Chemistry: On Futher Dilution Of D-23 And Lye

chuckroast · Thursday at 10:53 PM

I have been using D-23 1+9 with 0.5g/l lye added to restore the required alkalinity to good effect.

If I wanted to further dilute - in hopes of establishing even greater acutance - is there a fairly straightforward way to calculate the required increase in NaOH, short of measuring with a pH meter and adding lye until it hit the magic number?

In a related question - as a general matter, I have read that increasing alkalinity - up to a point - will also increase edge effects. Is there some calculated way to approach this or is all just experimental fiddling?

Finally, I use lye in minuscule amounts but the container is sold in 1kg quantities. When I last went to use some, the top of the lye hardened into a kind of 5mm cake and I had to break through it to get to the normal lye below. Is lye hygroscopic, and can that "cake" be used or should it be discarded each time?

TIA,
CR

F4U · Thursday at 11:00 PM

I don't know about that. But if you are using D-23 1:9, I can't imagine what you are doing about the developer capacity situation. You must be mixing up a gallon to develop a single 35mm roll

Milpool · Thursday at 11:11 PM

The short answer regarding your developer is you will need to do this empirically.

There is no magic pH you are looking for. Even the relatively small amount of sodium hydroxide is giving you a pretty high pH when added to D-23 which has been diluted to 1+9, so the initial pH will be at least that high if you dilute the developer further.

If you are interested in edge effects you might find this RIT paper interesting.

https://repository.rit.edu/cgi/viewcontent.cgi?article=7664&context=theses

The author explores metol and Phenidone, the effects of concentration of the developing agent, pH, sulfite levels and superadditivity.

Dilute metol a-la Beutler (and beyond) works well but you also might want to try POTA as an alternate starting point for maximum edge effects.

There are several contributing elements to sharpness and how you define it makes a difference.

As you go, make sure to evaluate tone reproduction as the concoctions become more extreme.

Sodium hydroxide is hygroscopic.

chuckroast · Thursday at 11:14 PM

F4U said:
I don't know about that. But if you are using D-23 1:9, I can't imagine what you are doing about the developer capacity situation. You must be mixing up a gallon to develop a single 35mm roll

I am using 2l at a time to process sheet film or roll film. It works splendidly, at least with extended development.

mshchem · Thursday at 11:22 PM

Sodium hydroxide is very hygroscopic. It will form a very nasty puddle if left in the open. Might want to make a 10g/ 500mL stock solution and store in a heavy duty HDPE plastic bottle.

Maybe get some pH strips. I wouldn't think you would need much additional lye as it's such a strong base.

Raghu Kuvempunagar · Friday at 12:25 AM

chuckroast said:
I have been using D-23 1+9 with 0.5g/l lye added to restore the required alkalinity to good effect.

If I wanted to further dilute - in hopes of establishing even greater acutance - is there a fairly straightforward way to calculate the required increase in NaOH, short of measuring with a pH meter and adding lye until it hit the magic number?

As we know D-23 1+14 with 2.5 g/l Sodium Carbonate is nearly the same as Crawley's FX-1 (without the homeopathic addition of Iodide). So you may want to give D-23 1+14 with 0.5g/l Lye a chance and increase Lye in small amounts (0.1g) at a time if there is underdevelopment.

Alan Johnson · Friday at 5:24 AM

It is possible to get a measure of the adjacency effect with various films by photographing a light grey card on top of a dark grey card, semi-stand developing in the type of developer you mention and making a 10x enlargement of the light/dark edge. A light line is visible at the edge. It works best with the old low iodide films like Efke.

Donald Qualls · Friday at 9:27 AM

Instead of further dilution, I'd suggest you first try reducing your agitation. Assuming you're agitating every minute, try agitating only every third minute (keep the same time for a first test, but be prepared to extend your development further, as lower agitation will often slow the overall process). A side effect of this reduced agitation is that shadows will develop more than highlights (due to local exhaustion) giving a compensating effect (nice for preserving details in clouds when exposing for the land on a landscape, for instance).

You could even stretch to agitating every five minutes, but that's unlikely to gain anything noticeable over three minutes.

chuckroast · Friday at 9:50 AM

Donald Qualls said:
Instead of further dilution, I'd suggest you first try reducing your agitation. Assuming you're agitating every minute, try agitating only every third minute (keep the same time for a first test, but be prepared to extend your development further, as lower agitation will often slow the overall process). A side effect of this reduced agitation is that shadows will develop more than highlights (due to local exhaustion) giving a compensating effect (nice for preserving details in clouds when exposing for the land on a landscape, for instance).

You could even stretch to agitating every five minutes, but that's unlikely to gain anything noticeable over three minutes.

I've used semistand and EMA for years, so I don't think I could agitate any less

chuckroast · Friday at 9:52 AM

Raghu Kuvempunagar said:
As we know D-23 1+14 with 2.5 g/l Sodium Carbonate is nearly the same as Crawley's FX-1 (without the homeopathic addition of Iodide). So you may want to give D-23 1+14 with 0.5g/l Lye a chance and increase Lye in small amounts (0.1g) at a time if there is underdevelopment.

