EXG1, a minimal 2 part Glycin film developer

[grainyvision]

earlz submitted a new resource:

EXG1, a minimal 2 part Glycin film developer - A sulfite-free, full speed, shelf stable developer which is ideal for pushing modern films

EXG1 is a minimal glycin developer contained in 2 shelf-stable solutions. It is designed to be a base for further modification, but works great as-is.

Behavior

The developer features sharp "natural" grain, meaning it is definitely not fine grained, but also does not intensify grain like say Rodinal. One of the most interesting properties is that when pushing film it does not make the grain larger, but may make it more obvious just due to contrast differences. Overall tonality is...

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[grainyvision]

I reduced the carbonate levels to just 45ml of 20% solution per liter and this seemed to tame highlight density a bit. If doing alt process stuff like lith printing where a long scale negative is ideal, then 60ml is good but otherwise I'd recommend actually reducing it to 45ml and increasing development time just a hair, maybe 5% or so. Oddly enough, decreasing the carbonate also seems to increase grain levels.

I also made a prototype test formula based on this called EXG2. You can look up my previous posts about that, but basically it's a single solution water-free glycin+phenidone+TEA developer. I haven't done nearly enough testing yet, but it does seem to give full shadow speed and some extreme highlight compensation. More modifications required for good printable negatives though. The ones that came out of it were on the lighter side. Due to it's extreme compensating nature, it also is hard to judge for a "best" development time. I'd almost say you could have film shot anywhere from +2 stops to -1 stops processed at the same time and get good results. Despite being so compensating and somewhat low contrast though, it is also extremely grainy, like rodinal.

Anyway, attached are some example pictures I have from EXG1

One thing I've noticed is some differences between film I processed when it was mixed fresh is significantly less grainy than the film I've processed recently with it less fresh. I'm unsure if this is due to process diffferences. Temperatures are on average about 2-4F higher when developing, I compensate by instead of 11m doing 10.5 for instance. There also might be difference in agitation or something. The tonality and density is the same across them, just increased grain. It may even come down to measurement errors since the solution is so viscous. I might modify some later by adding some glycol. This in theory should give minimal difference in results and shelf life, but make it a lot easier to pour and use say 20ml instead of 10. I also suspected if there is a difference in the film itself, since the biggest difference I've seen grain levels in is with FP4+. Definitely more research required into this. I can't say I hate the grain, but it's a bit much for 35mm and sometimes even when printing 645 to 11x14. I've been using fresh FP4+ recently and gotten a lot of grain. I might try shooting both an older and a newer roll and processing them at the same time to see if there is actually some perceptible difference there.

Also, for the EXG1 TEA solution in general, it's still the same color after months in a bottle, but it did build up a thin darker film in top of the solution. It all goes into solution the same way as usual and looks the same, but I wonder if this slight bit of oxidized glycin might cause the grain increase.

 

[grainyvision]

Unfortunately, I must give an update. "Forever" came today and my glycin-TEA mixture has went off in some way after 6 months in a half open bottle. If you decide to mix it, it likely will still be a very long life developer, but with more careful storage than I put into it. ie, decant it into smaller full bottles.

When the mixture is fresh, there is specific color changes of the solution that is expected:
* The stock solution is rather pinkish orange before introducing water, maybe yellow when very freshly mixed
* When adding the solution to water, if you can catch it, there is typically a color change to orange that only lasts briefly
* After mixed into the water after at most a minute, the solution should then change to a pale straw yellow with a hint of pink. This is the final color
* When adding the carbonate, the solution will turn a deep orange, sometimes even slightly brown
* After 30s or so, the solution should return to a the pale final color. The solution should remain close to this color even after development (assuming no antihalation dyes of course)

The stock solution I have now looks much darker in color, with a brown tint. When put into the water the solution turns a fairly deep orange and no further color change occurs. When adding the carbonate it turns a darker orange.

