# Thread: Developer capacity, D-23, and dilution

1. ## Developer capacity, D-23, and dilution

Among the accusations ever leveled at me, exhibiting a command of math and chemistry are not to be found. I'm running a series of tests with D-23, from N+2 to extra-compensating, in both tray and rotary tank (Jobo on a Uniroller). I'd like to be sure I'm not introducing an unrealized variable in my dilutions. My weekly available time for photography, at present, is constrained.
D-23
D-23 capacity, straight, is listed at the equivalent of 16 4x5s per liter (4 8x10s, 320 sq. in.). My question is the minimum amount of this stock solution required when it's diluted; I've been unable to find a clear answer. Specifically, I would think that a liter a working solution of 1:1 would then process 8 (one-shot), one of 1:2 would process 4 and one of 1:3 would process 2. Therefore, my logic runs, a could process only 1 sheet in a half-liter of 1:3; that would be 4 ounces of stock in that working solution to process a single 4x5 sheet. Is that right?
What I have seen often in posts on various sites, is suggestions like, "Well, I would double the total working solution at that dilution, to avoid early exhaustion..."
Since my calculation methods are not infrequently flawed, I will grateful for any scientific correction.

2. ## Re: Developer capacity, D-23, and dilution

The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.

3. ## Re: Developer capacity, D-23, and dilution

Originally Posted by Jim Noel
The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.
Concisely, eloquently correct. No further elaboration required or equivocation appropriate. Great work, Jim!

4. ## Re: Developer capacity, D-23, and dilution

You've got the general idea right -- as you dilute the developer you need to increase the time. A good starting point, is DOUBLE the dilution, DOUBLE the time. But that only goes so far, as mentioned. Developers wear out -- AKA exhaust. This happens sooner as the developer is diluted -- AND it will impact the highlights and shadows deferentially, so the contrast will change. But whatever dilution you use, for however long, you need to run tests to examine the film speed and the contrast.

5. ## Re: Developer capacity, D-23, and dilution

Right, but I develop 4 sheets with about 250ml all the time. When I was shooting Shanghai, I used to develop four sheets with 80ml, but that was definitely not enough for FP4. So, my guess is that different films will require different amounts of developer, but that is just a guess...

6. ## Re: Developer capacity, D-23, and dilution

D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...

Steve K

7. ## Re: Developer capacity, D-23, and dilution

Originally Posted by LabRat
D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...
That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

8. ## Re: Developer capacity, D-23, and dilution

Let me add about D-23 dilution... The excess of sodium sulfite is slightly alkali enough to accelerate metol into development, but it needs a lot present to do it... By even a 1:1 dilution, it cuts that by half, so not enough to activate development much...

Other developers usually contain an additional alkali to maintain the pH level even at higher dilutions, so it can be diluted...

Been a long time since using D-23, but as I (barely) remember, the capacities you listed were about right, as you can use it several times, but a slight decrease in Dmax creeps in...

I remember D-23 as having a nice tonal graduation, but gets a little mushy the bigger the enlargement... (I now prefer a dilute low sulfite one-shot developer that allows better edge effects, and is slightly compensating by developing highlights to exhaustion, but with very good shadow detail, and non-dense highlights that one can easily print additional steps into...)

Steve K

9. ## Re: Developer capacity, D-23, and dilution

Originally Posted by LabRat

I remember D-23 as having a nice tonal graduation, but gets a little mushy the bigger the enlargement... (I now prefer a dilute low sulfite one-shot developer that allows better edge effects, and is slightly compensating by developing highlights to exhaustion, but with very good shadow detail, and non-dense highlights that one can easily print additional steps into...)

Steve K
My experience also. What is the developer you use but don't name?

10. ## Re: Developer capacity, D-23, and dilution

Originally Posted by mdarnton
My experience also. What is the developer you use but don't name?
Hi Michael,

I had used D-23 and D-25 many years ago, but wanted something sharper cutting... (But D-23 was good for taking the edge off T grained films that I don't use...) D-76 tended to be a bit contrasty and hard out here in the Cali sun (but good for flat overcast & foggy conditions), so I hit the books for a formula that had about equal amounts of metol & hydroquinone, and after much searching, I found in the BJP a diluted Crowley variation of the old DK-50 formula, where a standard stock solution of DK-50 is mixed (A), and another B solution of 80 grams of Kodalk per liter into water, where to make a working solution you take 2 parts of DK-50 stock (A), 1 part of Kodalk (B), and seven parts water... (So a liter of working solution is 200ml A, 100ml B, and 700ml water) Development times are just like D-76, but holds highlights much better, fine sharp grain, cleaner working, a restrainer that controls fog, and with slight overexposure/underdevelopment, the grain pattern just follows shadow lines but does not cover image at normal EI... Use one shot... Easy to mix, and stock lasts for a good time... Maybe not for denser alt process negs, but the good but non-dense Dmax is perfect for enlarging + scanning, and great for all formats...

FYI, I'm going to be off-line for awhile (for a walkabout, shooting, and finding a new studio, home, life, etc) I'll check in, but I hope no one burns down the house while I'm gone, so in the meantime, get out there and darken some silver!!!

All good things to y'all!!!

Steve K