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- Apr 7, 2018
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- 52
Thank you Ian i will try it.
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First decent paper negative
- Thread starter joe monteiro
- Start date
Ian,
Could you clarify the difference between development to completion and development to exhaustion? I'd always believed that very long development times with very dilute developer depended on the active component of the developer being entirely, or practically entirely, consumed.
Conversely, I've been assuming that development to completion involved using up all the activated crystals in the emulsion. From my experience, prolonging print development produces only a relatively small increase in image density, before general fogging sets in, which is why we must remove the print from the developer after the proper time. Fogging seems to be a different matter and can happen to unexposed paper too.
With film, we commonly curtail development to control contrast but there must be a point that's analogous to print development, where only useless fog is produced by extra time.
Neither is an exact description. This is my own fumbling in the dark.
Could you clarify the difference between development to completion and development to exhaustion? I'd always believed that very long development times with very dilute developer depended on the active component of the developer being entirely, or practically entirely, consumed.
Conversely, I've been assuming that development to completion involved using up all the activated crystals in the emulsion. From my experience, prolonging print development produces only a relatively small increase in image density, before general fogging sets in, which is why we must remove the print from the developer after the proper time. Fogging seems to be a different matter and can happen to unexposed paper too.
With film, we commonly curtail development to control contrast but there must be a point that's analogous to print development, where only useless fog is produced by extra time.
Neither is an exact description. This is my own fumbling in the dark.
- Joined
- Dec 19, 2017
- Messages
- 2,712
David, you are right the correct meaning of Development to completion means total development of all the available silver halide.
The only times we develop to completion are in reversal processing in the second developer, with Black and White reversal processing or E6. That wasn't always the case earlier earlier reversal processes used second development to a set Dmax by time and temperature.
The term Development to Completion is used incorrectly to mean a little longer than achieving the Dmax of a paper, but the term is meaningless with Warmtone papers where we deliberately under develop to achieve greater warmth compensating by increased exposure.
I've not seen the term Development to Exhaustion used specifically but developer exhaustion is used as a method of compensation development where there's a highly dilute developer and insufficient volume so the developing agents exhaust. It's not necessarily coupled to long development times, it'll happen with ID-11,/D76, Xtol, etc, at 1+3 unless you use a larger than normal volume of developer.
Ilford did research in the 1950's into the actual amounts of developing agents used to develop each film (or rather a set area), this was part of their work to formulate Autophen their commercial PQ photofinishing variant of ID-11/D76. This allowed accurate top up replenishment which is very economic, ID-11/D76 needs bleed replenishment where a more significant volume is drawn off and discarded before replenisher is added to keep the Bromide build up under control, Metol's activity is suppressed by Bromide build up whereas Phenidone is relatively unaffected, so replenishing ID-11/D76 is quite inefficient and costly.
Of course the same has since been done for machine processed colour films and colour or B&W papers.
What Ilford's conclusions meant was it's possible to look at the actual amount of developing agent needed to process a film (usually approx 80 square inches) and also the amount of developing agent available in the chosen volume of working strength developer. You need excess developing agents for efficient development.
Ian
The only times we develop to completion are in reversal processing in the second developer, with Black and White reversal processing or E6. That wasn't always the case earlier earlier reversal processes used second development to a set Dmax by time and temperature.
The term Development to Completion is used incorrectly to mean a little longer than achieving the Dmax of a paper, but the term is meaningless with Warmtone papers where we deliberately under develop to achieve greater warmth compensating by increased exposure.
I've not seen the term Development to Exhaustion used specifically but developer exhaustion is used as a method of compensation development where there's a highly dilute developer and insufficient volume so the developing agents exhaust. It's not necessarily coupled to long development times, it'll happen with ID-11,/D76, Xtol, etc, at 1+3 unless you use a larger than normal volume of developer.
Ilford did research in the 1950's into the actual amounts of developing agents used to develop each film (or rather a set area), this was part of their work to formulate Autophen their commercial PQ photofinishing variant of ID-11/D76. This allowed accurate top up replenishment which is very economic, ID-11/D76 needs bleed replenishment where a more significant volume is drawn off and discarded before replenisher is added to keep the Bromide build up under control, Metol's activity is suppressed by Bromide build up whereas Phenidone is relatively unaffected, so replenishing ID-11/D76 is quite inefficient and costly.
Of course the same has since been done for machine processed colour films and colour or B&W papers.
What Ilford's conclusions meant was it's possible to look at the actual amount of developing agent needed to process a film (usually approx 80 square inches) and also the amount of developing agent available in the chosen volume of working strength developer. You need excess developing agents for efficient development.
Ian
- Joined
- Aug 6, 2016
- Messages
- 1,586
When I use RC Paper, I find that ISO 3 is a good starting point for a dullish day. Adding a yellow filter seems to help as well in taming the highlights.