Yes, I came to much the same conclusion. I think this is easier than getting out the pH meter and trying to match exactly the current concoction...

Saganich · Friday at 10:34 AM

I was curious about this question...I found this somewhere...but can't validate it's accuracy. I believe the sweet spot for edge effect for D23 is 9.5ish with development to exhaustion. Phenodine, I have read, can enhance the edge effects when added in very small amounts to Metol. I have seen this in the form of Mackie lines when using FX2 agitating 10 seconds per 2 minutes for 20 min dev time.

If you add 1 mg NaOH to 1.0 L of water you will increase the pH

What will the pH be ?
Molar mass NaOH = 40 g/mol
Mol NaOH = 0.001 g / 40 g/mol = 0.000025M
[OH-] = 0.000025 M
pOH = - log 0.000025
pOH = 4.60
pH = 14.00 - 4.62
pH = 9.38

Calculation refers to absolutely pure H2O totally free of any dissolved substances including CO2

chuckroast · Friday at 10:49 AM

Saganich said:
I was curious about this question...I found this somewhere...but can't validate it's accuracy. I believe the sweet spot for edge effect for D23 is 9.5ish with development to exhaustion. Phenodine, I have read, can enhance the edge effects when added in very small amounts to Metol. I have seen this in the form of Mackie lines when using FX2 agitating 10 seconds per 2 minutes for 20 min dev time.

If you add 1 mg NaOH to 1.0 L of water you will increase the pH

What will the pH be ?
Molar mass NaOH = 40 g/mol
Mol NaOH = 0.001 g / 40 g/mol = 0.000025M
[OH-] = 0.000025 M
pOH = - log 0.000025
pOH = 4.60
pH = 14.00 - 4.62
pH = 9.38

Calculation refers to absolutely pure H2O totally free of any dissolved substances including CO2

That's pretty clear (and thanks!). Do you have the source?

Saganich · Friday at 11:00 AM

I found it...https://www.quora.com/How-much-NaOH-is-needed-to-increase-the-pH-of-water.. ALSO CORRECTION...Not Phenodine but Glycine and Metol... I got that confused.

chuckroast · Friday at 11:34 AM

Saganich said:
I found it...https://www.quora.com/How-much-NaOH-is-needed-to-increase-the-pH-of-water.. ALSO CORRECTION...Not Phenodine but Glycine and Metol... I got that confused.

The calculation is easy enough to follow but I still have questions I need to explore:

If the calculation above is correct, then my use of 0.5g/l of NaOH seems like real overkill
I would love to see the derivation of this calculation rather than just the mechanical maths

Not asking you for that, just ruminating on what I need to go understand. Thanks again.

chuckroast · Friday at 12:00 PM

chuckroast said:
The calculation is easy enough to follow but I still have questions I need to explore:

If the calculation above is correct, then my use of 0.5g/l of NaOH seems like real overkill

I would love to see the derivation of this calculation rather than just the mechanical maths

Not asking you for that, just ruminating on what I need to go understand. Thanks again.

So, with little help from my AI friend, I now understand the underlying rationale for these computations (mostly).

My 0.5g/l would deliver a pH of 12.1 in liter of pure water.

As noted above my @Raghu Kuvempunagar, further dilution of the D-23 should not much affect the resulting solution's pH.

Interestingly, if you do this calculation for FX-1 using the molar weight of 106g/mol for Sodium Carbonate, you get a pH of about 12.37 - close enough to what I've been using with lye.

The interesting question now becomes: Would reducing the amount of NaOH (or Sodum Carbonate) to get the pH down to the "9.5-ish sweet spot" better promote edge effects, I wonder. That is, am I currently too alkaline to see those effects in a pronounced way?

Donald Qualls · Friday at 1:25 PM

chuckroast said:
My 0.5g/l would deliver a pH of 12.1 in liter of pure water.

Buy you're not adding this to pure water -- your solution is already alkaline due to the sodium sulfite, so in fact you're creating a buffer system of sorts; your pH will be somewhere between that of original D-23 (8+?) and your sodium hydroxide reference at 12+. I don't know the chemistry math well enough, but you've got 100/10 = 10 g/L of sodium sulfite and 0.5 g/L of sodium hydroxide -- someone ought to be able to calculate the pH (without the metol) of that buffer...

chuckroast · Friday at 1:30 PM

Donald Qualls said:
Buy you're not adding this to pure water -- your solution is already alkaline due to the sodium sulfite, so in fact you're creating a buffer system of sorts; your pH will be somewhere between that of original D-23 (8+?) and your sodium hydroxide reference at 12+. I don't know the chemistry math well enough, but you've got 100/10 = 10 g/L of sodium sulfite and 0.5 g/L of sodium hydroxide -- someone ought to be able to calculate the pH (without the metol) of that buffer...

