Alkaline vs. Acid fixers

[Photo Engineer]

to stop development I understand, but won't the developer traces on the paper or film start developing again in the alkaline fixer unless you wash them off after the stop bath.

It could, but by that time most of the developer has been washed out into the stop.

PE

 

[ericdan]

At what pH does ascorbic acid or metal developer start working?
Alkaline Fixers are only around 8.0 I think. Is that even alkaline enough for most developers?

 

[ericdan]

Sorry my bad. RauschenOderKorn already answered that.

 

[RauschenOderKorn]

At what pH does ascorbic acid or metal developer start working?
Alkaline Fixers are only around 8.0 I think. Is that even alkaline enough for most developers?

Actually I have not. This question is rather complicated, especially if you look at the big picture with stop bath / alkali fixer and include the white light turned on after the stop.

Most modern developers require an akali to work, and if I remeber correctly, one rule of thumb is: the higher the ph, the faster the developer. Looking around a bit, there seem to be formulas which work at pH 8, for instance the "Swedich Ascorbic Acid Developer" also discussed on this Forum (https://www.photrio.com/forum/threads/swedish-ascorbic-acid-developer.127585/).

Nevertheless, the ph is only one of the variables for the results of the development, other relevant variables with your question are exposure of the film, developer concentration, time, temperature, and probably many more. And then there is the effect of the stop bath, washing away the developer and furthermore it might interfere with the developing chemistry (e.g. the HQ-SQ balance in lith development), among other effects.

The way I work (with no exposure until fixing is almost complete), developer concentration is extremely low (washed away in the stop), ph is near neutral, exposure/temperature is not changing, time until clearing is short (at least in comparison to the dev time), so I would not expect (and have not experienced any) activity which leaves a visible mark.

In the case of your film which got fogged, you turned on the light after the stop bath. Now the film should have lost most of its sensitivity due to "washing" in the developer and the stop, but some sensitivity remains. Furthermore, you have given the film a rather generous portion of light, instead of maybe 1/50 @ f5,6 you gave it let´s say 45 sec @ full open (don´t take this literal, just examples for ilustration). So while your developer in the fix might be very dilute and weak, and remaining sensitivity is low, you have increased exposure by something in the order of around n+20 which apparently was just the right amount of light to counter all the other effects with that particular film/developer combination.