Darkroom Digest: Exploring D-23 Split Bath Large Format B&W Film Development

June 20, 2017  •  1 Comment

What is D-23 black and white film developer and why do photographers use it? I will help answer those two questions in this article for you, in hopes that you may find a use for it in your darkroom.  

The famous photograph by Ansel Adams "Winter Sunrise from Lone Pine" was exposed on Isopan film and developed in D-23.  "I used my 8x10 Ansco view camera with the 23-inch component of my Cooke Series XV lens with a Wratten No. 15 (G) filter. The film was Isopan, developed in Kodak D-23" - Ansel Adams

As the title of this article suggests, I will be sharing my thoughts as well as my process for using D-23 as a split-bath developer.  When I think about split-bath development, I immediately think variable contrast development and the classic zone system.  

If you are reading this article, then you may be interested in my Introduction to B&W Darkroom Photography video workshop or my Split-Grade Darkroom Printing eBook

In simple terms, Bath A is where the development agent (Metol) is located and in Bath B is where the alkali resides and the remainder of the development is carried out.  In theory, one can change the contrast of their negative by varying the amount of time in Bath B.  But, is this the case for split-bath D-23? Read the details below to discover how this happens with D-23 and you might be surprised by the information. 

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I primarily use D-23 on my negatives when I want excellent separation of shadow values and brilliant highlights. I can alter my tray development times to increase contrast and density for my platinum and AZO printing, or I can improve my shadow details by altering my development times in the two different solutions.  I find D-23 to be a very versatile developer whether you and making straight silver gelatin contact prints or enlargements or you need more contrast and density for alternative printing processes such as platinum and AZO.    

I have created a short list of why I like D-23: 

  • D-23 has only 2 ingredients making it very simple to mix in the darkroom and it is highly effective.  
  • D-23 is a fine grain developer with excellent tonal separation, good film speed and it produces very clean negatives.
  • D-23 is incredibly easy to make.  You can mix it fresh from powder every time making it a great choice for any photographer that is not developing on a regular basis.
  • I think D-23 is a good developer to have on hand for large format photographers because it can be tailored to each negative that is developed. 
  • D-23 can be diluted 1:1 making it even cheaper to use. By diluting to 1:1, you can get longer development times which comes in handy when doing development by inspection.  
  • D-23 is a slightly slower developer, which means it has good compensation and less risk of "runaway" highlight values.  I find this useful for my higher contrast scenes.   
  • One of the biggest benefits in certain scenarios is my ability to expose my large format sheet film at box speed.  For example, being able to expose HP5+ at EI 400 can be a big advantage in some cases.  


Black and white film developers typically consist of three main components: developing agent (e.g., Metol), alkaline agent (e.g., borax) and a means to delay oxidation of the developing agent (e.g., sodium sulfite). 

Metol along with phenidone (a newer agent) and hydroquinone are common black and white developing agents. Metol is an organic compound and a colorless salt.  Metol is known to be a good choice for continuous tone and has been widely used in commercial formulas for many years before Kodak discontinued it. Metol is a highly versatile developing agent and a standard that I keep in my darkroom.  


Developer (Solution A)

  • Metol.....7.5g
  • Sodium Sulfite.....100g
  • Water to make 1 liter 

Process to Make Solution A

  • Heat 500ml of distilled water to 52C/125F
  • Dissolve 7.5g of Metol separately in small amount of distilled water
  • Add the dissolved Metol to 500ml of 52C/125F water
  • Dissolve 100g of Sodium Sulfite in small amount of distilled water
  • Add the dissolved Sodium Sulfite to the 500ml of 52C/125F distilled water with Metol 
  • Add distilled water to make 1000ml 

Process to Make Solution B

  • Dissolve 2g of Borax in 1000ml of distilled water heated to 52C/125F 


1 liter of developer solutions can process approximately 800 square inches of film before discarding it.  That would equal about 40 sheets of 4x5 film, 20 sheets of 5x7 film, 10 sheets of 8x10 film, and 5 sheets of 11x14 film.  In other words, you can mix up one liter of developer for your film development session and process a lot of exposures.  I usually only create a handful of exposures for a days work anyway, so I have more than enough developer for my session.  I use fresh developer for each session and discard it afterward. You can cut the formula by 50% to make 500ml if needed.  


