Underdeveloped negs in homemade Diafine

Hi everyone,

I made a batch of Diafine at home following Anchell's formula in his book The Darkroom Cookbook 3rd edition.

Measured the chemicals out carefully and my raw chemicals were fresh (opened first time on the day). Used a magnetic stirrer and heater to make sure it all dissolved.

I just developed a bunch of HP5@800 in it for 3.5+3.5 minutes and they came out really underdeveloped. I wonder why?

I have not reviewed the DIY formula offered as "Diafine" nor used it. In the 1960s when Diafine was introduced I used it once along with its cousin, Acufine, and decided both were too course grained for my liking. I'll offer you two possible reasons for your thin negatives. Diafine, being a split developer, works by absorbing developing agent from the first bath into the emulsion. The film is then transferred to the second bath (without wash) where development is activated by an alkaline solution. Development proceeds until all of the absorbed developing agent has been consumed, then it stops. Once minimum times in each bath are reached, additional time in either bath has no effect, as the emulsion can absorb only so much developing agent, and once it's used up, your done. So, first reason: modern film emulsions are physically thinner than they were 50 years ago. Modern HP-5 may not absorb as much developing agent as a similar film in 1965. Second, understanding how Diafine works shows that it's not a developer in which film speed can be "pushed". It gives you one development event, which may or may not be the same as Normal for another developer, but it's the only one you get. It is fairly insensitive to changes in development time or temperature. When you exposed your HP-5 at 800, you under-exposed one stop, thus thin negatives. Originally. Diafine advertised that it naturally delivered an effective film speed which was 1/2 to 1 stop faster than box speed, but that was in a day and in a marketing environment where "faster is better" and should be written off as market puffing unless your personal tests show otherwise.

When I was a working PJ in the 70s and 80s I usually had a quart kit of Diafine to use in the field. In the Congo I used washed out beer bottles, no stop bath, quart can of fix, and small bottle of photoflow, bottled water. It was easier to get negatives past customs than prints or a can of film. In those days I could push Trix to 1600, with the modern version maybe 800, still HP5 at 800 should be within reach, either you meter is off, or something wrong with the formula. And BTW, no stop, did you use a stop?

Last time I used real Diafine, I found Tri-X (in 2003, and it might have been 1990s Tri-X, I don't recall) came out at EI 640 -- that's 2/3 stop increase. Tri-X has been reformulated at least twice since then, IIRC, and the Anchell "Diafine" was never confirmed to match actual Diafine.

The things we know for certain: Diafine used phenidone and hydroquinone, which combination will usually yield a modest speed increase when developed to normal contrast. As noted above, film has changed a lot since Diafine was introduced, and modern film carries less developing agent into the accelerator bath, so you may be getting less development, giving lower contrast, and offsetting the expected speed increase.

If it's two-bath convenience you're after (little temperature control needed, timing very much non-critical, doesn't even need agitation other than on filling, to be sure you get the air out), shoot a bracketed test roll to find your correct EI and enjoy the easy way of development. if you're after a speed increase, I'd suggest selecting any phenidone- or dimezone-based conventional developer (Ilford PQ Universal, Xtol, E-76, etc.), diluting as far as manufacturer's data will support, and developing as if for a 2 stop push, but agitating only 10 seconds every third minute after the continuous first minute. This will get all the true speed you'll ever see with normal contrast (you may need to adjust your time a little, depending what you consider normal contrast).

And if you're just experimenting to see what you like, carry on.

The 'recipe' is likely wrong - the cookbooks have a number of errors of transcription & a worrying lack of useful testing by the authors. And I'm not really surprised by Donald's results - I'd almost be more shocked if a reasonably well designed PQ film developer didn't deliver up to 2/3 stop shadow speed gain over ISO. Add the 1-stop underexposure latitude (not a big deal in challenging lighting environments with poor shadows anyway) and you're at a claimable EI of 1250.

Like the OP, I could never get good negs out of that formula. I've been working on substituting sodium carbonate instead of borax with improved, but not great results. Diafine warns against using a stop bath and I think this was because of a healthy dose of carbonate in the formula, not borax. So far, my experiments have not yielded anything superior to the real stuff.

Randy Stewart said:

It gives you one development event

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With Diafine there is a "not regular" way to have more than one "development event". After second bath we can wash film with tap water, then immersing it again in the first bath (than it can be more diluted this time), an later we perform again the alkaline second bath to continue development with an additional dose of developer.

A similar workflow can be used to decrease the compesating effect of diafine, not allowing all second bath time, washing, recharging developer agent in the first bath and immersing again in the alkaline bath.

Also the compensating effect of diafine can be emulated with intermitent water bath, this is using a regular single bath developer but immersing the film intermitently in plain water to promote increasing developer exhaustion in the increasing highlights.

Lachlan Young said:

the cookbooks have a number of errors of transcription & a worrying lack of useful testing by the authors.

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Not much errors in Anchell's cookbooks.

Here you have the errata sheet of the previous film developing cookbook: https://anchellworkshops.com/books/errata/fdc_errata.pdf

Also if you serch the darkroom cookbook 1st edition errata you'll find not much real problems. Anyway lab rats always check errata sheets.


Most of problems come when the cookbooks speak about religion, like water stop bath, presoaking, fixers, washing and rotary drawbacks