Advice on my Two Bath Developer

[relistan]

Hey folks, I am a fan of two bath developers and have in the past used several versions of divided D-76, Barry Thornton's two bath developer, Diafine, etc. I have been working for the last few weeks on concocting a two bath developer to see if I can get something that is usable as a regular developer. Ideally I could use it like Diafine, where I just keep putting back the A and B into their respective stocks until it's time to throw it out. I want to retain full film speed. Diafine and divided D-76 negatives are a bit flat and I'd like a bit stronger contrast if I can manage it. I know everything is compromises.

I found and read 1980s era MSDS sheets for Diafine and read everything I could find about two bath developers (which are almost all MQ—except Diafine). The general theory is that for a two bath developer, substantially no development happens in the first bath and then development starts in the second. I know from experience with various 2 baths that that's just not reality. If you want full film speed, you always have and and need to have a little development in the first bath. The emulsion (at least modern emulsion) just doesn't soak up enough developer to develop only from what was absorbed. So, I decided to try a PQ developer, knowing that phenidone will start development even in mildly acidic solutions.

My thinking was that if I can keep the pH around 8 in bath A, then the phenidone can do some development there and the hydroquinone will really kick in when it hits a highly alkaline bath B. I needed to get the ratio of phenidone to hydroquinone right and wanted somewhat more activity given the split nature of the developer, so I modeled that ratio on ID-67 which would be diluted 1 + 2 for films, but I'm not diluting it. I was trying to keep sulfite to reasonable levels. I want enough to preserve the developing agents, and to act as a mild solvent without getting into a highly solvent scenario. Does the amount I used seem to straddle that? I split the sulfite into both baths to make sure that there is some solvent action for both parts of the development, and to make sure there is a bit of preservative in B.

I'm looking for some advice about things that I might need to think about that I haven't. I've got a developer that seems to work well, has lasted a couple of weeks in partially filled bottles, and retains full film speed. I've put a few rolls through it. It is not buffered at all in the A bath (unless... will sulfite and citric acid form an effective buffer?) and I wonder if that is likely to be an issue, for example.

Here's what I've got. I'll call it experiment 2B-1:

Bath A (1 liter)

• Water to 800ml @ 40C
  
• Sodium sulfite andhyrdous — 35g
• Hydroquinone — 8g
  
• Phenidone — 0.25g
• Potassium bromide — 1g
  
• Citric acid — 0.5g (to pH about 8 tested with paper strips)
• Water to 1L

Bath B (1 liter)

• Water to 800ml @ 40C
• Sodium sulfite anhydrous — 35g
• Sodium carbonate anhydrous — 20g (46g decahydrate crystals if I did math properly)
• pH is about 12
  
• Water to 1L

The phenidone was mixed from a propylene glycol solution to help with accuracy (1g phenidone into 40ml PG). So there is propylene glycol floating around in there as well. Mixed from Irish tap water, which at least in this part of Dublin seems to be very clean (straight down from the Wicklow mountains). It is fluoridated though.

So far I have tested it and arrived at the same times for Ilford FP4 and Fomapan 400 (5 mins A, 4 mins B). I know someone will ask about densities and H&D curves but I don't have a densitometer (yet...).

Looking for more general things like "you may need to think about X for longer shelf life" or "substitute X for Y and you'll get improved Z". I was specifically wondering about a developer you keep reusing but without a strong buffer. Reading data sheets, original Diafine seems to use a TSP/citric acid buffer a lot like organic chemists' https://en.wikipedia.org/wiki/McIlvaine_buffer . It also uses TSP mixed with carbonate as the accelerator in the second bath. I have some TSP. I was hoping to keep using citric acid but could switch to sodium metabisulfite.

I was thinking about tap water quality and tempted to add a tiny amount of EDTA (I have a ton of it). But Haist says that EDTA in the developer can actually accelerate oxidation of the developing agent if any iron ions are present.

I know it doesn't tell you that much without the negatives (some are drying, will photograph) but it does work well. Here's Fomapan 400 at EI200 (what I normally would use it at in XTOL)

 

[Donald Qualls]

Biggest thing for shelf life is using distilled water. This avoids unpredictable effects of unknown additives to municipal water supply (fluoride, almost certainly either chlorine or chloramine, possibly sodium silicate as a pipe preservative) as well as seasonal variations in pH that occur with some supplies. Beyond that, phenidone has a reputation of not keeping well in water solutions, but that doesn't seem to apply to Xtol stock solution, Diafine Bath A, and other mixed developers, so it may only mean you can't keep phenidone in a, say, 2% solution in water for ease of mixing (your 2.5% solution in glycol won't have this problem, as long as the glycol is anhydrous).

