Doing Densitometry for Lith Printing

Lith Printing has traditionally be very uhh "feel" based. Since it has so many variables that go into it, it can be quite difficult to create two prints that are exatly the same. I did not solve that problem, but I did manage to create 2 prints which measure quite closely to the same when using a densitometer. And using that knowledge, I've been testing various lith print developer ingredients to try to better inform my design of lith printing developers. Here is the data I have so far:





The exact design is that I do a series of exposures of a 21 step step-wedge on Ilford MGV RC paper. I then use developer GVLith #7 (BasicLith with 0.03g/10ml PEG-3350 added) diluted 10+10+400 as the control and the tester is a modified version of that developer. The exposures are +0 stop, +1 stop, and +3 stops. I then do the +0 exposure again to measure how the developer has aged. +0 will typically provide a highest visible step on the step wedge of about 11 for reference. I develop the print for a visual aim of steps 1 and 2 looking indistinguishable and black. Being under darkroom lights, this is of course a bit fuzzy, but it is consistent enough that I can replicate it within a relatively small amount of measurement error. I also record speed of development. I first record when the first image becomes evident, and then when the full image appears to be there and induction period seems complete, then when the first black tone appears, and finally when the print is complete. These are also quite fuzzy of measurements, but are good enough to spot big trends.

I have tested the following thus far:

* no PEG-3350 present in the developer
* Control (BasicLith with PEG-3350)
* +3ml of 10% sodium hydroxide
* +3.5g sodium sulfate

The list of things I intend to test is as so:

• pot bromide addition (or subtraction?) 3ml of 10%
• BZT 0.5ml of 1%
• sodium chloride 10ml of 20%
• sodium thiocyanate 0.5ml of 1%
• pot carbonate 8ml of 20%
• dilutions, 5+5 vs 10+10 vs 20+20
• TEA 2ml
• sodium ascorbate 0.2g
• glycol 20ml (confirm it is inactive and has no effect)
• Final GVLith formula iteration using the info learned
• Synthesized benzoquinone/decayed hydroquinone (alkali, +peroxide, then neutralized with acetic acid)

If anyone has any suggestions of other things that would be interesting to test, leave a comment here!

Thus far, I've learned:
* hydroxide decreases overall contrast, weakens the "midtone dip", and massively increases development speed
* sulfate is an effective development accelerator, but will come with a decrease in dmax (and yields slightly brown blacks) when printing for low contrast aims (ie, more exposure)
* PEG increases developer linearity (developing blackest tones first), strengthens the "midtone dip", and overall slows down development while increasing contrast

There is no article at the time of posting, but I will eventually have a blog article discussing all of this here: https://grainy.vision/blog/lith-printing-densitometry (since Photrio doesn't allow editing posts after 24 hours, so this is posted so that people finding this on Google in a year don't have to dig through a million posts to find the final resulting info)

The formula and additional info for BasicLith has been posted here: https://grainy.vision/blog/basiclith

Anyway, if anyone has any suggestions or comments on presenting this data, I'm all ears! I've found the actual densitometry stuff is super boring and tedious, but it only takes about 1.5 hours per test run (testing + measurement) so it's not too awful.

Please confirm, that you really used Sodium Sulfate in this test 4, Sulfate with an A. The amount you used and the effect very much point at Sodium Sulfite.

PS: Kudos for the massive swath of test data, I know very well, how tedious and boring it can be to create these results. Still digging through the implications of your results ...

Rudeofus said:

Please confirm, that you really used Sodium Sulfate in this test 4, Sulfate with an A. The amount you used and the effect very much point at Sodium Sulfite.

PS: Kudos for the massive swath of test data, I know very well, how tedious and boring it can be to create these results. Still digging through the implications of your results ...

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No definitely sulfate. Actually purified myself because the source I had was a bit impure (had to recrystalize cause it had some insoluble junk). Sulfite would slow down development and decrease dmax

@earlz Given that sulfate was used in various 'tropical' developers as it counteracts emulsion swell, there should be an interaction with the PEG (which acts by swelling the gelatin) at some point.

Lachlan Young said:

@earlz Given that sulfate was used in various 'tropical' developers as it counteracts emulsion swell, there should be an interaction with the PEG (which acts by swelling the gelatin) at some point.

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I have tried to force and minimize emulsion swelling and the results are not as interesting as I would've thought. I lack hard data still, but I've done stuff like soaking in hydroxide or using thiocyanate to increase swelling and the results are inconsistent with more swell = slower or faster.

