Monobath Developers

David A. Goldfarb · Feb 26, 2008

Here's a quick neg scan of the second test exposure--PL100 at EI 100 in FX6a with 90g/l hypo (i.e., the formula as given), 6 min. at 75 deg (which is higher than normal, so that is part of the cause of the excess contrast). The long exposure is probably also partially responsible for the contrast, but on the other hand the light was on the flat side. Tomorrow we should have better weather, so I'll try a test outdoors in normal daylight. There's a little streakiness from the scanner.

Photo Engineer · Feb 26, 2008

David Grenet said:
This is a bit OT I know, but is this why high sulfite developers don't work for the RA4 reversal process? As they use a chloride emulsion?

Yes, this is correct, but there is also another reason.

Sulfite reduces color coupling so if you carry any sulfite excess into the color developer, you can get low dmax. You have to use a very good wash to remove the excess sulfite.

PE

David A. Goldfarb · Feb 26, 2008

So does anyone know anything about the keeping qualities, capacity, and replenishability of monobaths? It would be handy, if I could use this as a deep tank developer. Haist talks about sludging as a factor that would work against this.

David A. Goldfarb · Feb 27, 2008

Getting closer. Here's one with another 10 g/l of hypo (total 100 g/l). What I've learned is that in the FX6a formula, the quantity of hypo controls the development time, which in retrospect is obvious, but doing it makes it all much more intuitive. The neg is still contrasty, but the shadow detail is good, and the acutance is incredible. I think another 10 g/l of hypo, and I'll be there.

Don't mind the out of focus foreground. I was shooting my Tech V handheld using the rangefinder instead of the groundglass and didn't notice that I had forgotten to zero the front tilt from the last shot. The streak along the top is a scanner artifact.

Ian Grant · Feb 28, 2008

FX6a is definitely a very good staring point, back in the early 60's when Crawley published FX6 (Jan 1961) he mentioned that the Hydroquinone could be increased to increase contrast, it can also be decreased slightly. Crawley gives the capacity etc.

Ian

David A. Goldfarb · Feb 28, 2008

Thanks. I figured it would be convenient to be able to keep a batch mixed and adjust the hypo before development, but if that doesn't produce the desired result, I'll mix up a new batch with less hydroquinone.

Ian Grant · Feb 28, 2008

David, just came across this in my notes, I was looking for something completely different:

King's All-in-One

Metol 1.0g
Sodium Sulphite 40.0g
Hydroquinone 5.0g
Sodium Carbonate 30.0g
Potassium Bromide 2.0g
Potassium Iodide 2.0g
Sodium Thiosulphate 13.0g
Water to 1 litre

Monobath.pH should be 8.5; ratio of KI to hypo is critical;
From a 1946 1946 (U.S.P. 2,397,006)

Never tried it, times should be similar to FX-6a

Ian

David A. Goldfarb · Feb 28, 2008

Thanks. I'll have to order some KI and try it some point (probably not for a few months, because we're moving again soon, and I'm trying not to accumulate too much stuff in the darkroom). It looks less expensive than FX-6a, if the capacity is comparable.

David A. Goldfarb · Feb 28, 2008

Today's discovery--too much hypo in FX-6a not only reduces contrast but also increases base fog. I think I'm settling on 105g/l for Efke/Adox 100.

Ian Grant · Feb 28, 2008

David, this was the problem I had when designing a monobath for B&W prints, I'll try and find my notes, they may be around somewhere when I clear out my house next month. From memory I think we added a small amount of Potassium Bromide to cure the problem. The fog is dichroic fog.

Ian

David A. Goldfarb · Feb 28, 2008

Well, one nice thing about monobaths is that they are quick and easy to test.

I tried adding 1 g/l KBr with the 105 g/l hypo that I'd settled on and got less fog, but also less shadow detail, so I tried 1 g/l KBr with 100 g/l hypo and got still less fog, but not as little as I got without the KBr (which suggests something else is going on), but also less contrast than I got without the KBr and the shadow detail looks okay. I'm thinking some of the fog may be partially a film issue, since I'm now using a different emulsion batch (just one month older) than I was using for my first three tests. At this point, I think I'm tweaking at the margins, since the tests are all pretty close to each other.

When the film's all dry I'll post some scans.

Photo Engineer · Feb 28, 2008

David;

Although Grant is the expert on Monobaths, IMHO, I think his belief was that they should be designed or tailored to work with a particular film as they did with the space sattelite films of the 60s and 70s. This was the BiMat film that came in 2 parts, one being the tailored film and the other was the sheet with a sponge like layer of monobath for processing in space and relay of pictures to earth.

In any event, due to all of these problems he had pretty much abandoned the monobath as a viable process for all films for the reason given above and had gone on to designing a product/monobath combination.

