Coffee Ascorbate Developer

This recipe exists in two forms: one that calls for Ascorbic Acid, and one that calls for Sodium Ascorbate. It is worth pointing out that Ascorbic Acid only works as a developing agent if it is neutralized so as to no longer be an acid. The way to do this is to add an equivalent amount (by number of mols) of a strong base, Sodium Hydroxide. This will essentially convert the Ascorbic Acid into Sodium Ascorbate. In this form, it works as a developer. Note that the Sodium Ascorbate formula does not call for Sodium Hydroxide, because there is no acid present to be neutralized.

Either formula works the same. Ascorbic Acid tends to be easier to find, and with the hydroxide, works fine.

The replenisher contains Sodium Hydroxide, in order to keep the developer basic so that it remains effective as it is reused.

 

Formula #1: using Ascorbic Acid

	Developer	Replenisher
Ground Coffee (Folger’s French Roast*), grams	44.0	88.0
NaOH (to neutralize the Ascorbic Acid), grams	9.1	25.7
Sodium Sulfite Anhydrous, grams	90.0	90.0
Ascorbic Acid, grams	40.0	80.0
Sodium Carbonate Monohydrate,, grams	52.5	52.5
Potassium Bromide, grams	2.00	2.00
final volume, liters	1.00	1.00

Formula #2: using Sodium Ascorbate

	Developer	Replenisher
Ground Coffee (Folger’s French Roast*), grams	44.0	88.0
Sodium Sulfite, Anhydrous, grams	90.0	90.0
Sodium Ascorbate, grams	45.0	90.0
Sodium Carbonate Monohydrate, grams	52.5	52.5
Potassium Bromide, grams	2.00	2.00
Sodium Hydroxide	—–	7.50
final volume, liters	1.00	1.00

 

Bring 1 liter of water to a boil. Add coffee, boil 5 min, turn off heat, let sit 15 min.

Filter out the grounds (several layers of cheese cloth in a large funnel works pretty well; you may need to run it through twice and take advantage of the settling that occurs.  Coffee filters tend to be MUCH too slow!).

Let cool to about 50°C.

Add the Sodium Sulfite.

For Formula #1 (Ascorbic Acid), add the Sodium Hydroxide, stirring to dissolve.

For both formulas, add, in order, the Ascorbic Acid / Sodium Ascorbate, the Sodium Carbonate, and the Potassium Bromide (and for the Sodium Ascrobate Replenisher, the Sodium Hydroxide).  Stir continuously to make sure that each is dissolved before adding the next.

Add water to the final volume.

Process 5 min @20°C

Replenish 100 ml per 100′ of 16mm film (1 ml per foot)

*a note on coffee: this recipe calls for regular ground coffee that has to be brewed, not for instant coffee.  It calls for a specific brand only for reproducibility, because it worked well with that particular brand.  Please feel free to use any kind of ground coffee!  For consistent results, it’s probably a good idea to settle on one, whatever that is.  Also, rumor has it that Robusta beans are better for developing than Arabica.  Generally, if it doesn’t say which kind of beans it is (and it usually doesn’t) the cheaper the coffee, the more likely it is to be Robusta.