I believe the reaction is actually quite deeper and more specialized. I found a paper somewhere which studied the behavior of hydroquinone and benzoquinone in sodium sulfate containing solutions. Sulfate only slightly increased the decay rate of hydroquinone but significantly increased the decay rate of benzoquinone. Benzoquinone being the primary oxidation product of hydroquinone. It did not mention how it affected overall radical behavior. I'm unsure of the exact action, I but My personal hypothesis is that sulfate removes the benzoquinone attached to the silver grains which may be partially responsible for the distinct difference between the induction period and the infectious development period

Here are the results I've collected so far:





Here are my own explanations of this data thus far:

Terms:

• dmax depth — How dark black tones are capable of being
• shadow contrast/infectious development amount — How much of the image that is below middle grey undergoes infectious development. Less contrast = more overall infectious development
• linearity — Tendency of infectious development to only develop the blackest tones first. Less linear developers typically would result in lower shadow contrast
• Tone — Most lith printing developers would be described as warm, but there is slightly warm and very warm.
• Midpoint Dip — The midpoint dip is a term used to describe densinometry results of the point on the graph in between the shadows and the highlights. When the midpoint dip is strong, the curve at this part is very steep. When the dip is weak, it is much less steep. Basically this equates to how dark the midtones actually get and is a good indicator of linearity and overall contrast and how different the density is between infectious development zones vs induction development zones.

Chemical addition observations:

Hydroxide/low buffer alkali will increase overall developer activity, and will oddly enough make uneven development less likely. It will cause an increase in dmax, but also an overall darkening of shadows and mid tones, leading to lower contrast shadows and a weaker midpoint dip. It seems to promote infectious development in more exposure at the same time, rather than only the darkest tones first.

PEG-3350 will specifically increase linearity of the developer, make the midpoint dip significantly stronger, and result in an overall increase in contrast of the developer. It is also a restrainer and will slow down development to a minor extent.

Sodium Sulfate is effectively an accelerator for lith printing developers. It will significantly increase the speed of development to “done”, but this benefit comes with a cost. If you want steps 1 and 2 on your final image to be the same, effectively black, and the image is quite over exposed to decrease contrast, then sodium sulfate will result in a significant decrease in dmax, giving slightly brown black tones, but also a significant decrease in development time. In my own tests, this time difference can be significant! 7 minutes vs 3.5 minutes. Thus, while sodium sulfate is definitely useful, the amount to use in a developer should be only a small to moderate amount. Enough to get the increase in development speed for lower contrast prints, but without the noticeable decrease in black depth. Despite being a development accelerator, it does not appear to cause the developer to decay more quickly. So usage of sulfate will increase the total amount of prints you can get from a working solution of developer. Sulfate will also cause tones of the highlights to shift to slightly more yellow and cause highlights to appear slightly lighter because of this effect (yellow highlights on white paper)

TEA decreases the speed of overall development, but especially makes infectious development slower. When aiming for a high contrast level, TEA will cause no noticeable changes to the image, but when aiming for a lower contrast level, it will increase the linearity of the developer and make the midpoint dip significantly stronger. It is known to have minor preservative effects as well, but this does not outweight its slow down in development speed.

Sodium Chloride is a developer accelerant, especially increasing the speed of infectious development and shortening the induction period. It behaves very similar to an addition of hydroxide when targeting a high contrast aim for development, but without affecting the tray life. It significantly decreases the linearity of the developer and soften the midtone dip, but also increases the density of highlights. However, when aiming for a low contrast aim, the depth of blacks tones and overall shadow density is less than compared to a simple hydroxide addition. The overall end result of this is that a developer with sodium chloride will be faster, but lower in contrast and with less linearity of development.

Benzotriazole is an anti-fogging agent and restrainer. It will especially prolong the induction period of development, but only slightly affect the speed of infectious development. Benzotriazole has anti-fogging properties and may be added to a developer in order to counteract fog from old materials. On its own without any fog on the materials however, it will increase contrast and significantly increase developer linearity. It will slightly decrease the overall dmax of the print as well, though this is a very minor effect only revealed by densitometry. BZT will also cause a moderate decrease in high-mid and highlight density and greatly strengthen the midtone dip. In practice, BZT feels similar to decreasing the speed of the material and some of these differences are nullified by increasing exposure to compensate for that.

Thought I was the only one playing with BZT in lith.
Thank you for this work, and your blog, but being mentally lazy probably will not affect my methods.
I have a large supply of Kodalith Super r/t, and maybe a lifetime supply of Kodak Transtar tp5 which liths quickly and reliably and responds well to alterations of A and B. In fact, if I ever run out of the Transtar I will probably give up photography altogether. It's like cooking a marinara, it's always good but sometimes it's fantastic and sometimes magic. There is a phenomenon I have experienced and have heard musicians talk about, where a track is recorded that feels blah, but come back the next day and it is magical and there is no other explanation other than the molecules floating around are different.