The general rule for "true" two-bath developers (in which little or no development takes place in Bath A due to pH) is that they use the same times for all films; this is because Bath A needs to be long enough for the developer to saturate the gelatin (and leaving it longer does no harm, but no good, either), and Bath B should be carried to exhaustion of the carried-over developer in the gelatin, hence again going longer does no harm, but gains (almost) nothing, either. In fact, your times are on the long side; Diafine instructions call for three minutes in each bath, and with thinner modern emulsions even that might be longer than needed (I haven't used Diafine since the early 2000s, though I still have a liter of it from that time -- need to test it to see if it's still good, can't go by eye because phenidone doesn't discolor when it goes off).

 

[Bill Burk]

Why not go back and forth between baths? Water rinse in between. Each dip in bath 1 picks up enough active developer to lift highlights a bit. Should still keep highlights from running away with density

 

[Bill Burk]

I was thinking that something like this happens to me when I develop several sheets in a tray of D-76 1:1. Only the sheet on top gets fresh developer. The rest of the sheets depend on what’s in the laminar layer between them. I get a little extra edge density which tells me it’s a real effect.

So why not go back and forth (with a rinse in between)?

 

[Alan Johnson]

Re: 2B-1
Emofin was a speed increasing 2-bath developer.Probably a lot of research went into it. There was some development in Part 1, I have tested it.
Bill Troop suggested a substitute, I have not tried it:
https://www.photrio.com/forum/threads/microdol-x-replacement.46346/page-8#post-669467
The PPD is probably just a solvent but it will give finer grain than 2B-1.
You have replaced Metol by PQ - effects not otherwise reported AFAIK, an experiment on Part 1.
Because Metol is slower acting than PQ I daresay Metol will bring up the shadows more, giving higher film speed than 2B-1

You have done the same as Bill Troop with Part 2, replaced the generally used Borax or Metaborate with the more alkaline Carbonate-Sulfite mix.
Research of Tetenal and Bill Troop is hard to beat. Quite likely 2B-1 will be more grainy and have lower film speed .

 

[relistan]

Biggest thing for shelf life is using distilled water. This avoids unpredictable effects of unknown additives to municipal water supply (fluoride, almost certainly either chlorine or chloramine, possibly sodium silicate as a pipe preservative) as well as seasonal variations in pH that occur with some supplies. Beyond that, phenidone has a reputation of not keeping well in water solutions, but that doesn't seem to apply to Xtol stock solution, Diafine Bath A, and other mixed developers, so it may only mean you can't keep phenidone in a, say, 2% solution in water for ease of mixing (your 2.5% solution in glycol won't have this problem, as long as the glycol is anhydrous).

Thanks, yeah, practical limitations guided that decision. Distilled water is basically impossible to buy here. I can get deionized, but have to get it from the auto parts store and being in 5km radius lockdown, can't get to the auto parts store right now—so I figured tap water would be worth a shot. I guess I'll see how it lasts and if it's not long, go back to deionized water when I can get it. In theory I have a source of distilled water in my laundry dryer, but it's impossible to get it without any mold spores or spots in it, which means essentially harvesting it from the dryer, boiling it, and then filtering. Ugh.

The general rule for "true" two-bath developers (in which little or no development takes place in Bath A due to pH) is that they use the same times for all films; this is because Bath A needs to be long enough for the developer to saturate the gelatin (and leaving it longer does no harm, but no good, either), and Bath B should be carried to exhaustion of the carried-over developer in the gelatin, hence again going longer does no harm, but gains (almost) nothing, either.

Thanks, yes, as I mentioned I have a lot of experience with using various two baths and that doesn't really work like that, with modern thin emulsions anyway. You get very thin or very flat negatives unless a little development happens in A. Barry Thornton's two bath (a kind of split D-23) does some development in the first bath. Also from what I read, a PQ developer is not going to work that way unless you get the pH down below 6, which I obviously don't want to do with a high pH second bath. Even Diafine bath A develops film, albeit even more slowly than my experiment does. I never left it in there for long enough to see what it eventually does.

In fact, your times are on the long side; Diafine instructions call for three minutes in each bath, and with thinner modern emulsions even that might be longer than needed (I haven't used Diafine since the early 2000s, though I still have a liter of it from that time -- need to test it to see if it's still good, can't go by eye because phenidone doesn't discolor when it goes off).