I haven't tested proper EXG1 with the stock since this occurred, but used the stock for a different (prototype) developer formula and the results came out unexpectedly under developed compared to a previous very similar formula using this solution.

I have a few ideas for potentially rectifying this such as the obvious addition of sulfite, using less TEA and adding glycol (unsure if this is possible due to solubility). I've had similar results with a hydroquinone-TEA mixture where the solution discolored, though for the purposes I used that for, it had no difference in effect. I think that despite TEA being "water free", that it is not as good of a preserving solvent as glycol. Glycol of course is of more acidic pH compared to TEA which also means any water that gets into the solution absolutely will cause developer decay quite quickly, whereas with an acidic or neutral pH solvent, the water would not cause instant decay. Alternatively of course, keeping the bottle full at all times limits water intake and likely would greatly extend the life of the solution.

 

[grainyvision]

Actually figured out the problem. Photographers Formulary sells an inferior grade of TEA. Specifically it seems they sell a grade which contains a significant amount of water impurity. I refrigerated an unopened bottle I recently purchased from them and even at 45F the solution did not freeze, indicating a significant amount of water in the solution. I'll probably try buying 99% from chemistrystore as well as the tech grade stuff from Art Craft and see how this formula behaves in both. I assume either way shelf life would be significantly improved, while the DEA/MEA impurity of tech grade could cause it to become a finer grain developer

 

[juan]

I’ve bought from the chemistry store for years without issue. Learned about it from Pat Gainer.

 

[grainyvision]

I've done some actual densitometry tests using "EXG1-2", a formula that should be identical to EXG1, but is made to hopefully be slightly more shelf-stable and a bit easier to use. Mixing instructions:

Part A: -- requires heating
* 80ml triethanolamine 99% low freeze grade (what I have, can be replaced by 85% TEA, 15% water)
* 10g glycin
* Top to 200ml with propylene glycol
* Add 0.1g or "a pinch" of sodium metabisulfite. It will mostly not dissolve. This should help to make use of what water is in solution to be more preserving
* Let settle and cool for 1 hour
* Pour into final container. Leave insoluble powder behind, but a little bit in the final container won't hurt anything. Do not shake container before use

Part B:
* 140ml water
* 60g potassium carbonate, anhydrous
* top to 200ml water

Usage: 40ml + 40ml to make 1L of working solution developer. Everything should be pretty much the same as EXG1 including color transitions.

For densitometer tests, I use 35mm FP4+ exposed using exposure setting number 5 on an X-rite 334 sensitometer. I then use an X-rite 331 densitometer for measurement. Neither piece of equipment has been properly calibrated or rather the calibration it had is expired. Absolute results thus should not be taken with too much confidence and so it's more interesting rather for comparison purposes. The test strip was developed in a hand tank for 10m30s, at 73F. 30s of initial agititation and then 4x agitation in ~8s every minute. Several water washes were used as a stop bath and 3 minutes in TF-4 was used for fixing. Final results were washed under running water for 2 minutes and then put into photo-flo solution. Each density was checked at least twice to account for noise and measurement error. All measurements I'd say are fairly confident within a few percent.

The dmin in D-76 1+1 was measured to be 0.31. The dmin in EXG1 was slightly more purple to the eye and measured 0.33. Using unexposed areas of previously processed films, the 0.33 minimum density seems to be consistent on FP4+ in EXG1 regardless of development time. I'm unsure why the dmin is different, maybe due to the lack of sulfite preventing the clearing of some dyes or something.

The graphs I've made are attached. One was made using absolute density and the other using density after subtracting the dmin of each developer. The results are quite telling. The speed index of EXG1 is actually slightly higher than D-76, indicating that it might be very slightly over developed. Obviously reading the charts though, EXG1 has much less shadow density and thus shadow gradation is much more steep, leading to a more "brilliant" result with shadows further away from highlights. Less highlight compensation seems to be evident in EXG1 when compared to D-76. This steeper shadow gradation may also be an effect that masks some of the grain perception.