[pure-silver] Re: Developing Plus-X in Rodinal 1+100
----- Original Message ----- From: "Martin Jangowski" <martin@xxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, December 16, 2008 4:21 AM
Subject: [pure-silver] Re: Developing Plus-X in Rodinal 1+100 



On Tue, 16 Dec 2008, Horvath Krisztian wrote:


Hello All,
Can the "constant agitation" be the keywords? I can imagine that a periodic "some" inversions in 30sec-1min-2min-etc. is far enough from constant agitation, so Rodinal die later. A friend of mine made an experiment with a third of a roll of T-Max in Rodinal 1+250 (2ml Rodinal in 500ml water), 90min at 24 °C (75 deg F.) Agitation was once in every min for the first ten minutes, then 30sec in every 5 mins. The result was OK, so it seems to me that if the agitation is not continuous, Rodinal doesn't die so soon.
The real question is: is there a difference between eg. 20min of thin rodinal and 40min? Should the rodinal die after 17min there should be no difference... after all, sloshing the film around for a few more minutes 
in dead rodinal won't change anything.
Personally, I don't care... I spent a few weekends with games like this and found no visible differences in the results, so I use faster 
development.


Grüße aus Hohenlohe,

 Martin Jangowski
I am curious about this research, what exactly what being tested? The development potential is an old method of testing for the activity of developers but I am not at all sure its considered valid any more nor do I think this is what was being tested for here. Developers do not "wear out" or get "used up" in the way we conventionally think. For the most part the loss of developer activity with use comes more from the accumulation of reaction products and restrainers (mostly bromide and iodide ions from the film). It would be easy enough to test the activity of used, diluted, Rodinal, simply duplicate the conditions under which the developer is supposed to become useless and then try it with some fresh film to see if any development happens. There is certainly not much very much developing agent, or anything else for that matter in Rodinal diluted 1:100 but that is not the same as saying that its "dead". I haven't the means to conduct this simple test at the moment but I am sure there are others on the list with the wherewithall and necessary curiousity to do so. Rodinal is paraminophenol in a highly alkaline solution. Paraminophenol is related to Metol and like it has reaction products which are restrainers of development so its possible that in a diluted solution enough reaction products may accumulate to slow development beyond a practical limit, but one must test. Having said all this I must repeat that, IMO, Rodinal is not the optimum developer for any film. Its main virtue is that its highly convenient and gives good results with nearly anything but other developers will yield higher speed or finer grain or both although Rodinal at normal dilutions usually will give good tone rendition. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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