Physical Development

[sergio caetano]

Definition: Some of the silver dissolved by the solvent is replated back onto developing sites on the film.
I have read (do not remember where, perhaps in Popular Photography some decades ago) that some of these silver particles do not go back to their original locus, and are deposited on other places including some unexposed areas.
Harmful phenomenon of developers with high content of sulfite.
Comments about that ?

 

[Milpool]

It was more of a potential issue in the old days - old emulsions and/or certain types of extra-fine grain developers, and in high volume re-use/replenishment applications.

 

[sergio caetano]

Milpool
"old emulsions and/or certain types of extra fine grain developers"
What about today with D76 and D23 (undiluted) ?

 

[John Wiegerink]

Milpool
"old emulsions and/or certain types of extra fine grain developers"
What about today with D76 and D23 (undiluted) ?

Shouldn't be a problem with almost any film emulsion made today.

 

[Milpool]

Milpool
"old emulsions and/or certain types of extra fine grain developers"
What about today with D76 and D23 (undiluted) ?

Shouldn't be an issue with modern films and even historically while D-76 and D-23 are solvent developers they are not the problematic type. Standard solvent developers like this would only potentially cause silver replating/fog or sludging issues in certain high volume / heavy re-use applications.

 

[Alan Townsend]

Definition: Some of the silver dissolved by the solvent is replated back onto developing sites on the film.
I have read (do not remember where, perhaps in Popular Photography some decades ago) that some of these silver particles do not go back to their original locus, and are deposited on other places including some unexposed areas.
Harmful phenomenon of developers with high content of sulfite.
Comments about that ?

I believe this is common with most "fine grain" developers today including Xtol, MicrodolX, d76 and d23 using stock solution. Also common in antiquity, the Daguerreotype where boiling mercury is used to develop silver halides on a silver coated plate of metal, or during wet collodian era where ferric chloride was used as physical developer due to large amounts of silver nitrate present in films. Today good for fine grain, bad for acutance. One to three diluted xtol, d76 or d23 become nonsolvent developers and give better acutance, especially d23. The acutance/fine grain preferences have been argued a lot over the years by various people, but I believe Americans tend to prefer fine grain while Europeans and especially English Europeans lean the other way to a large degree.

The grain in developed film is not noise, it is the result of the light sensors being grains of silver halide chemicals in the film that have moved around a bit during development. Grains are the shapes of the light sensors, which are random sizes and shapes and depths in the emulsions, unlike the perfect square matrices of sensors on electronic sensors which are perfect and fixed.