Question for chemistry--especially D-23--experts

[Ulophot]

I have recently been running some tests in which I develop a single sheet of film at a time in my SP-445. I generally use D-23 1:1, which, conveniently enough, has a stated capacity of 4 sheets per 16 oz of D-23 1:1 (though it's not exhausted by then; some use it significantly more). As inexpensive as D-23 is, I would still prefer to use those 16 oz. more than once in such tests, if I'm doing them in one session.

The question, therefore, is, by what percentage do I increase the time for the second and third runs? (I don't mind mixing fresh for the fourth.) I used to reuse Microphen (a much more energetic developer, and I was using it stock-strength) for 9-10 rolls, increasing development 10% per roll developed, but that's my only experience with developer reuse.

[xkaes]

I'm not familiar with the SP-445, and it's been a while since I used D-23, but if you are mixing D-23 yourself, it's as close to free as you can get. Since I only use about two ounces of developer per 4x5" surface, I always use fresh stuff -- just to avoid any testing and calculations regarding re-use of chemicals. It's the same with stop and fixer.

But I do always run some basic density tests -- ONCE -- to determine the best time/temperature/dilution for my needs. After that, I don't need to change anything.

[Michael R]

Time compensation for unreplenished re-use depends on the developer and on variables including solution volume, and this assumes stock solution strength (such as your Microphen example). From a capacity perspective, D-23 should be similar to Ilford Perceptol, so I would suggest using Perceptol instructions and extrapolating. However generally you won’t find any directions from manufacturers for re-use of diluted developers as they are virtually always intended for one-shot use. This doesn’t mean you can’t try re-using D-23 1+1. What a mean to say is that you’ll have to figure out time compensation etc. empirically with your own testing. Any information out there on this will be anecdotal at best.

[paulbarden]

D-23 diluted 1:1 shouldn't be reused, period. If you want to use D-23 stock solution, then follow Michael's recommendation.

[Jim Noel]

D-23 is too cheap to use multiple times on expensive film. I can mix many gallons for the cost of one sheet of 5x7 film.

[Wheathins]

I have recently been running some tests in which I develop a single sheet of film at a time in my SP-445. I generally use D-23 1:1, which, conveniently enough, has a stated capacity of 4 sheets per 16 oz of D-23 1:1 (though it's not exhausted by then; some use it significantly more). As inexpensive as D-23 is, I would still prefer to use those 16 oz. more than once in such tests, if I'm doing them in one session.

The question, therefore, is, by what percentage do I increase the time for the second and third runs? (I don't mind mixing fresh for the fourth.) I used to reuse Microphen (a much more energetic developer, and I was using it stock-strength) for 9-10 rolls, increasing development 10% per roll developed, but that's my only experience with developer reuse.

If d23 is similar to perceptol, ilford doesn't recommend reuse of any kind for diluted applications. When I use perceptol I use the most dilute combo and use one shot.

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[Tin Can]

Listen to Jim

D-23 is too cheap to use multiple times on expensive film. I can mix many gallons for the cost of one sheet of 5x7 film.

[Ulophot]

Soooo, calling me a cheapskate, eh? Okay, okay, fair enough. Down the drain it goes.

[Bill Burk]

If you have a sensitometer and densitometer, you can figure it out. Practically everyone has said it's not worth it and I agree.

But I have done a similar test and know how to do what you are trying to figure out.

Here are the steps: Include a sensitometric strip in each run of your processing. Read the results and graph them and determine the contrast from each test. Compare the results with a time/contrast graph (that you created by normally processing tests for several different development times).

I once performed the tests with D-76 1:1 re-used 3 times but developed for the same time.

My personal answer to the question "What happens if I re-use D-76 1:1 past capacity' but keep the times the same?": I lose 'thirty percent' contrast with each run.

[Bill Burk]

Soooo, calling me a cheapskate, eh? Okay, okay, fair enough. Down the drain it goes.

One day you will be facing a deadline (like a friend's birthday and you want to give them a portrait), on your last batch of chemicals, and all the camera stores are closed...