Fine Art Photography
4x5, 120, and 35mm Film

Developing Black and White Film with D-23


During 2020, Kodak’s XTol developer production became plagued with issues. Certain lots of XTol simply wouldn’t develop film after being mixed. Kodak can also be very difficult to work with and thus getting your money back probably costs more than the $10 a bag of XTol costs here in the USA. Given these issues with XTol, I began looking around for a new black and white developer. Previously, I’d tried ID-11 (D-76), Perceptol, and Microphen, so it was time to try something different. I bought some Ilfotec DD-X and felt the results to be good, but nothing that stunned me — except when it comes to Delta 3200. I shot Delta 3200 at 6400, developed as if I had shot it at 12,500 and those results were spectacular.

I had seen references to D-23 before and had seen some absolutely stunning images developed with D-23 (from Ansel and others, see: and this had piqued my interest. That said, ready made D-23 is something that I had a hard time finding. You can buy direct in the USA from Photographer’s Formulary. Here are those links:

Considering that you need D-23 and DK-25R (more on this later) to get any economy out of D-23, the above option is fairly expensive when you consider that 6+ months of XTol costs $10. The other option that you have is to mix your own D-23, but this involves buying raw chemicals and sounded difficult. Given this, when I had initially seen D-23, I gave up on the idea, but in early 2021, after getting bit by the XTol issues (blank film rolls out of the tank are not fun) and not being super impressed by DD-X, I decided to give D-23 a go! For me, I love the results that I get with D-23! So this blog is my take on how to do D-23 yourself in a replenished manner, with or without rotary processing.

How to Mix D-23 and DK-25R Yourself

So with D-23, you can mix 1L of stock chemistry and then use it as stock and reuse it or dilute it to 1+1 or 1+3 and use it one shot. All of these formulations will yield slightly different results, but diluting the stock means that you run through developer much quicker than if you keep reusing stock.

To reuse D-23 stock, you need to replenish after developing film and that’s where DK-25R comes in. For each roll of film that you develop in D-23 stock, you will add 22mL of DK-25R back to your D-23. I’ll talk through those details in the next section.

Mixing these chemicals is relatively straightforward and if you have ever mixed a powered developer from a bag before, then this is pretty much the same thing. The only difference here is that you have to weigh out individual chemicals to add to your developer instead of having a bag or two of pre-weighed chemicals.

D-23 Formula:

  • Metol – 7.5g
  • Sodium Sulfite – 100g
  • Water to Make 1L

DK-25R Formula:

  • Metol – 10g
  • Sodium Sulfite – 100g
  • Sodium Metaborate – 20g
  • Water to Make 1L

In the USA, you can buy these chemicals at Art Craft Chemicals and here are non-affiliate links to the specific chemicals:

As with any chemicals, you should read the MSDS data sheets and know what you are getting into. Some people are very sensitive to Metol and have problems if their skin comes into contact with it or if they breathe it in. If you wear gloves, wear a dust mask, and practice proper safety precautions while mixing these formulas, you should have no problems getting D-23 and DK-25R safely mixed up.

So let’s dig in! To mix up D-23:

  1. Fold two sheets of paper in half lengthwise.
  2. Get a spoon for the metol and a spoon for the sodium sulfite.
  3. Place a sheet of paper on a scale, tare the scale, and measure out 10g of metol.
  4. Place the second sheet of paper on the scale, tare the scale, and measure out 100g of sodium sulfite.
  5. Start with 700mL of water at 52 C / 125 F.
  6. Add a pinch of your previously measured sodium sulfite.
  7. Add all of your metol and stir until dissolved. Your solution should not turn pink at this point. If your solution turns pink, properly dispose of it and start over.
  8. Add the rest of your sodium sulfite and stir until dissolved.
  9. Add water to bring the solution to 1L and store in a 1L bottle. It’s best to let this sit for 24 hours before using it. You can use it immediately, but it has more time to settle if you give it a day.