I have found that Ilford HP5+ and FP4+ develops to my satisfaction with divided D-23.  I frequently use HP5+ sheet film in my 8x10 and 11x14 large format view cameras and FP4+ in my 4x5, 5x7, and 8x10 cameras. I process my films in trays, either in my regular darkroom, on in my film changing tent when I am on the road. 

I have three trays lined up (Solution A - Solution B - TF-4). When I am working in my regular darkroom, I have another tray of distilled water to place the freshly developed negative before moving to the film washer.  If I am on the road, I just wash my films by placing them in trays and letting them soak and periodically agitate for about an hour until they are fully cleared.  

Based on the contrast of my negative being developed, normal, expanded, or contracted, I vary my times in Solution A and you will notice that my time in Solution B remains constant at 3 minutes.  

Below are my personal development times for FP4+ and HP5+:

  • Normal:  10 min in A + 3 min in B
  • N+1: 12 min in A + 3 min in B
  • N+2: 15 min in A + 3 min in B
  • N-1: 8 min in A + 3 min in B
  • N-2: 6 min in A + 3 min in B

Most divided bath developers have the developer in Part A and the accelerant in Part B.  Because of the amount of sodium sulfite in Solution A, your film is actually being developed without the need for an accelerator.  Now that is pretty amazing.  Then when you move your sheet film to Solution B (borax), this is where the magical compensating effect happens because the developer agent (Metol) is quickly exhausted in the high values (dense areas), and the lower values (shadows) will continue to develop.  This basically means that you are developing for your high values in Solution A and shadow values in Solution B.

It is possible to use the development by inspection method on a negative by negative basis, or I just put in the time and found the standard times that work for my style of photography that doesn't require the inspection approach.  

You can develop a single sheet of film or multiple sheets at a time using the shuffle method. 

Your agitation method will impact your development times and negatives, so keep this in mind when establishing your development times.  

Story's Creek Schookhouse at Alley Spring & Mill (5x7 Large Format Negative)Story's Creek Schookhouse at Alley Spring & Mill (5x7 Large Format Negative) For normal and expanded development (N and N+), I place a sheet of film in Solution A and continuously agitate for the first 30 seconds and then 5 seconds every 30 seconds for N development and 10 seconds for N+1 until the development time is completed for this step.  I slowly and gently rock my tray for the entire 3 minutes in Solution B.  The negative to the left is a sheet of 5x7 FP4+ developed for N+1.  The building in the scene is a historic white schoolhouse.  

For contracted development, I place the film in Solution A and agitate for 10 seconds and then 10 seconds per minute until the time is completed for this step.  I then place my film in Solution B and give in just a single rocking motion to ensure the film is submersed.  For N-1, I gently rock the tray for 5 seconds every minute and for N-2, I don't agitate the film at all beyond the initial entry in the tray.  

After you start developing your negatives and review them, keep in mind the following two variables and you can really dial in your process.  If you want to increase the overall density and contrast of your negatives, then extend your time in Solution A.  If you need more shadow detail, process your film in your normal Solution B time, then place the film back in Solution A for 15 seconds, and then to back to Solution B for another period of time.  Start with times in the range of 1 to 3 minutes and evaluate your negatives.   

After development, I move immediately to TF-4 archival fixer which effectively eliminates the need for a stop bath and hypo-clearing agent and also significantly reduces my washing times.  I can even develop my negatives on the road in my Harrison Dark Tent which makes this a very user friend solution in my regular darkroom or in my mini-darkroom in my van.

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Have fun developing your films and send me an email if you try my method and let me know how things are working out for you. 

-Tim Layton 

The Darkroom Underground is your analog photography magazine produced on a quarterly basis serving photographers, artists, collectors, and readers around the world. Publications are released on Jan 1st, Apr. 1st, July 1st, and Oct. 1st.  The Darkroom Underground publishes a balance of technical and creative articles in every issue along with featured photographers and their portfolios. We are pleased to offer editorial from internationally recognized photographers and writers and also publish articles and portfolios from our readers. 

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Tim Layton
B&W Fine Art Analog Photography
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© Tim Layton Sr. | All Rights Reserved



1.Susan Huber(non-registered)
Thank you for this post! Often I have wait til I get home to see what I did with my lf film. Now, I can use my battered Harrison tent for this on the road! Having a simple developer that can be mixed is easier as I do not develope much...
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