Ach ... right. I'll see if I can figure this out but I suspect you have to take the molar weights and proportion of each alkaline component and add them to reach the actual final pH.

Alan Johnson · Friday at 6:50 PM

Considering that the measured pH of 5% sodium carbonate solution is 11.6, not the 12.37 calculated, it is unlikely that any calculation for the 3 component metol sulfite hydroxide mix will get near the true value and it may be easier just to proceed experimentally.
Also if you look up the Altmann Henn acutance measurement experiment, the acutance increases with increasing pH.

Raghu Kuvempunagar · Friday at 10:41 PM

chuckroast said:
The interesting question now becomes: Would reducing the amount of NaOH (or Sodum Carbonate) to get the pH down to the "9.5-ish sweet spot" better promote edge effects, I wonder. That is, am I currently too alkaline to see those effects in a pronounced way?

No idea where this 9.5 is sweet spot for edge effects came from. At pH of 9.5, dilutions 1+9 and 1+14 will result in very severe underdevelopment.

koraks · 2025-06-28T02:55:25-0400

chuckroast said:
Ach ... right. I'll see if I can figure this out but I suspect you have to take the molar weights and proportion of each alkaline component and add them to reach the actual final pH.

If only it would be so simple. Equilibrium reactions will balance the pH at some point that you cannot predict linearly like this. AFAIK there's no "layman's approach" to theoretically predicting the pH of a fairly complex mixture like a photographic developer. The feasible alternative is to get some pH strips or a pH meter and just do it experimentally.

Alan Johnson · 2025-06-28T03:27:02-0400

You get quite deep in the weeds here because the word acutance has two meanings, the gradient at a knife edge measured with a microdensitometer and also the apparent visual sharpness including both the gradient and the adjacency effect.P212-214 here:

Controls in black and white photography : Henry, Richard J. (Richard Joseph) : Free Download, Borrow, and Streaming : Internet Archive

270 p. : 28 cm

archive.org

chuckroast · 2025-06-28T08:33:49-0400

Raghu Kuvempunagar said:
No idea where this 9.5 is sweet spot for edge effects came from. At pH of 9.5, dilutions 1+9 and 1+14 will result in very severe underdevelopment.

Someone upthread suggested this? Perhaps I misunderetood.

Milpool · 2025-06-28T09:00:00-0400

The effect of pH on edge effects for a metol-sulfite developer depends a lot on the concentration of metol. At moderate levels edge effects increase as pH increases. As the concentration is reduced peak edge effects occur at decreasing pH values (above which edge effects decrease). At a metol concentration of 0.2g/l the “target” pH is around 9.6. For 0.5g/l it would be somewhat higher, suggesting the use of metaborate or carbonate would be appropriate. Etc.

It should be noted edge effects are not acutance as traditionally defined (see Perrin, Altman/Henn etc.). Edge sharpness is the gradient at a hard edge while edge effects are a contrast effect at hard edges which can have an impact on the perception of sharpness (this is what a conventional or digital unsharp mask does). If edge effects are too pronounced or spread too far they can degrade edge sharpness and resolution. Granularity is also important.

Alan Johnson · 2025-06-28T12:05:31-0400

FX-1 TEA semi-stand developer

FX-1 is the highest acutance developer of all but with a pH about 11 it is a bit grainy.I replaced the carbonate B solution by dilute TEA giving a pH about 9.5. A-Metol 5g, Sodium sulfite 50g, Water to 1L B-TEA 200ml, water to 1L For use take 1 part A, 1 part B, 8 parts water Develop 4-5...

www.photrio.com

I found that buffering FX-1 to pH 9.5 made it into a semi-stand developer with a long development time.
At that time I was using only a flatbed scanner so the conclusions relating to edge effects are not as clear as they might be.

MattKing · 2025-06-28T13:45:34-0400

Alan Johnson said:
You get quite deep in the weeds here because the word acutance has two meanings, the gradient at a knife edge measured with a microdensitometer and also the apparent visual sharpness including both the gradient and the adjacency effect.P212-214 here:

Controls in black and white photography : Henry, Richard J. (Richard Joseph) : Free Download, Borrow, and Streaming : Internet Archive

270 p. : 28 cm

archive.org

@Alan Johnson ,
Technically, I think it is more correct to say that acutance is the objectively measurable gradient at the knife edge, while apparent sharpness is a primarily subjective function arising due to a number of factors - acutance, macro contrast, micro contrast, resolution and factors like adjacency effect - of which acutance is probably the most important.
Some people use acutance and apparent sharpness interchangeably, but IMHO that is the result of mistakenly conflating a primarily objective measurement with a predominant subjective function.

Chemistry: On Futher Dilution Of D-23 And Lye

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Controls in black and white photography : Henry, Richard J. (Richard Joseph) : Free Download, Borrow, and Streaming : Internet Archive

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FX-1 TEA semi-stand developer

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Chemistry: On Futher Dilution Of D-23 And Lye

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