A few caffenol questions...

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pryan9

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So I've bought my ingredients and plan to start developing in the near future but I still haves some questions. My first is about using a commercial stop bath. I've seen similar questions posted on the web and the general answer ive come across is that a stop is not needed and several water washes is sufficient with an option of adding a little vinegar. My question is...CAN I just use a commercial stop bath if I want to? It shouldn't screw up the process at all should it?

I was thinking about maybe developing for a slightly shorter time since the commercial stop solution will most likely halt the developer faster than a 10x rinse cycle with vinegar.

Any thoughts?

- Pat
 
I've used normal stop solution and that acid stuff that cleans lime scale, I wouldn't worry about over-development it isn't the most active developer going
 
Personally, I wouldn't bother with commercial stop for caffenol because I wouldn't want to reuse the stop afterwards. But, it's cheap and easy to dispose of, so if you don't mind using it one-shot (many people don't) there's no reason not to.

But I also wonder if you're potentially a bit confused about the nature of stop. I know there is an interminable argument about it on the internet, so I'll try to stick to facts:

The one indisputable advantage of an acid stop is that it prolongs the life of an acid fix. Stop is both cheap and easy to dispose of. Fix is more expensive, and harder to dispose of. The trade-off there is fairly obvious.

A 10x rinse is way too much; Ilford's water-saving method for a final rinse requires only three changes of water. Two changes with 30s agitation each is more than sufficient for a "water stop" if you want to go that way. And you will not need to change the development time (with caffenol it's often "the longer the better" anyway).

Personally, the utility of stop as a method of precisely halting development in the typical day-to-day home process is vastly overstated. The difference in the time it takes to halt development is a regular source of debate, but as far as I'm concerned it's well into "angels on the head of a pin" territory - a handful of seconds at most; I've never seen a set of images that claim to show a repeatable difference between an acid stop and water stop.
 
I've used a couple of water flushes, mostly to keep my stop bath from being contaminated. I'd agree that caffenol is pretty slow-acting stuff.
 
Slow acting? Depends really. I'd say half as active as most other developers recommended dilutions, at least the Caffenol solutions I use. Between 11 and 16 minutes at 68F for most 100 - 400 films with a 1 stop push if need be. What is important is consistency, as wirh any other developer. If you use a water stop bath when getting to know for how long to develop your films, you may have to make adjustments if you switch to and acid bath later. Admittedly there will not be much of a difference, but still. Caffenol is reputed to be one stop, that is a bith of a myth. I've on several occassions developed three rolls of 120 in succession in the same soup. So you can count on it still being active towards the end of the development.
 
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What are your thoughts on "fogging" I've asked around on the internet and some say to use Potassium Bromide to eliminate this problem. Anyone have good results without an anti fogging ingredient in their solution?
 
I've done both ASA 100 and 400 without potassium bromide. 400 was quite fogged but sort of printable (enlarger, I don't have a scanner). It gets a lot better with it though!
 
I used a little bit of KBr (potassium bromide) with ASA 100 films initially, but its not needed really, at least not for 120 films. The fog is negligible, and no streaks even without KBr. For ASA 400 films I use 1 to 2 g/l depending. HP5+ works fine with 1g/l or so, whereas TMY-2 can do with 1.5g/l or more. KBr is an inhibitor, so developing times will need to be prolonged, depending on the amount needed. 10-20% typically. If you stand develop in Caffenol you need KBr no matter the film speed, or you will get uneven development, and fogging.

Other restrainers? I've not used anything but KBr, but I've heard citric acid being used. Not quite as effective it would seem, at least where fogging is concerned.
 
Iodine or iodide as a restrainer? Yes, indeed there is a group or two on flickr devoted to the subject. It works too. The genius being its readily available in table salt with iodine additives. Not tried it myself yet as the amount of iodine added to the table salt in this country is a 1/5 of what can be had elsewhere. The amount of salt would have other side effects most likely. With the addition of salt instead of bromide, Caffenol can be considered to be perfectly non-toxic.

http://www.flickr.com/groups/caffinol_private_palace/
 
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