Does first development in a reversal process go to completion? And what exactly is development to completion?

River Mantis · Nov 9, 2023

I've seen a statement that in a reversal process the first development goes "to completion". And the paper development goes "to completion" too. First of all what does it mean? My naive understanding is that completion is a point in time when all potentially developable grains are developed (not counting the fogging process). If this is true then the final density of the given emulsion developed to completion is defined by exposure only (and the fog level) and the developer contrast characteristic stops playing any role as it affects the dynamics only (the balance between positive and negative feedbacks).
I'm actually trying to understand what characterise a reversal developer. Haist in vol.2 doesn't use the term "completion" in this context. He describes reversal developers once as "vigorous" and once as "vigorous and contrast". Does it mean that developer must be contrast-working to actually bring more contrast to the image or just do drive the process to completion as fast as possible (and let the emulsion show it's natural full contrast)?

Augustus Caesar · Nov 9, 2023

River Mantis said:
I've seen a statement that in a reversal process the first development goes "to completion". And the paper development goes "to completion" too. First of all what does it mean? My naive understanding is that completion is a point in time when all potentially developable grains are developed (not counting the fogging process). If this is true then the final density of the given emulsion developed to completion is defined by exposure only (and the fog level) and the developer contrast characteristic stops playing any role as it affects the dynamics only (the balance between positive and negative feedbacks).
I'm actually trying to understand what characterise a reversal developer. Haist in vol.2 doesn't use the term "completion" in this context. He describes reversal developers once as "vigorous" and once as "vigorous and contrast". Does it mean that developer must be contrast-working to actually bring more contrast to the image or just do drive the process to completion as fast as possible (and let the emulsion show it's natural full contrast)?

No, that's false. First development goes to a specific point, intended to give best results. Color development goes to completion, as do all the other steps in E-6 or other similar processes.

Ivo Stunga · Nov 10, 2023

With reversal one can push, pull or go for box speed - exactly as with normal negatives.

It's the reversal that defines the reversal process, bleach, reexposure and redevelopment doing their things - making this a fine-grain, high-contrast process in most applications I encounter it, that can handle great enlargements.
Up to the bleach and re-exposure you've just developed your film in a strong/paper developer - interesting, but not that much.

Agitate less and use weaker solutions = control the contrast.

mshchem · Nov 10, 2023

1st developer in E6 is very critical, time,temperature, agitation, developer activity.

mshchem · Nov 10, 2023

River Mantis said:
I've seen a statement that in a reversal process the first development goes "to completion". And the paper development goes "to completion" too. First of all what does it mean? My naive understanding is that completion is a point in time when all potentially developable grains are developed (not counting the fogging process). If this is true then the final density of the given emulsion developed to completion is defined by exposure only (and the fog level) and the developer contrast characteristic stops playing any role as it affects the dynamics only (the balance between positive and negative feedbacks).
I'm actually trying to understand what characterise a reversal developer. Haist in vol.2 doesn't use the term "completion" in this context. He describes reversal developers once as "vigorous" and once as "vigorous and contrast". Does it mean that developer must be contrast-working to actually bring more contrast to the image or just do drive the process to completion as fast as possible (and let the emulsion show it's natural full contrast)?

RA4, is the only thing I know that you can blow past 45 seconds (100°F, constant agitation) in the developer and still get an acceptable result. Completely different from film. Even with RA-4 if the activity of the developer isn't controlled (use starter and proper replenishment) and consistent agitation, you will not have success.

Philippe-Georges · Nov 10, 2023

mshchem said:
1st developer in E6 is very critical, time,temperature, agitation, developer activity.

Not to mention the colour developing (the second or redeveloper thus) which defines the colour balance by, amongst others, it's acidity...
But this is of less importance in B&W reversal, which, by the way, is magnificent for the mechanical printing process...

mshchem · Nov 10, 2023

Philippe-Georges said:
Not to mention the colour developing (the second or redeveloper thus) which defines the colour balance by, amongst others, it's acidity...
But this is of less importance in B&W reversal, which, by the way, is magnificent for the mechanical printing process...

Agreed!

Romanko · Nov 10, 2023

River Mantis said:
I've seen a statement that in a reversal process the first development goes "to completion".

"Completion" would mean conversion of ALL silver halides to metallic silver. In a (color) reversal process you need to develop to a specific gamma.

Does first development in a reversal process go to completion? And what exactly is development to completion?

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