# 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

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.

4. ## 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!

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

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

8. ## 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.

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

Thanks to all.
As I have been simplifying most factors of my work, returning after about 12 years, D-23 seemed a good choice for cost, ease, and versatility with the other characteristics I want for location portraiture in MF and 4x5 with a sinle film HP5+. My tests are running from very compensating to N+2 or so; so far I've had no trouble approximating N-1 to N+2 using 1:1. I'll get to testing straight times, and to more compensating results for very long-range subjects using higher dilutions and moderated agitation, perhaps even 2-bath, if needed. I just want to know what I can do so that I can respond to existing illumination as I choose. Per Ansel, chance favors the prepared mind.
A colleague recently suggested the original Gainer's developer -- also cheap and simple -- which I'll try provisionally; I could use in 4x5 the additional speed he seems to get; not sure I want higher acutance. My results with D-23 so far have not supported EI400; I'm back to 200 or 250, as I was for decades; I thought I might do a little better, but I can live either way. I'll settle on whichever developer provides a negative with the qualities I want. I'll be printing silver; no scanning for me, except from prints to post occasionally on line (here and Flickr).
Again, thanks.