Now that you have D-23, let’s mix 1L of DK-25R:

  1. You can reuse the metol paper and sodium sulfite paper and their spoons from the previous step.
  2. Get a third sheet of paper folded in half lengthwise and a new spoon for the sodium metaborate.
  3. Place this sheet of paper on the scale, tare the scale, and measure out 20g of sodium metaborate.
  4. Measure out 10g metol.
  5. Measure out 100g sodium sulfite.
  6. Start with 700 mL of water at 52 C / 125 F.
  7. Add a pinch of the sodium sulfite.
  8. Add the metol and stir until dissolved. Again, the solution should not turn pink. If it does this, time to start over.
  9. Add the rest of the sodium sulfite and stir until dissolved.
  10. Add the sodium metaborate and stir until dissolved.
  11. Add water to bring the solution to 1L and store in a 1L bottle. As with D-23, it’s best to let this sit for 24 hours before using it as well.
Chemicals for DK-25R ready to be mixed
Bottled Solutions of D-23 and DK-25R

So now you have 1L of D-23 and 1L of DK-25R and you are ready to go! This chemistry will develop a lot of film over a long period of time. One year later, I’m still getting good results from this first batch!

How to Develop with D-23 and DK-25R

Developing with D-23 is very straightforward. This guide assumes you have some understanding of developing black and white film already.

I start by pouring my 1L of D-23 into a 1L graduated cylinder at which point I can take the temperature of the solution.

I then take that temperature and use the temperature/time conversion feature of the Massive Dev Chart Timer App to determine what time I’m actually going to develop at. Given that I’ve now moved to rotary processing and I don’t usually do a pre-rinse, I also set my recipe to automatically shave 15% off the total development time to compensate for the lack of pre-rinse. This is specific to rotary black and white development and not to D-23.

If you are using brand new D-23, you should develop the first two to four rolls without replenishment. After you have developed the first two to four rolls in stock without replenishment, start using the following replenishment method.

Replenisment Method: Now that I know for how long I’m going to develop, I’m almost ready to go. I now measure out 22mL/roll of DK-25R into another graduate so that I have my replenisher ready. So effectively, if I do 1 roll, I usually measure out ~25mL . If I do 2 rolls, I measure out closer to 50mL, 3 rolls, ~70mL, etc. You just have to hit 22mL/roll and you’ll be golden.

Now it’s time to pour the D-23 into the tank and put the tank on the rotor and start the timer and the rotor. If you’re not doing rotary, time to start the timer and begin agitations.

While the film is developing, pour the DK-25R back into the 1L graduated cylinder and have a waste container ready to go.

When the film is done developing, pour the contents of the tank into the 1L graduated cylinder up to the 1L line and pour any remain tank contents into the waste container.

That’s it! Proceed with stop bath or a water stop bath and moving onto fixing, rinsing, photo-flo, etc. You’ve now replinished your D-23 and will get a lot of mileage out of this solution.

D-23 Recipes and How to Determine a Starting Point

Determining how long to develop black and white film for in a particular developer is usually pretty easy, thanks to the Massive Dev Chart. The Massive Dev Chart has several times for D-23 in a variety of solutions for a handful of common films. That said, the Massive Dev Chart is not as complete for D-23 as it is for XTol or D-76 and so there is a lot more guess work for using D-23. I’ve read that you can start with a D-76 time and add 20% to get to the proper D-23 time. That said, don’t go compare notes for D-23 and D-76 when developing Ilford HP5+ in stock solution at ISO 400 or you’ll find that both developers call for 7.5 minutes! So it’s not as cut and dry as one would hope. But I can tell you that I have done this D-76 time + 20% method for a few films and found it to be quite workable. I’ve also searched flickr to see if others have posted their D-23 times for certain films. D-23 does require a little bit of trial and error in this regard, but I did want to share the film recipes that I’ve been using where they haven’t been published in the Massive Dev Chart:

FilmDevelopment TIme (Stock Solution at 20C)
Eastman 5363 at ISO 258.5 minutes
Rollei RPX 400 at ISO 40010.5 minutes
CatLabs X Film 80 at ISO 8011.5 minutes
Rollei RPX 100 at ISO 1009.5 minutes
Eastman XX (5222) at ISO 2008 minutes
Ilford Ortho Plus at ISO 809 minutes 36 seconds

I would consider the above as starting times, but do note, that I have had success with those films at those times. I am not measuring the developed negatives with a densitometer, so I cannot speak with that degree of authority. Your mileage may vary, but I have found the above quite reasonable and the CatLabs X Film 80 in D-23 is extremely nice!

Example Results in D-23 and Common Films

Kodak Tri-X in D-23
CatLabs X 80 in D-23
Delta 100 in D-23
Eastman XX (5222) in D-23
Ilford FP4 in D-23
Ilford Ortho Plus in D-23
RPX 100 in D-23
RPX 400 in D-23
Ilford FP4+ in D-23, 1 year after the initial mixing