D-23 developer magic

D23 Developer and Replenisher

I am working my way through John Finches book “The Art of Black and White Developing” 5th edition, and another simple to make, long lasting developer John recommends is the classic 1940’s D-23.

Two ingredients are all that is needed and as John points out, you can make it with teaspoons if you want.

D23 formula.

Metol7.5g (2 and ¾ teaspoons)
Sodium sulphite100g (4 Table spoons + 1 teaspoon)

WARNING: Do not use the wives table and teaspoons out of her kitchen but buy your own set of measuring spoons ????

Fill a jug with about 700ml of warm water (50 degrees C) and add a small pinch of the Sodium Sulphite to rid the water of oxygen before adding the Metol. Metol will oxidize and become useless unless you do this small step first.

Mix well into solution the Metol then add the Sodium Sulphite, mixing that into solution also.

Top up your container with water to 1000ml (1 litre).

That’s it, simple or what.

But next we create magic

Replenishing D23 creates a developer that like a fine wine, matures and gets better with age.

You make the replenisher just like the D23 above adding Sodium metaborate last.

We only make 500ml of the D23 replenisher making a fresh 500ml once used up.

D23 Replenisher formula.

Metol5g (1.5 teaspoons)
Sodium sulphite50g (2 table spoons + ½ Teaspoon)
Sodium metaborate10g (2 teaspoons)

Label your container bottles carefully so’s not to get them mixed up.


First develop 3 films, either 35mm or 120 rolls, pouring the used D23 developer back into is bottle.

This Is via the Stock solution and you cannot replenish a watered-down version.

After the 3rd film is done mark the bottle to where the level of developer sits.

Now develop your 4th film and before pouring the used D23 developer back into the bottle, measure out 22ml of the replenisher and pour that into the D23 bottle. Not top up the D23 developer bottle to the mark you made earlier. You should have some of the D23 still in your container. This is good and just dispose of that as you normally do.

Do this with each film you develop, adding 22ml replenisher then topping up with the old developer.

Do this for say 30 or 40 films.

After this get rid of ¾ of the matured developer and top the bottle up with fresh D23.

This will be matured by the old developer you left in the bottle and you continue with developing a roll, adding 22ml of replenisher then topping up with the used D23.

Some say D23 is a low contrast developer.

This is not so. If you want more contrast then develop longer, use a higher developing temperature than the 20 degree C or agitate the developer tank more. Or a mix of all three until you get the negatives that suit your needs.

But if you have your development times down, negatives from Replenished D23 are easy to print via your enlarger, adding contrast via filters if needed, or scanning on your computer.

To be continued….

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