Agfa-Ansco-47, pH and developing time

I like very much the Agfa-Ansco-47 formula for its superb mid-tone gradation and very good sharpness.

Metol 1.5g
Sodium Sulfite 45g
Sodium Metabisulfite 1g
Hydroquinone 3g
Sodium Carbonate 5g
Potassium Bromide 0.8g
Water 1l
pH=9.6

However, it's a very fast working formula, with developing times from 4.30mn. (for films ca. EI 100) to 5.30mn (for films ca. EI 400). Since it's sometimes difficult to manage short times with precise temperature and even development, I wonder how to slow down the process.

I tried to dilute at 1+2, but the benefit was'nt so great: the grain became really coarser and the grey-scale much less interesting (at least to my taste).

I wonder if decreasing the pH with a slight addition of boric acid (something like 4 gr.) would keep the excellent image properties of this formula. Does anyone have any suggestion ?

One thing you could try is leave out the Bromide and reduce pH just enough to get rid of fog again. You can test fogging with tiny unexposed test clips, so you won't lose much during testing. Since Boric Acid dissolves very slowly in my experience, you could try Acetic Acid instead, which also leaves buffering mostly unchanged.

The information I have on Agfa 47 advises using 18°C (65°F) and 6-8 minutes as a starting point for developing times. A lower temperature will certainly give you a bit longer developing times. The same info also advocates diluting 1+1 for more manageable times with roll films. That would be something I'd try first. 1+2 might be just a bit too much dilution.

Best,

Doremus

Doremus Scudder said:

The same info also advocates diluting 1+1 for more manageable times with roll films. That would be something I'd try first. 1+2 might be just a bit too much dilution.

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The generally accepted limit for solvent action of Sulfite is considered 30 grams per liter. With the recipe given even 1+1 might be too much. If 1+0.5 and lower temperature won't bring dev times into a region the thread starter likes, other means will be necessary.

One method for extending dev time might be addition of up to 100 g/l Sodium Sulfate (not Sulfite!! ), Na2SO4. This is the recommended technique for slowing down developers to be used in tropical areas with high ambient temperatures.

For me, it is easier to maintain precise temps only when development is short esp., in very cold bath room. For example, 3 mins in each Bath in Divided D-23.

Michael R 1974 said:

Altering the pH of the formula could change other things about its working characteristics

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Sometime it's true, sometimes, not. That's why I asked for opinions, maybee experiments.