"Shelflife" oc affenol ?
Dose anyone know how long caffenol(with or without vitamin C) can be kept after mixing?
P.S. For those who do not know, caffenol is simply instant coffee+sodium carbonate, with or without vitamin C. The fresh mixture can be used as a film developer.
it might depend on the coffee used. some instants have more
robusta than others ...
that said i have 3? L of caffenol in my darkroom that
still works ( made in august i think)
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artwork often times sold for charity
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Most users advise using the caffenol within an hour or two of mixing it, if only to avoid having something that malodorous hanging around the darkroom for too long! Jnanian, however, can make it seem like rodinal, the everlasting magic potion...he's that good. I use it occasionally as a one-shot within an hour of mixing, but I must admit I've never really tried to save it and use it again. The one time I mixed up a batch and put it aside, it grew mold (I kind of forgot it in the corner ).
the difficulty with answering the question is that Caffenol is not just one developer - everyone's brew will be different depending on the coffee used, soda used, ascorbic acid used (some people grind up Vitamin-C tablets, others use lab-grade ascorbic acid, and others everything in-between I'm sure), measuring regime used (some are spooning, some are weighing), and so on; plus of course nobody really knows for sure what the "other" developing agent is (although there seems a vague consensus that it's probably caffeic acid).
Any and all the Caffenol recipes have been empirically developed and anecdotally reported; It's not a laboratory-tested product with known parameters.
So maybe a brew will last an hour, or maybe it'll last 6 months; but nobody knows at what level of activity.
There are plenty of reports that it lasts "ages" or "months". But do you want to use a 6-month old batch on a roll you really want not to mess up and find it's dead? Or changed characteristics?
[Don't get me wrong, I'm not anti-Caffenol, I like it and it almost always produced great results for me, but I found it too much faff to make up every time I wanted to develop a roll & I didn't want to use it other than one-shot for the reasons given above]
Thanks to all 3 responders. The reason I asked the question is that I made a batch of "homemade silver emulsion" only to realize that I was out of developer. And I was out of sodium sulfite. So I could not make my own "standard" developer. As a last resort I made Caffenol with ascorbic acid, as described in APUG articles. Results were some of the best I have seen with "homemade" silver emulsions. So, I got excited and want to make lots of Caffenol. But I think I will make it fresh for each developing session.
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You can weigh the quantities you need and mix them, and storing them pre mixed powder, and often when you need only add water
I have used Caffenol as a paper developer and in open trays it loses power pretty quickly. Usually I mix a 1 L batch and split it in half to have enough developer to last for an 8x10 printing session. If I was using it for film I would definitely mix fresh, it's not worth the risk of getting bad negatives.
Certainly one way of shortening the process is to make up a "stock" solution of 5% carbonate (54g/1000ml is in Reinhold's recipe for C-M, though anywhere between 4% and 6% seems to be fine) and then the Ascorbic acid and coffee can be mixed straight into that.
Originally Posted by Xuco Martin
The thing I found most of a pain in the arse was the temperature change when making up the brew using crystal soda (x2.7 by weight in place of anhydrous), & having a stock sol'n of alkali helps with that too ... Although, of course, if I were not congenitally lazy, I could have measured the temp change and started off with water at a temp that allowed for it ...