Why not 2 baths developer only?

BHuij · Monday at 1:36 PM

When I played around with Barry Thornton's 2-Bath (BTTB), chasing exactly the advantages cited by the OP (highlight compensation, increased acutance, better film speed), I found myself disappointed. Some of the negatives came out looking fine. Most came out a fair bit grainier than I prefer, particularly in 35mm where that really matters to me. Many of them suffered from uneven development due to the minimal agitation recommended. None of them showed even a hint of improved acutance to my eye.

Barry Thornton himself eventually moved on from BTTB and settled on a pyro-based developer he worked up himself calle DiXactol, and a few variants thereof. When I concluded that BTTB wasn't my cup of tea, I had the advantage of internet access and numerous recipes (and rave reviews) for pyro-based developers. After some research, Pyrocat HD seemed like the one to go with. I mixed up a batch and tried it on FP4+ in 120 and absolutely loved it right away. It does a tremendous job of compensating in highlights and giving excellent shadow separation and acutance that I think really make the final prints stand out compared to developers I've used in the past for the format (primarily Rodinal and HC-110), and it does so with somewhat less grain (and less harsh/unpleasant character to the grain IMO) than Rodinal.

At the time of writing this comment, I've standardized on 3 films across 3 formats, and each one has a preferred developer or two that I've arrived at after a lot of experimenting and testing. BTTB just doesn't fit in here, and none of the purported advantages of other 2-bath developers are compelling enough to make me experiment with them at this time. Maybe that will change. I go through phases of enthusiastically trying out new stuff in the darkroom just for the enjoyment of tinkering. But right now I'm very much in a "try to get better at art" phase, and frankly that is probably the more fruitful way to elevate my results

Film	35mm Preferred Developer	120 Preferred Developer	4x5 Preferred Developer
Delta 100	Instant Mytol	Instant Mytol or Pyrocat HD(C)	N/A (I don't use Delta 100 in LF)
FP4+	Instant Mytol	Pyrocat HD(C)	Rodinal or Pyrocat HD(C)
HP5+	Instant Mytol	Instant Mytol or Pyrocat HD(C)	HC-110 or Pyrocat HD(C)

Milpool · Monday at 1:49 PM

People attribute all sorts of imagined tone reproduction characteristics to developers and processing techniques.

Another problem - "compensation" isn't strictly defined. Based on discussions with some photographers it seems the goal (whether it happens or not is another matter) is basically highlight compression. Two-solution development gives a more linear characteristic curve, though the effect is relatively minor. People likely wouldn't notice a difference if they didn't know they were doing something different.

Lachlan Young said:
I think the thing that really comprehensively knocked two-bath development on the head was the discovery of development inhibition effects in their various forms. At a stroke it enabled better highlight control, and a much better speed/ grain/ sharpness relationship in a manner that allowed consistency at scale, rather than the sensitometrically vague guesstimates of various developer influencers in the popular press of the day. The thing that never ceases to amuse me is people who simultaneously spend their time muttering about why they don't like XP2 Super (at least when developed properly in C-41), yet spend dozens of pages declaiming about how their concoctions dredged and regurgitated from popular magazines of the mid-20th century produce compensating effects, without realising that unless the characteristic curve of their efforts matches XP2's, it ain't a compensating developer...

bluechromis · Monday at 2:45 PM

Lachlan Young said:
I think the thing that really comprehensively knocked two-bath development on the head was the discovery of development inhibition effects in their various forms. At a stroke it enabled better highlight control, and a much better speed/ grain/ sharpness relationship in a manner that allowed consistency at scale, rather than the sensitometrically vague guesstimates of various developer influencers in the popular press of the day. The thing that never ceases to amuse me is people who simultaneously spend their time muttering about why they don't like XP2 Super (at least when developed properly in C-41), yet spend dozens of pages declaiming about how their concoctions dredged and regurgitated from popular magazines of the mid-20th century produce compensating effects, without realising that unless the characteristic curve of their efforts matches XP2's, it ain't a compensating developer...

