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Looking for a versatile developer that'll cope with any film and provide rock solid dependability? Maybe you should be trying D-23, and even better, use it replenished!

D-23 has been around since the 1940's. Of the many people who used it Ansel Adams is one of the most famous. It's controllable, fine grained, clean working, and forgiving of high contrast. And it's so easy to make. Here's a way to use it that's almost never mentioned but let me tell you, it's amazing!
D-23 was formulated to be a better D-76 and in fact even has the same development times. According to Anchell and Troop's
The Film Developing Cookbook it was designed to be especially reliable as a replenished developer, the type of reliability commercial labs needed for the thousands of films they processed. D-23 in and of itself was very stable and didn't change activity like D-76 did over time, and it had similar fine grain to D-76, providing good shadow detail with well controlled highlights. D-23 excelled in those contrasty situations where other developers might run away and burn out the highlights. Furthermore, it is as simple as it gets, consisting of only two chemicals, metol and sodium sulphite.
Chemical Amount
Water 50C 700ml
Metol 7.5g
Sodium sulphite 100g
Water to make 1 Ltr
If mixing this up don't forget to add a small pinch of the sulphite to the water before fully dissolving the metol. This stops the metol from oxidizing. Finally, dissolve the rest of the sulphite and make up to 1 litre - metol won't dissolve if you add all the sulphite before it.
D-23's soft working nature and forgiving personality is complimented by a versatility that earns its place in any darkroom. It can be used as a stock developer for fine soft grained long tonal range photographs, with a similar look and times to D-76, or it can be diluted up to 1+3 for a different effect. These higher dilutions change how D-23 works on the film, moving from that fine grain developer (stock) to a sharper developer (1+1) to an acutance and compensating developer (1+3). As you dilute it, just like D-76, the long tonality reduces so why not try them all and choose your favourite dilution.

Some people who try D-23 think it's too low in contrast. That's just not right. What they've done is under developed with it. They're possibly used to developers like D-76 that increase in contrast quickly, too quickly sometimes! However, D-23 like any developer of this type, uses longer development to increase contrast by pushing up the highlights more gradually. If you want more punch from your D-23:

  • Develop for longer, or
  • Increase agitation. (Normal agitation is 5 seconds every 30 seconds) or
  • Increase temperature.
  • Even a combination of all three things.

These techniques will increase your negative contrast and give you the range you want. It's so simple a developer yet so very versatile. Frankly, it might be the best developer you'll ever use!

Many suggest that the best dilution of D-23, like D-76, is 1+1 but not me. Oh no! The "secret sauce" of using D-23 is with replenishment! Read on, it's magical.

Replenished D-23

Replenishment is a very reliable technique for using developers. In the past, when films were developed in deep tanks and/or commercial machines the developer was "topped up" with a special replenishment formula. Formulas were designed to allow the developer to continue working consistently and dependably for literally
thousands of films. With the replenisher below you can develop 30 films in a litre of D-23.

  1. Mix up and bottle separately one litre of D-23 and one litre of replenisher (DK-25R, formula below).
  2. Use the D-23 at full strength for three 36 exposure or equivalent films pouring the used developer back into the stock bottle after each session (you can't use replenishment if you dilute the developer so always use full strength).
  3. Now, mark the top of the solution on the D-23 stock bottle, I use a permanent sharpie. The mark will be near the top because it should be nearly full, remember you've been pouring the used developer back into this bottle. The sharpie mark will be used to top up the bottle after each subsequent film development.
  4. Start replenishment. After the next, and subsequent, film is developed and before you return the used developer back into the stock bottle add 22ml of the replenisher (Dk-25R formula below) to the stock bottle then pour the "just used" developer back into the stock bottle filling the bottle back up to the sharpie mark. You are now replenishing!
  5. You'll need to add around 10% to your regular D-23 development time. Some films need a little more such as HP5+ which, I find, needs around 30% more time. This time is stable and doesn't need to be increased with each film, just stick to the extra 10% or so with every film. My time, for instance, with FP4+ is 8.5 minutes in replenished D-23. It's always 8.5 minutes no matter how many films I've put through the replenished developer. Note: I do increase my development times to increase contrast on flat photographs (N+ development) or reduce it for lowering contrast. (N- development). D-23 reacts perfectly to this kind of work. Just as a starting point try 30% more development for N+1 and 25% less for N-1.
  6. If this development time get's too long for your liking then increase your development temperature. For each degree centigrade you increase your developer above 20C you can reduce dev time by 10%.

That's it! By adding 22ml of replenisher into the stock solution, and then topping the stock back up to the mark after each film you are using developer replenishment.

Do I use the developer (replenished) forever?

I don't. After 30 films (or equiv.) I discard 3/4 of the stock developer and top up the bottle with fresh made stock. Then just carry on replenishing, no need to develop the three films first.
DK-25R - D-23 Replenisher
Chemical Amount
Water 52C 650ml
Metol 10g
Sodium sulphite 100g
Sodium metaborate* 20g
Water to make 1 Ltr
*If you can't get sodium metaborate you can replace it in this formula with 14g Borax + 3g Sodium Hydroxide.
- After dissolving the rest of the chemicals calculate how much water will be needed to top up the amount to 1 Ltr.
- Then use this calculated amount at 50C to dissolve the borax followed by the hydroxide.
- Allow to sit for ten minutes with occasional stirring.
- Then add to the other part and mix.

Why not give it a try? You might find it's the best thing you've done for your photography in years.
Important: Remember, do testing before committing your prize photographs!

My development times are (for a diffusion enlarger or scanning):

PANF+ 8 minutes
FP4+ 8.5 minutes
HP5+ 10 minutes

But use these as a starting point for your own work. Click the picture below to see a video on me making D-23 and subscribe to my channel to see many more.
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Video: Making D-23

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Video: Replenishing with D-23 and making Replenisher