Ashley -- thank you for this ongoing work and publication.

Well this is way beyond my knowledge of lith but this looks crazy. Will read more thoroughly when/if my skills improve.

Rich Ullsmith said:

Thought I was the only one playing with BZT in lith.
Thank you for this work, and your blog, but being mentally lazy probably will not affect my methods.
I have a large supply of Kodalith Super r/t, and maybe a lifetime supply of Kodak Transtar tp5 which liths quickly and reliably and responds well to alterations of A and B. In fact, if I ever run out of the Transtar I will probably give up photography altogether. It's like cooking a marinara, it's always good but sometimes it's fantastic and sometimes magic. There is a phenomenon I have experienced and have heard musicians talk about, where a track is recorded that feels blah, but come back the next day and it is magical and there is no other explanation other than the molecules floating around are different.

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I use to have a really great paper for lith printing, but then I ran out of it. I couldn't find any more reliable source of it, and trying to make sense of ebay listings for expired paper is a job for someone much more insane than me. I had some old paper which could reliably lith, but it wasn't anything too exciting... I decided to start trying to formulate my own lith developers to see if I could make modern materials work. Oddly enough my controversial favorite materials to work with (RC papers) ended up being the easiest to control and create a lith developer for

Craig75 said:

Well this is way beyond my knowledge of lith but this looks crazy. Will read more thoroughly when/if my skills improve.

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I don't expect most people to really understand or care about these effects exactly, but these are basically exactly the kind of notes I have wished existed for the past year when I started trying to formulate my own lith developer. It seemed like there was a ton of different ingredients added to the public formulas, but no explanation as to why, and so many interesting effects talked about in patents and scientific which was completely untouched by public formulas.

My definite immediate goal with this data is to formulate a series of lith printing developers, each with a different artistic aim. From what I can tell right now, it should easily be possible to create a "grit and grime" developer as well as a "colorful and dreamy" developer. The final end result of all of this research might even be a book if I ever have the motivation to actually go that far. I'm unsure I actually have that much dedication though. But I find lith printing and the chemistry formulations to be an extremely interesting and unique challenge

Very good work. When I was younger I made a sample book of different fiber base papers, with different developers, and several different toners. Amazing colors. All those papers are extinct now. Still applicable.
I still have a horde of Forte PWT, I like current Foma papers, especially Fomatone, great paper.

grainyvision said:

My definite immediate goal with this data is to formulate a series of lith printing developers, each with a different artistic aim. From what I can tell right now, it should easily be possible to create a "grit and grime" developer as well as a "colorful and dreamy" developer.

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@grainyvision: While many papers are not easily lithable, almost all are amenable to second pass lith where one does a first pass development using a regular print developer, rehalogenate-bleach the print and redevelop in a lith developer. This has the added advantage that the choice of the bleach can influence the result one gets from second pass lith. Curious to know if your formulations offer any distinct advantage over second pass lith with a regular lith developer. Have you done a comparison with second pass lith on the same RC paper?

Raghu Kuvempunagar said:

@grainyvision: While many papers are not easily lithable, almost all are amenable to second pass lith where one does a first pass development using a regular print developer, rehalogenate-bleach the print and redevelop in a lith developer. This has the added advantage that the choice of the bleach can influence the result one gets from second pass lith. Curious to know if your formulations offer any distinct advantage over second pass lith with a regular lith developer. Have you done a comparison with second pass lith on the same RC paper?

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My favorite part of lith printing is how much contrast control is available even when not messing around with formulations. That kind of aspect is mostly lost in second pass. Also cleanliness is extremely annoyingly relevant for second pass. I can't even begin to count the number of times I had a great print, but then find a small dot of black from a drop of bleach, or weird solarization in the shape of a fingerprint. I'm not exactly filthy in the darkroom but requiring such very strict cleanliness standards is highly annoying for me.

I have done some second pass, but typically I stick to EasyLith for second pass. The reason is that my own formulations thus far can not match the tray life that EasyLith's properietary formula gives. Also the results of second pass involve so many more variables being added to the mix that I'd have no idea how to consider that for densitometry. I do really love the look of a second pass lith printed image on Ilford MGV when using copper sulfate bleach though.

For second pass formulation. My own experience is that it is similar to lith printing with vintage papers. You likely want a bit lower pH, a considerable amount more bromide, and likely a bit more sulfite... basically all things which slow down the activity of the developer and increase stability.