His final result was an ID paper that was exposed and then processed by heat giving a fine image with good stability. This can be tracked in patents and reports by Grant and Bill Humphlett and myself. That is pretty much where real 'monobaths' ended up. It contained a developer and a blocked fixing agent / alkali that gave a complete, stable image in about 2 seconds.

I never heard any further efforts on monobaths from Grant after BiMat.

PE

David A. Goldfarb · Feb 28, 2008

Yes, in the book he states that monobaths had to be tweaked to individual films or papers, and that he felt they could produce results as good as conventional developers when used that way, but that that requirement of one formula for one film didn't make them commercially viable.

This makes sense to me, since we wouldn't imagine a conventional developer that would have the same developing time for all films, so in a monobath the developer and the fixer would likewise have to be balanced for each film individually, with a little extra tweaking for problems like fog and sludge (sounds like winter in Rochester).

Ian Grant · Feb 28, 2008

Ron, Crawley wrote a review on Monobaths in the 70's, he'd also done quite a bit of work on them about ten years before, and made references to Haist, unfortunately due to typos his name was misspelt at the time.

My own practical research into monobaths somewhere around 1978/9 indicated exactly what you say "they should be designed or tailored to work with a particular film". When the balance is right the results are very good, if not excellent. It was a descendant of the "Lumiere" family who suggested I look at Monobaths

Ian

Photo Engineer · Feb 28, 2008

You know, it is funny, but I never read "The Monobath Manual" nor did I have a copy of it. I only got a copy of "Modern Photographic Processing" recently, as I could no longer use the EK library easily. It was a case of having "the man" right here a few blocks away or working with me here in my darkroom or at EK that convinced me to not buy either. I had him to talk things over with as a friend, and also I read the "MPP" drafts over and over while helping him edit it.

He used to come over here and we would work in my darkroom. Would you believe that Grant didn't have a home darkroom except for simple B&W film processing? In any event, I've never read the book, but have the word from him and have seen his R&D efforts. Some were quite amazing.

PE

Ian Grant · Feb 28, 2008

From what I remember reading during my research in the 70's the Russian work with Monobaths was far more advanced, there was a lot more innovative research there, but it still hit the buffers.

Ian

David A. Goldfarb · Feb 28, 2008

Out of curiosity, I did a Google search in Russian for "проявляюще-фиксирующий раствор" ("developing-fixing solution," which seems to be the most common term for "monobath"), and I did turn up a PDF of a general B&W processing manual, but a quick search (hey, Acrobat can search in Russian) reveals only a passim reference to monobath processing in space.

David A. Goldfarb · Feb 28, 2008

Here's the result at 100g/l hypo and 1g/l KBr. It's very close to 105g/l hypo with no KBr. The former has a little better shadow detail, the latter has a little more contrast.

Both are very sharp. High acutance seems to be the photographic attraction of this formula.

The streak in the middle of the full scan is a scanner artifact (I've gotta take apart the Duoscan and clean it one of these days). The detail is at 1000 dpi.

Photo Engineer · Feb 28, 2008

Ochin Chorosho Davidovich.

PE

David A. Goldfarb · Feb 29, 2008

Spasibo bolshoi.

I thought I'd post the shot with 105 g/l hypo and no KBr for comparison. The light is better in this shot, so I thought that accounted for most of the differences, but I was looking at the negs more carefully, and this mornining, I'm thinking this version of the formula is a little better. More testing to do, I guess.

Photo Engineer · Feb 29, 2008

No problems with dichroic fog? That was one of Grant's fears in some baths. And, IIRC (been thinking about this), he used an organic antifoggant in some cases. Benzotriazole?

He also used some mixed fixing agents.

PE

David A. Goldfarb · Feb 29, 2008

I've got some fog both with and without the KBr, but it seems related to switching film batches, so it might not be or might not entirely be dichroic fog. It was a little better with KBr added, but only slightly. I'm going to try some rollfilm from yet another emulsion batch. I ran out of film from the first batch, which didn't have a fog problem. It could also be a film storage issue, since the two boxes of 4x5" had a somewhat different storage history.

Photo Engineer · Feb 29, 2008

Well, Grant did use thiocyanate at very low levels in some experiments and some organic fixing agents that were never used commerically by EK. He also used a few that were used commercially.

PE

David A. Goldfarb · Feb 29, 2008

Yes, several of the formulas in the book use organic compounds that I've never used before, and I think there's a thiocyanate formula or two in there as well, and a section on mercaptoacetic acid formulas.

Another attraction of FX-6a that I noticed yesterday, incidentally, is that it's completely odorless.

Photo Engineer · Feb 29, 2008

David;

It just came to mind that some of Grant's favorite chemicals were the same as those used by Henn in designing Microdol and Microdol-X to prevent dichroic fog. I would have to look them up, but I think they are mentioned here and also in A&T.

Modern films contain ingredients that tend to repress dichroic fog.

PE

Monobath Developers

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