It's a little unclear to me what you are referring to with highlight control. Is this like the use of high dilutions and long development times that cause local developer exhaustion in highlight areas?

DREW WILEY · Monday at 2:47 PM

I thought the Russians shot down the XP2 long ago when Gary Powers was flying it. I sure haven't paid any attention to C41 b&w film since that era, and am quite surprised to see it referenced in relation to two-bath development.

bluechromis · Monday at 3:22 PM

halfaman said:
D-76H is Haist effort to probe that only one developing agent is needed to formulate a developer, an idea he was an advocate of according to PE. It is at best nor better neither worse than Kodak official D-76, besides a probable shorter shelf life.

My understanding is that a major goal with D-76H was to mitigate pH instability when storing the stock solution. From what I have read, Haist succeeded in that. There are other improved versions as well. If D-76H maintains a stable pH does that not imply that the shelf life in a consistent form would be greater?

It is true that a home mixed D-76 is not going to have all the features of a packaged, commercial version. Kodak jumped through hoops to put all the ingredients in one bag without some components degrading the others. (Ilford's two-bag approach might have advantages.) There are probably sequestering agents in commercial D-76 formulations. But do those packaging features matter that much to a home user who is using clean water?

Sidd · Monday at 3:26 PM

BHuij said:
When I played around with Barry Thornton's 2-Bath (BTTB), chasing exactly the advantages cited by the OP (highlight compensation, increased acutance, better film speed), I found myself disappointed. Some of the negatives came out looking fine. Most came out a fair bit grainier than I prefer, particularly in 35mm where that really matters to me. Many of them suffered from uneven development due to the minimal agitation recommended. None of them showed even a hint of improved acutance to my eye.

Barry Thornton himself eventually moved on from BTTB and settled on a pyro-based developer he worked up himself calle DiXactol, and a few variants thereof. When I concluded that BTTB wasn't my cup of tea, I had the advantage of internet access and numerous recipes (and rave reviews) for pyro-based developers. After some research, Pyrocat HD seemed like the one to go with. I mixed up a batch and tried it on FP4+ in 120 and absolutely loved it right away. It does a tremendous job of compensating in highlights and giving excellent shadow separation and acutance that I think really make the final prints stand out compared to developers I've used in the past for the format (primarily Rodinal and HC-110), and it does so with somewhat less grain (and less harsh/unpleasant character to the grain IMO) than Rodinal.

At the time of writing this comment, I've standardized on 3 films across 3 formats, and each one has a preferred developer or two that I've arrived at after a lot of experimenting and testing. BTTB just doesn't fit in here, and none of the purported advantages of other 2-bath developers are compelling enough to make me experiment with them at this time. Maybe that will change. I go through phases of enthusiastically trying out new stuff in the darkroom just for the enjoyment of tinkering. But right now I'm very much in a "try to get better at art" phase, and frankly that is probably the more fruitful way to elevate my results

Film 35mm Preferred Developer 120 Preferred Developer 4x5 Preferred Developer

Delta 100 Instant Mytol Instant Mytol or Pyrocat HD(C) N/A (I don't use Delta 100 in LF)

FP4+ Instant Mytol Pyrocat HD(C) Rodinal or Pyrocat HD(C)

HP5+ Instant Mytol Instant Mytol or Pyrocat HD(C) HC-110 or Pyrocat HD(C)

Sandy King in an email told me he developed Pyrocat HDC keeping in mind stand development. I haven't tried it till now, certainly will do. Also I asked him regarding 2 bath development using Pyrocat-MC, he answered that he never tried it, but will probably work good. That is also one of my pending projects.

DREW WILEY · Monday at 3:31 PM

I have tried Formulary's version of buffered D76. I don't think it adds anything to storage or tray life. It just prevents the typical pH shift which occurs between freshly mixed D76 and when it reaches it plateau of equilibrium about a week later.