My regular times with Diafine were 4 and 4. I used it off and on for a decade, ending about 2 years ago when the price went nuts for the second time. 4 and 4 works in this developer, too, but I think the negatives are on the thinner side. Lacking a densitometer, I can't say for sure what the density difference is but an extra minute in A seems to help. I have not tried anything other than the two films I mentioned, though, so who knows? Maybe Tri-X works with 3 and 3. If you have your Diafine still mixed up and would be willing to do a pH test on Bath A I'd be super appreciative. I read that it was 8.25 but not from a reliable source.

That all said, I'm not really trying to replicate Diafine. I'm trying to get the things I liked from it and other two baths and maybe "improve" it (defined as making it more like I'd like it to be).

Side note: doesn't phenidone turn orange (not brown) when oxidized? I have definitely seen my PC-Glycol slowly turn orange, but maybe that's the ascorbic acid. I think I once mixed a phenidone developer with phenidone first (before the hydroquinone) and it turned orange (pink?) until the Q was added.

So why not go back and forth (with a rinse in between)?

Hey, it's worth trying! If once through both works, then I'll just keep doing that, but your idea could lead to some interesting formulations.

 

[relistan]

Re: 2B-1
Emofin was a speed increasing 2-bath developer.Probably a lot of research went into it. There was some development in Part 1, I have tested it.
Bill Troop suggested a substitute, I have not tried it:
https://www.photrio.com/forum/threads/microdol-x-replacement.46346/page-8#post-669467
The PPD is probably just a solvent but it will give finer grain than 2B-1.
You have replaced Metol by PQ - effects not otherwise reported AFAIK, an experiment on Part 1.
Because Metol is slower acting than PQ I daresay Metol will bring up the shadows more, giving higher film speed than 2B-1

You have done the same as Bill Troop with Part 2, replaced the generally used Borax or Metaborate with the more alkaline Carbonate-Sulfite mix.
Research of Tetenal and Bill Troop is hard to beat. Quite likely 2B-1 will be more grainy and have lower film speed .

Thanks! This is interesting, I will take a look. I appreciate the thoughtful analysis and the link!

 

[relistan]

Here are some negatives on the light table and some scans from them. This is Ilford FP4+ (5 mins A, 4 mins B) shot in my Yashica Electro 35 GSN. The scans were done together to make sure contrast is matched. The only adjustment on the photo of the light table is that I adjusted the white point to the background. Just test roll shots, no artistry involved!

100% crop at 2400 dpi from center of EI 125 shot (thumbnailed)

 

[Alan Johnson]

It's not very clear if you are reporting a increase in film speed vs D-76.
I have used pics of a sun/shade scene exposed at 1/3 stop intervals, multiple sets of 6 on the same film, developed in D-76 and in the test developer to get a better estimate.

 

[relistan]

It's not very clear if you are reporting a increase in film speed vs D-76.
I have used pics of a sun/shade scene exposed at 1/3 stop intervals, multiple sets of 6 on the same film, developed in D-76 and in the test developer to get a better estimate.

Oh sorry, no I was not reporting anything about speed increase. I was just showing part of the exposure test I did on FP4 as an example. Doing a comparison to D-76 is a good idea. I'm sadly saddled with atrocious weather at the moment (ice storm, constant high winds for a few days) so the best testing I have been able to do has been indoors. From that testing and shots in daylight through windows, it appears to work fine at box speed for FP4 and at EI200 for Fomapan 400, which is what I have usually shot it at. I will do some sunlit outdoor testing on the first day that is possible.

• I doubt the pH of Diafine A is alkaline. I suspect neutral (possibly slightly acidic)

I would have thought so, too, but just reporting the only source I found. If someone has some and can measure it that would be really informative.

• A non-alkaline pH for bath A is part of what gives "true" two-bath developers long shelf lives.

Good to know. Thanks.

