How long can I keep my developer.

[Terry Christian]

Don't forget that Freestyle markets a clone of XTOL, so you don't necessarily have to cease XTOL if you want to jump ship from Kodak but otherwise like it.

[Nikonic]

A replenished developer system recycles most of the developer after use. An amount of either a specific replenisher or fresh developer is added to maintain the developer's strength. An example would be D-76 used with replenisher D-76R. It's economical but there is some change in the developers action after each replenishment cycle. People tend to either love the idea or hate it.

But what is actually happening on a chemical level with these marketed replenishers. Is it an alkali to get the PH back up where it should be? Are there compounds that react with redox byproducts and clear them up or sludge them out? Or is it just a fresh jolt of whatever the reducer was?

[Mr Bill]

But what is actually happening on a chemical level with these marketed replenishers. Is it an alkali to get the PH back up where it should be? Are there compounds that react with redox byproducts and clear them up or sludge them out? Or is it just a fresh jolt of whatever the reducer was?

Essentially the byproducts are diluted out with replenisher. (The excess volume either overflows or is carried over into the following solution.) Compared to the processing tank solution, the replenisher is a bit overconcentrated with both developing agent and preservative. Also the pH is higher to boost the tank pH back up a bit.

In the systems that are replenished with original developer, obviously the initial tank solution must change during processing, and should eventually reach some different equilibrium levels. I'd guess that the B&W systems have a large error tolerance which allows this sort of thing. My experience has mainly been in large scale color neg and paper systems, which are generally too finicky for this sort of thing.

[MartinP]

That sounds like an astonishingly ineffective developing tank. Do you really mean a litre for a couple of rolls of 35mm?! If that wasn't a typo then the first step towards economy would be to replace the tank with a more normal one.

Apart from APX100 and Rodinal (which go so very well together) I seem to use ID11 1+1 for most things, with 1+3 for sheets in trays. This works out at a very reasonable point for cost/longevity when I buy the five litre packs, and is also a very standard and repeatable choice. Occasionally for HP5+ at a higher speed I would use DDX, but there isn't that much difference unless you are going over ISO800.

[Nikonic]

Essentially the byproducts are diluted out with replenisher. (The excess volume either overflows or is carried over into the following solution.) Compared to the processing tank solution, the replenisher is a bit overconcentrated with both developing agent and preservative. Also the pH is higher to boost the tank pH back up a bit.

In the systems that are replenished with original developer, obviously the initial tank solution must change during processing, and should eventually reach some different equilibrium levels. I'd guess that the B&W systems have a large error tolerance which allows this sort of thing. My experience has mainly been in large scale color neg and paper systems, which are generally too finicky for this sort of thing.

I guess if you were running 10,000 negs through a machine a month this would end up being economical. But I don't see why anyone would bother with it on a small scale. Just make a new batch.

[MattKing]

I guess if you were running 10,000 negs through a machine a month this would end up being economical. But I don't see why anyone would bother with it on a small scale. Just make a new batch.

Using a 250ml tank and stock XTol as an example...

5 litres of XTol stock used one-shot: 20 rolls developed
5 litres of XTol stock used in a 70 ml replenishment regime: the first 5 litres will develop 57 rolls, and all subsequent 5 litre packages will develop 71 rolls.

And your working strength developer will always be at room temperature.

[fotch]

I prefer to use developers once and discard, for color or B&W. The solution for me was to get a bunch of 250ml Amber Glass Bottles to be able to mix up Xtol (20 bottles) or D76 (16 bottles) and store (in smaller bottles) with no air so it would last longer. Then I could use one shot or 1:1. Of course, it will work with any developers. I also use a layer of Saran wrap between the cap & bottle for extra sealing, just in case.

If you need some, I have lots of extra bottles.