Sidd · Monday at 3:39 PM

bluechromis said:
My understanding is that a major goal with D-76H was to mitigate pH instability when storing the stock solution. From what I have read, Haist succeeded in that. There are other improved versions as well. If D-76H maintains a stable pH does that not imply that the shelf life in a consistent form would be greater?

It is true that a home mixed D-76 is not going to have all the features of a packaged, commercial version. Kodak jumped through hoops to put all the ingredients in one bag without some components degrading the others. (Ilford's two-bag approach might have advantages.) There are probably sequestering agents in commercial D-76 formulations. But do those packaging features matter that much to a home user who is using clean water?

Anchell tells in Darkroom Cook Book that many photographers feel that D-76 mixed as per standard formula is better than the packaged commercial one.

retina_restoration · Monday at 3:50 PM

Sidd said:
Coincidentally I have also prepared some of Karl's 2B-1 yesterday, and developed a roll. However, I've followed Karl's instructions and recipe faithfully. Scrutiny of the negative tells me the development was good, although I haven't been able to scan those. Hopefully, tonight or tomorrow I'll be able to.

@retina_restoration your FP4 images are striking!

Thank you.

Keith Tapscott. · Monday at 4:10 PM

I prefer single solution developers myself, but this may be of interest.

HMECINE

bluechromis · Monday at 4:27 PM

When people complain that two-bath developers and phenidone-based developers like Xtol lack contrast, I wonder if it isn't a case of one person's bug is another person's feature. The way that those developers are easy on highlights could be perceived as a lack of contrast by some. (Though I have seen Xtol images developed such that they have as much contrast as one would want.) But other people appreciate that those developers are less inclined to blow out highlights.

I wonder if the reason that Diafine recommends higher E.I.s is because if the film were exposed at box speed, it would look pretty flat. Maybe this is similar to the situation with Delta 3200, where the actual ISO may be around 1000. Improved shadow detail would be available at 1000 ISO. But some people say that it looks too flat at that speed and needs a higher E.I. to get punchy contrast.

halfaman · Monday at 4:36 PM

bluechromis said:
My understanding is that a major goal with D-76H was to mitigate pH instability when storing the stock solution. From what I have read, Haist succeeded in that. There are other improved versions as well. If D-76H maintains a stable pH does that not imply that the shelf life in a consistent form would be greater?

It is true that a home mixed D-76 is not going to have all the features of a packaged, commercial version. Kodak jumped through hoops to put all the ingredients in one bag without some components degrading the others. (Ilford's two-bag approach might have advantages.) There are probably sequestering agents in commercial D-76 formulations. But do those packaging features matter that much to a home user who is using clean water?

ph fluctuations after mixing are common to any developer containing hydroquinone, but it stabilizes after a few hours. If you remove HQ (D-76H), then the fluctuations are solved. You can also put a buffer, like borax/boric acid, to stabilize it from the very beggining. Or just wait overnight before use, like it was recommended for home cooking.

Kodal D-76 exact composition is unknown and for sure it has many tweaks to make it the best possible version of the original recipe. And it is one of the reason (lazyness the main one) why I have never formulated D-76.

Rod Klukas · Monday at 4:54 PM

Just to throw another recipe at you for D23. If you have extreme contrast to create, we were able to do a plus 4-5 stops on our film using D23 and DK25 replenisher.

First make your gallon of D23. Now make a Gallon of DK25 replenisher. Brown Glass bottles are best. And keep in a dark cupboard.

On the D23 bottle using a sharpie mark the liquid level. You are ready for a lot of film. I had mine for 12 years before I broke the D23 jug accidentally.

So develop using the D23, but do not discard. Pour it back in its bottle. After finishing look at the D23 jug. If the level is below the line, add DK25 until it is back to the line.