• When using a combination of developing agents which is strongly superadditive (such as PQ), remember that activity is > than the sum of the parts, so you can't treat the two compounds as separate entities when considering the pH of the solution. In other words, you can't say that at a pH of 8 you get some Phenidone activity without HQ activity. Quick example - Ilford DD-X is a general purpose PQ developer with a working pH of approx. 8.5

Sorry I was not explaining clearly enough. You are right to point that out. Please correct any of the following if I've got it wrong. Here was what I was thinking, from my understanding: below the active pH for hydroquinone its only role is really to regenerate the phenidone. So in the bath A, that's what it is doing and phenidone is the primary developing agent. However, in bath B, with the pH of 12, the hydroquinone can itself also become active as a developing agent, providing higher contrast for the period of development that it is active (in bath B). I was thinking about Hans Dietrich's D-76-based reversal developer where he adds carbonate to get the pH up high enough to activate the hydroquinone as a primary developing agent. I think I read something about this in Anchell and Troop's Film Development Cookbook ages ago also.

• For some amount of increased contrast, try increasing HQ

That matches how I thought it worked. Thanks. That's what I was trying to do by using the same ratio as ID-67 but undiluted. Other developers use a fair bit less. The formula I've seen going around as a "Diafine-like developer" has 0.2g phenidone and 5g hydroquinone vs. 2B-1's 0.25g and 8g respectively.

• With a highly alkaline bath B (carbonate), watch for elevated base fog, especially if you use multiple cycles. Part of testing in formulating a developer is maximizing emulsion speed while minimizing fog, so some balancing/optimization of bromide might be necessary. The luxury one has with a true two-bath developer is the option of repeated cycles to max out emulsion speed (although in general both true two-bath and divided developers give high emulsion speed anyway), so all things being equal I would try to keep fog as low as possible

Thanks for the pointer. I have got very low fog with the current amount of bromide and with the development times I'm using. Again, no densitometer, so I'm eyeballing it compared to other films I've developed in other developers. I tried leaving film in bath B for a few more minutes and fog starts to rise noticeably as you say, after about 6 minutes. Bath A times beyond about 6.5 minutes also start to fog.

 

[relistan]

Here is the chart I was referring to earlier regarding pH for certain developing agents to become active. They won't achieve anything useful at that pH according to Haist, but will begin to develop the latent image. This of course is ignoring superadditivity effects.

My limited understanding is that at the reasonably high concentration of phenidone tested here is likely to account for some of that, and a lower concentration may not do much at that pH. Not sure if that's right, though. Certainly at about pH 8 2B-1's bath A produces images, albeit somewhat slowly.

 

[grain elevator]

Good stuff!
If modern films have too thin emulsion to hold enough developing agents for what you call "true" two bath developers, wouldn't the solution be increasing the concentration of said developing agents in bath 1?
Has anyone here tried something similar with ascorbate instead of HQ? I've read that it doesn't work because acidic byproducts inhibit development, just curious if anyone here has put that to the test.

 

[relistan]

Basically I would just suggest testing bath A on its own to see what it does, as part of optimizing 2B-1. You can decide if you want development to proceed in bath A or not.

Excellent suggestion, point taken. Thanks!

On the other hand, keep in mind I’m only making comments from a theoretical perspective. I’m not suggesting you should go down any rabbit holes or that you need to change anything about 2B-1. Ultimately what matters is whether or not you are happy with the negatives. If the negatives look good, you’re ok.

Thanks I do appreciate you saying that. Essentially I'm trying to accomplish something but also to learn, so the feedback you've given is exactly the kind of thing I was looking for.

Good stuff!

Thanks!

If modern films have too thin emulsion to hold enough developing agents for what you call "true" two bath developers, wouldn't the solution be increasing the concentration of said developing agents in bath 1?
Has anyone here tried something similar with ascorbate instead of HQ? I've read that it doesn't work because acidic byproducts inhibit development, just curious if anyone here has put that to the test.

Others, starting with @Bill Burk, have suggested just running the film through the baths more than once, which is a really good idea. That overcomes the inability to soak up enough developer. Of course it comes at the expense of wash time and multiple times through the baths. If I were a sheet film person I think that's what I would do.

I have not seen anything two bath based on PC in my searches. While I'm not anywhere near as knowledgeable as some of the folks on here, I have a hard time believing it wouldn't work. I believe that Phenidone also builds up acid byproducts while developing, for example. Maybe all or many other developers do, too. This is one reason you need an alkaline solution to effect reasonable development from what I read in Haist.

Patrick Gainer showed pretty well that you don't need and really get no benefit from having any sodium sulfite in a PC developer, so you would have something that looks completely different vs 2B-1 where the sulfite is providing both some solvent action and is the main accelerator in the A bath. Given what was said above, it might be interesting to try XTOL for e.g. 5 minutes as the bath A and a highly alkaline bath B with carbonate for example. You would get worse grain than XTOL I am sure, but would maybe achieve a compensating effect that might be interesting.

