Like I said before, the experiments with hair dye were not successfully, leading to very weak negatives, that is to say, with fast no color development. So, I suppose the quantity of CD4 present in the hair dye solution was not enough to produce color development. And if the quantity must be larger, that is not interesting on the economic point of view. So, I have to order CD4 as component of the developer bath. Unless I discover another color developing agent present in some other think. Any ideas?
Not to fill much frustrated, I returned to the former experience, using color developer from Tetenal Colortec. I had a batch of the 3 baths of Tetenal that I prepared and already used to develop successfully some 4 or 5 color films. I just replaced now the developer bath with a Caffenol base to witch I added this time 30 ml of the prepared Tetenal color developer bath. The recipe was:
2 tsp washing soda
4 tsp Soluble coffee
30 ml Tetenal developer solution
water to make 700 ml
The temperature of the developing bath was kept at about 40 ºC, some times more, some times less because I had to poor hot water (I don't have a thermostatic bath). The developing process took 45 min, followed by the other parts, bleach-fix and stabilizer according to Tetenal Colortec.
The negative looked like this example:
The image above, after positivation with GIMP:
The same image, with a slight reduction of saturation, followed by automatic white balancing in GIMP:
The colors in the last picture are quite correct, the appearance of grain is not due to the negative but more to the automatic process in GIMP. But I am not an expert in GIMP. And I didn't care too much with the dust spots in the negative (they are digitized with a digital camera), the purpose is to get color with caffenol!