Over time you will have a silver sludge in the bottom which makes it better.

Just keep level up to the line.

It can build contrast easily on flat scenes but times are long. I had some that created +4-5 stops.

I learned this from Oliver Gagliani, who got it from Ansel, who may have got it from Paul Strand. Look at Strand's images of ferns and grass from Nova Scotia, and the Gaspe. The burnished look

of some of his leaves came from D23 at times. I was an assistant to Oliver for 5 years in the 1980's and friends until his passing.

A look at Oliver's work, will find some great minus work as well using D23. 4-6 hour development times with water bath. Exposures were up to 6 hours as well.

It, as others have noted, the older thick emulsions are better for these times and developers, than the Tgrain types.

Be well,

Rod

retina_restoration · Monday at 5:01 PM

Keith Tapscott. said:
I prefer single solution developers myself, but this may be of interest.

HMECINE

Thanks for that, it looks like another variation on the theme, and worth trying.

Vetus · Wednesday at 6:27 AM

DREW WILEY said:
I did side by side testing with Ilford packaged Perceptol and my home brew - precisely the same results. There's nothing particularly secret about it. There might be some kind of added preservative or something like that in the factory packs, but it's otherwise a basic simple MQ sodium sulfite developer plus the "secret ingredient" of sodium chloride, which they openly list ... not typical table salt, which has added things like iodine and titanium dioxide.

I can't contribute anything to the Microdol debate; but I know there are others on this forum who have home-brewed their own of that in the past; and if they choose to chime in, that's up to them.

Have you ever tested if table salt, kosher salt or no salt makes a noticeable difference?

DREW WILEY · Wednesday at 11:27 AM

I'm sure others have done those sorts of "tests" long before me. It was an Ilford chemist who first divulged the formula. Iodine would be an obvious troublesome ingredient. And titanium dioxide is a white pigment commonly added to table salt, also used in toothpaste, sunburn cream, and many types of paint, etc. Doesn't make any sense to introduce a pigment into the brew which might not fully dissolve.

Kosher salt is just a cheaper option for salt which hasn't been artificially adulterated. I'm not going to get into Himalayan pink salt, or salt from the Bonneville Speedway on Great Salt Lake, or lithium inflected salt from Lake Titicaca, or which works best on grilled salmon, or whether you should throw it over your right shoulder or left before adding it. Official sodium chloride doesn't cost much anyway, compared to most developer ingredients.

DREW WILEY · Wednesday at 11:37 AM

Rod - interesting that you worked with Oliver G. I didn't know him, except to encounter him once teaching a workshop, with all of them sitting among wildflowers out at Pt. Reyes, actually, Tomales Pt not far from the barns with their cobwebbed windows. That was sometime in the 90's, I believe.

Some interesting alchemy.

relistan · Thursday at 11:53 AM

retina_restoration said:
Back to Divided (2 bath) Developers...

Yesterday I decided to revisit Karl Matthias's divided 2B-1 developer — with 2 developing agents in it: Hydroquinone and Phenidone. In pervious tests with 2B-1, I found it too active for my liking (still developed highlights more than I wanted) so yesterday I tweaked the recipe a bit by decreasing the amount of of Hydroquinone from 8 grams per liter, to 5 grams per liter and reduced the Phenidone from 0.25 grams per liter to just 0.20. I kept the 4.5 + 4.5 minutes development time, and my agitation protocol was 30 seconds in bath A to start, and then four inversions per minute to completion. In bath B I agitated for the first 10 seconds and then two slow inversions per minute afterwards.

My assessment is that the decrease of the amount of developing agents resulted in a more balanced negative, with less development of the highest values without decreasing the overall density of the negatives. FP4+ gave me good negs at 100 ASA but I preferred the negs that received at least 1/2 stop more exposure in the case of my test subject (very deep shadows). FP4+ behaved beautifully in this developer and gave me a brand range of subtle/tactile values with excellent tonal separation. Sharpness and acutance is very good and grain characteristics are typical for FP4+: smooth and moderate.

