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Sunday, May 11, 2014

Blend Caffenol

Important update at the end!

Starting by preparing Caffenol black and the Orange developer as listed below,


I repared that both have the same pH value and if I mix them, then the result would have the same pH value and by mixing them in a fifty-fifty proportion the final solution will have half the amounts of chemicals per liter and the recipe would be then:
1000 ml water
10 g soluble cheap coffee
28 g Sodium Carbonate*
5 g of Vitamine C
What changes then? The developing time, because coffe and Vit. C are superadditive. In fact the developing time drops to 12 or 15 minutes. The first roll I developed it in just 10 minutes but the film is slightly underdeveloped. Next time I will try 15 minutes. To the 1 liter developer I added then a pintch of Potassium Metabissulfite to see if it helps to preserve the solution for reuse. I will test this today.

Another suggestion is to work with a lower pH reducing the amount of Sodium Carbonate. Developing time will increase but the grain will be finer.

Farmer house
Blend Caffenol, Shangai GP3, 10 minutes semi-stand development
* Note: I calculated wrong (23 g). This was a lucky mistake, because in reality we only need 20 g/Liter of Sodium Carbonate. Please update the recipe as follows:

1000 ml water
10 g soluble cheap coffee
20 g Sodium Carbonate anhydrous
5 g Vitamine C

Mixing order as given in the recipe. The pH value should stay in about 10,4-10.6. Developing time is 15 minutes for the first roll. You may reuse at least within 24h, more time is not known yet.

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