Starting from Gainer's PC-Glycol you could make up a bath A with e.g. borax and boric acid to get a neutral pH where you want it as another option.

 

[grain elevator]

A PC version of 2B-1 would work similarly to the PQ version. The difficulty lies more in getting longevity out of part A when ascorbate is involved.

Virtually any developer can be followed with an alkaline (or even plain water) second bath to increase overall density. However obviously this will change image structure characteristics, and will increase fog density. These things will depend on how alkaline the second bath is.

I'll try making a PC version eventually - I have HQ but I want to reserve it for lith developer, I prefer C for film as it's environment friendly, cheap and doesn't leave residues.
Regarding longevity, I hope using demineralised water would solve the Fenton reaction issue, as there would be no sulfite which I read can also introduce traces of metal ions. Remains the question of which alkali to bring it to a neutral pH - I have TEA, Kodalk, washing soda, drain cleaner NaOH pellets and baking soda at hand. Any guesses which might be best regarding freedom from metal impurities? Or do you reckon there's a chance it could work with acidic (ascorbic acid, no alkali) first bath, which should be very beneficial for longevity? I'd try to prevent mold with a bit of isopropanol. Sound good?

 

[relistan]

I'll try making a PC version eventually - I have HQ but I want to reserve it for lith developer, I prefer C for film as it's environment friendly, cheap and doesn't leave residues.
Regarding longevity, I hope using demineralised water would solve the Fenton reaction issue, as there would be no sulfite which I read can also introduce traces of metal ions. Remains the question of which alkali to bring it to a neutral pH - I have TEA, Kodalk, washing soda, drain cleaner NaOH pellets and baking soda at hand. Any guesses which might be best regarding freedom from metal impurities? Or do you reckon there's a chance it could work with acidic (ascorbic acid, no alkali) first bath, which should be very beneficial for longevity? I'd try to prevent mold with a bit of isopropanol. Sound good?

You can make an acid first bath for sure. But you won't want it to be very strongly acidic. If it is, you'll get unpleasant results when the alkali are introduced in the second bath. I don't think it matters much which alkali you use to neutralize the ascorbic acid. It would if solubility or compatibility with other ingredients were important. But all of those would be fine I think. You will need pH test strips to measure with and to add a little at a time until you reach your target pH. I tried to figure out how to calculate that recently and it was suggested by people who do actual chemistry in labs that this was a complicated thing to try to calculate and titration would be the best way to do it. I don't know how much mold prevention isopropanol will do. Getting some silver into the solution by using it a few times shortly after making it is probably the best way. Someone can correct me if I'm wrong about that.

 

[relistan]

Regarding the earlier conversation about first bath pH, I still had a batch of Anchell and Troop's take on Vestal's version of divided D-76. I measured the pH of the first bath last night and it's about 8 also, maybe a tiny bit less.

 

[grain elevator]

I'm not sure what the mold concern is.

If you have any worries regarding CO2 formation, stick with borate alkali.

I think if the goal is to have a bath A with a long shelf life, this would be difficult to achieve with ascorbate in an aqueous solution. An additional potential complication with preservation of ascorbate is that the dreaded Fenton reaction is increasingly problematic under acidic conditions, so some balance needs to be struck around a neutral pH.

For anyone tinkering with developers I suggest a pH meter rather than strips.

Would a AA and Phenidone solution not be susceptible to mold?
Thanks for setting me straight on the effect of PH on the Fenton reaction, I had it backwards. Then of course neutral or slightly basic pH makes sense. My question what alkali would be best for that was with an eye to the Fenton reaction - as there wouldn't be any need for sulfite in a PC first bath, if using demin water, the alkali would be the most likely culprit to introduce iron ions as impurites, so perhaps there is an alkali which typically doesn't contain them - I know nothing about the refining processes of these substances, but maybe someone here does.

 

[Alan Johnson]

Relayer had a PC 2 bath, IIRC the negatives were a bit thin compared with BTTB:
https://www.photrio.com/forum/threads/diafine-revisited-ascorbate-version.78123/

 

[relistan]

Regarding my 2B-1 experiment:
I shot some more realistic outdoor mixed light shots on ADOX Silvermax, but forgot that was what was loaded in the camera. Thinking it was Fomapan 400 I shot it at EI200. Results were OK! Not up to the standard I would say of my favorite developer for Silvermax, but I am fairly happy with the result for a first try developer. Here's one frame in 2B-1 for 5 mins A, 4 mins B. The weird thing on the left is because it was the first shot on the roll and was very partially exposed on the edge. Sharpness seems good, grain a little pronounced but not heavy.