Example image here. Second example here.

I also exposed a roll of Adox CHS 100 II (at 50 ASA) and developed it exactly the same, and the results were also quite nice, but the Adox film still leans toward excess contrast IMO. Perhaps shortening the time in the first bath would help with that, I don't know. I still found CHS 100 II had to have at least one stop more exposure than its ASA rating suggests, but it did better in this modified 2B-1 than in some other developers. Example image here.

Fantastic results there, Paul (as usual!). In all the work I did with two baths, including Diafine which I used for years, the idea of the same time for all films certainly doesn't mean you get the best results for all films at all exposures with the same time. But you will almost always get a printable negative, which certainly has its advantages. In my own testing with 2B-1 I used slightly different times for some films. I found that ADOX Silvermax 100 actually responded so well that I regularly under-exposed it by a full stop.

I'm interested to see if you keep using this modified version of 2B-1. If you find that you like it, I may include it in a follow up post on my two posted developers a few years in (credited, of course). Others have contributed a lot interesting info and testing on PC-512 Borax and if you're willing, I'd include your modified version of 2B-1 if it pans out. Let me know.

Sidd · Thursday at 2:47 PM

relistan said:
Fantastic results there, Paul (as usual!). In all the work I did with two baths, including Diafine which I used for years, the idea of the same time for all films certainly doesn't mean you get the best results for all films at all exposures with the same time. But you will almost always get a printable negative, which certainly has its advantages. In my own testing with 2B-1 I used slightly different times for some films. I found that ADOX Silvermax 100 actually responded so well that I regularly under-exposed it by a full stop.

I'm interested to see if you keep using this modified version of 2B-1. If you find that you like it, I may include it in a follow up post on my two posted developers a few years in (credited, of course). Others have contributed a lot interesting info and testing on PC-512 Borax and if you're willing, I'd include your modified version of 2B-1 if it pans out. Let me know.

Karl, can you please tell me what is the longevity of a partially used 2B-1 solutions set? And, how many rolls can be processed in a preparation of 1 litre (×2)?

dcy · Thursday at 2:55 PM

@relistan: I read your blog post about 2B-1 with great interest. Could you tell me a little bit about what you like about 2B-1 compared to Barry Thornton's Two Bath? What does it do differently?

relistan said:
I'm interested to see if you keep using this modified version of 2B-1. If you find that you like it, I may include it in a follow up post on my two posted developers a few years in (credited, of course). Others have contributed a lot interesting info and testing on PC-512 Borax and if you're willing, I'd include your modified version of 2B-1 if it pans out. Let me know.

Oh! PC-512 looks interesting. I'm going to read that thread. I'm sure I'll have a question about it soon.

pentaxuser · Thursday at 2:56 PM

DREW WILEY said:
I'm sure others have done those sorts of "tests" long before me. It was an Ilford chemist who first divulged the formula.

Was he the one that was tried and jailed along with Gary Powers in the XP2 incident ?

pentaxuser

Lachlan Young · Thursday at 6:28 PM

retina_restoration said:
5 grams per liter and reduced the Phenidone from 0.25 grams per liter to just 0.20.

retina_restoration said:
decrease of the amount of developing agents resulted in a more balanced negative, with less development of the highest values without decreasing the overall density of the negatives.

What you've ended up with is essentially a Phenidone subbed, carbonate buffered, divided D-76. That it can deliver pretty good results should not be a huge surprise.

The optimal starting point ratios for PQ/ MQ etc have long been published in the standard reference works (see Levenson in the SPSE manual for example), and it seems that an awful lot of the time all that people are doing is inadvertently demonstrating that Kodak et al did the work correctly the first time round.

