type is something to keep in mind when preparing for a printing session. For instance, ModernLith, though giving reasonable results on all papers, is especially great on MGV. So, MGV is the paper I typically plan on using when setting up for a session. Make sure to take notes of every addition to the developer, and mark it on the test print using it. Dry-down is definitely a thing and the results that look stellar while wet can suddenly look not great while dry. Black depth can be especially deceiving like this, but also overall color and tonality. Being able to cross-reference a series of prints to figure out what chemical you added that caused things to go wrong, or right, is an extremely valuable resource.
Conclusion
Overall a lith developer is complicated with a lot of weirdness, but by making various % solutions it can be extremely easy to test to see what the results are, and of course you can produce unique results unlike those seen in other lith developers. In my journey in formulating lith developers I was absolutely blown away by how a single type of paper can give so many different appearances just depending on the paper formulation. I’ve seen Ilford MGV RC for instance as both grainy and smooth, deep blacks and brown blacks, extremely cool and extremely warm tones, etc. Despite how daunting the process may seem, it gives you unheard of flexibility even if you only use a single type of paper. I highly recommend it for anyone who wants to learn more about the chemistry of lith printing and printing in general. It can be a bit of an obsession once you get started, but when you finally get prints working just the way you like, it will all be worth it.