If anything they are maybe a little overdeveloped. I will try to lower the pH of bath A and see how that goes.

 

[relistan]

Looks good!

Thank you! I'm happy with this

 

[relistan]

Update: I lowered the pH of bath A to 7 using citric acid. After that, testing showed that no real development was happening in bath A at all. However, using the same dev times, resulting negatives were too thin as I had thought might happen. I bumped it back up to 8 with sodium hydroxide and things are working fine again.

 

[john_s]

Although we can consume citric acid, it's actually quite a strong acid. Since the point of true two bath development is to use the developer absorbed in the emulsion from Bath_A, maybe the citric acid also absorbed is messing it up. I think usually if a Bath_A is to be low enough pH to not develop in its own something like metabisulphite is used which might be more compatible with the process.
What's the appeal of having absolutely no development in Part_A, rather than something like a mild developer followed by an alkaline bath, like BTTB?

 

[Maris]

Thanks, yeah, practical limitations guided that decision. Distilled water is basically impossible to buy here....

An old trick but a slow one is to use OXYGEN FREE water for mixing mild reducing agents that include photographic developers.
I boil a full jug of water in the evening to drive out dissolved gases and by the morning it is cold and ready to use. Then pouring it slow and smooth into the mixing vessel so as not to entrain air I add the ingredients and slowly agitate with a PLUNGER type mixer not a stirrer. I've had Xtol last two years in a full, no air-space bottle, using this procedure.

 

[john_s]

Historically there were essentially three significant things about having no/almost no activity in bath A. 1) You can keep reusing it, so it is economical. 2) It more or less eliminates time as an element of control, so it is somewhat “automatic”. 3) Longevity/shelf life.

Thank you for the clear explanation.

 

[relistan]

Although we can consume citric acid, it's actually quite a strong acid. Since the point of true two bath development is to use the developer absorbed in the emulsion from Bath_A, maybe the citric acid also absorbed is messing it up. I think usually if a Bath_A is to be low enough pH to not develop in its own something like metabisulphite is used which might be more compatible with the process.

Citric acid is a strong acid, but in this case I believe that only the pH that matters. I added just 2g of citric acid and then later countered it with a minute amount of NaOH. I think the more likely negative outcomes of too much citric acid might be the formation of some silver citrate from silver dissolved by the sulfite. That would lead to fogging if the amount of sulfite isn't enough to keep it soluble.

What's the appeal of having absolutely no development in Part_A, rather than something like a mild developer followed by an alkaline bath, like BTTB?

I think @michael_r did a good job explaining. I think the main thing would be that the amount of time in the baths makes no difference at all. The first bath just soaks up developer and the second bath exhausts and then does nothing. I'm OK with a more divided developer vs full two bath solution if it gets what I wanted. It would be nice to get it to do less development in bath A than it is doing. I think it might take an even stronger alkali in the bath B, though to get enough to happen. That's at least my experience so far. Diafine traditionally used trisodium phosphate and that might be worth a try (I have some).

An old trick but a slow one is to use OXYGEN FREE water for mixing mild reducing agents that include photographic developers.
I boil a full jug of water in the evening to drive out dissolved gases and by the morning it is cold and ready to use. Then pouring it slow and smooth into the mixing vessel so as not to entrain air I add the ingredients and slowly agitate with a PLUNGER type mixer not a stirrer. I've had Xtol last two years in a full, no air-space bottle, using this procedure.

Not a bad idea. I always try hard to pour the developer without introducing much bubbling, but intentionally removing oxygen up front is a good idea.

 

[relistan]

Well, after doing a bunch of test clips from rolls and verifying the behavior of Silvermax 100 at box speed, I decided I had enough confidence to risk some holiday shots from 2019 with this developer. I really could not be happier with how these came out. Here's one.

Leica M2, Leica Summarit-M 2.5/35mm on ADOX Silvermax 100 at box speed in 2B-1 for 4 mins A, 4 mins B @ 18C. Carcassonne, France, July 2019.

I'll keep experimenting, but this is a totally usable developer with most of the characteristics I had set out to achieve. I don't know what shelf life or capacity are like. The grain seems to be finer than the resolution of my scanner at 3200dpi. I'll have to stick a negative on the enlarger to get a better idea of how it looks compared to another developer like XTOL.