Milpool said:
Another problem - "compensation" isn't strictly defined. Based on discussions with some photographers it seems the goal (whether it happens or not is another matter) is basically highlight compression. Two-solution development gives a more linear characteristic curve, though the effect is relatively minor. People likely wouldn't notice a difference if they didn't know they were doing something different.

My own understanding of what people seem to think 'compensation' means is less dense highlights without screwing up midtone gradients via lower average gradient aim. This is essentially what the DIR couplers in XP2 are specificially aimed to deliver, rather than a much longer linear curve at a lower gradient. That people who are messing around with developers often end up doing the latter instead is, I think, the main source of the confusion.

bluechromis said:
It's a little unclear to me what you are referring to with highlight control. Is this like the use of high dilutions and long development times that cause local developer exhaustion in highlight areas?

Yes and no. Development inhibition effects potentially allow for better highlight control, finer granularity and better sharpness. Developer formulation is part of the story, but emulsion structure is arguably even more important. It is a pretty complex and (still) rather commercially sensitive area.

Solvency can allow access to (e.g.) iodide placed in the emulsion such that it will produce inhibition effects where it is released; highly dilute metol only (less than 0.5g/l working solution) can produce desirable effects via exhaustion, but not when a source of semiquinone is added; Phenidone and PQ (etc) developers can deliver inhibition effects without needing very dilute single-shot solutions, and the effects can be altered via the P:Q ratio. Adding 1-Phenyl-5-Mercaptotetrazole (PMT) restrainer can produce useful effects allowing a non solvent PQ developer to still produce fine but sharp granularity (and excellent highlight density control, with the added benefit of massive safety margins for those whose process control is poor or more-talked-about-than-enacted). Some of this has been commercialised by Kodak, Ilford etc in the last 30-40 years (and they've outflanked in research many much-talked-up formulae, subjecting them not just to a battery of properly tough tests of sharpness, granularity etc, but also double blind print comparison tests across wide-ranging enlargement sizes).

relistan · 2025-08-22T05:30:20-0400

Lachlan Young said:
What you've ended up with is essentially a Phenidone subbed, carbonate buffered, divided D-76. That it can deliver pretty good results should not be a huge surprise.

I think you'll find that it's not that at all if you test it. The ratio of the agents is different, the amount of sulfite is different, and the buffer setup is different. So, no, not just divided D-76. Having used quite a lot of divided D-76 (both Haist and Vestal varieties), I can also attest that it works quite differently. Being speed-neutral or speed-boosting (2B-1) vs speed-losing (divided D-76) not being the only major difference. Paul changed the amount and ratio of the developing agents which moves it closer to the ratio that a theoretical D-76 would have if we were to accept that some amount of phenidone substituted for some amount of metol would produce identical results if the superadditive relationship remained the same. That does not make it divided D-76.

relistan · 2025-08-22T05:35:00-0400

Sidd said:
Karl, can you please tell me what is the longevity of a partially used 2B-1 solutions set? And, how many rolls can be processed in a preparation of 1 litre (×2)?

I used a batch for 6 months and maybe 10-12 rolls when kept in airtight containers and with butane on top. It was not dead, but I don't take risks with my film when I can help it. YMMV depending on impurities, etc.

dcy said:
@relistan: I read your blog post about 2B-1 with great interest. Could you tell me a little bit about what you like about 2B-1 compared to Barry Thornton's Two Bath? What does it do differently?

Better speed (no loss, boost on some films), a bit higher contrast though not crazy. @retina_restoration found that the highlights were a litle too much for his work, but for mine I found it nice.

dcy said:
Oh! PC-512 looks interesting. I'm going to read that thread. I'm sure I'll have a question about it soon.

Have a go at it, let me know. A fair few people have used it now and contributed times to the knowledge base on this site.

relistan · 2025-08-22T05:39:38-0400

Here are some 2B-1 examples for those interested:

This is mine, Fomapan 400, 35mm

This is by Paul (@retina_restoration) on Tri-X 120

Why not 2 baths developer only?

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