Since talk about coffe and ascorbate developers surfaced on the Net, they have been surrounded by a lot of myths.
Quite funny is all the exaggerated statements about the fact that coffe is used as a developer, especially from places where coffe is still seen a something exotic to drink. A lot of talk about developing the films in coffee, and then drinking the stuff!
As usual just tall stories, from people that know little about both coffe and developers....
However, one statement has stood out from the beginning :
Vitamin C will not keep. So it has to be used within half an hour from mixing and then be discarded immediately. That's what they all say.
Personally I challenged this from the word go, and developed the technique of Stock solutions - that has just recently been picked up by others.
Stock solutions will keep, if the ingredients are dissolved, and kept in tree separate bottles at 3X concentration, the stock solutions will keep easily for two months, and in use one just measure out 1/3 of the required volume from each bottle, eventually add KBr from the 10% stock solution....
But whatabout mixed developer, all ready to go?
It will keep. You can rest assured you can keep it overnight and use it the next day, easily.
More, no need to discard the developer after developing one film, either.
I now use my Kaffenol 327 this way: I mix 320 ml of developer, then I load two tanks, one 135 film in each.
I first develop the first film and have settled on 16 minutes at 20 degree centigrade as a good starting point.
Then I collect the used developer, and add one or two teaspoons of instant coffe, tops up the volume to 320 ml (11 fl.oz.) and develop the second film.
One can even develop one film in one night, and then wait until the next before developing the next film.
If anything the second film seems more contraty than the first, I probably could get away by replenishing the developer with just one teaspoonful of coffe.
I intend to test out with 3 films developed in one and the same night, repleneishing with one teaspoonful of coffe per film, topping up volume as needed.
Some have been complaining about the cost of Kaffenol, well, there you have it, a safe and surefire way of slicing the cost in half!