Low optimum temperatur for Rodinal?

[A49]

Hello friends of self-developing b/w,

I recently read again in an old German book by J. M. Eder "Rezepte, Tabellen..." (from 1949) that Rodinal (the original formula) develops "best" at 16 Celsius (60.8 Fahrenheit) in contradiction to the 20 C standard. Unfortunately the book does not say what "best" does exacly mean, if it is the grain, sharpness, speed or tonality or all of them that then become(s) "best".

Has anyone got an opinion or own experiences regarding Rodinal´s temperature and the claimed 16 C optimum? Maybe also some of the many modernized Rodinal´s descendants have got a low optimum temperature...

Best regards,
Andreas

[ic-racer]

If the time at 20C is less than 5 min, then at 16C it may have better evenness of development.

In the winter (when I can get a good cold water source) I use T-max developer at 16c in the Jobo. I use it for some very contrasty microfilm I process for a full tonal scale. It needs 4 min at 16C

[Stephane]

I use cold (17C) rodinal diluted 1:100, normal time is 12mn with constant agitation. I also overexpose the film by 2 stops. If the scene is too flat, I wont do that. My feeling is that the longer you leave it without blowing highlights, the better it is for the midtones, which will have time to buildup.
So if you want to develop in cold solution, you will have to adjust one or more of the usual parameters (dilution, development time, exposure).

[mikew]

If they were saying that Rodinal's "optimal" developing temperature is lower than 20C I would suspect that it's because - generally speaking - a lower developing temperature would extent the developing time and reduce contrast. I don't think it would have anything to do with grain because Rodinal is a non-solvent developer; if anything, I would think that "optimal" would refer to acutance and tonal separation, particularly in the high values. In fact, Rodinal is renowned for having it's own kind of gradation so I wouldn't be surprised if there's literature that speaks of ways to maximize it.

I might add that there is an apparent difference between the traditional Rodinal and Agfa Rodinal. It's debatable whether's a visual difference but the chemical composition is definitely different. (I can look up the specific differences if you need)

Personally, I use Rodinal with Efke PL25 and Ilford FP4+. I develop at 20C but use a semi stand agitation method (around 18min developing time) to maximize Rodinal's adjacency and compensating effects. The result is a characteristic curve with slightly more density in shadow values and slightly less density in the highlights; this renders a tonal range where high values have distinct separation and print easily. This process takes more time as I only develop one sheet in a tray at a time but I find the result to be worth it.

Everyone has there own way of doing things. If you're ever in doubt just do some testing and then trust your intuition.

Hope that helps!

Mikew

[A49]

Everyone has there own way of doing things. If you're ever in doubt just do some testing and then trust your intuition.

Thank you, Mikew for your interesting thoughts and for telling your own method of getting your desired tonality with Rodinal.

I also found the adjacency effects very strong with Rodinal. They get easily too strong for my taste, if I do not agitate enough. If they are just right, the resulting image looks very nice and sharp.

Back to the temperature question. I was curious and could take the time for a little (unscientific) testing. I developed two films with the same picture and exposure in Rodinal 1+200. The first one at 14 C and the second at 20 C. I tried to match the density of both which was successful to 90 percent. I was a little disappointed with the result: simply no differences in sharpness and in grain. Maybe the temperatur affects the curve a little bit but I can not tell that for sure because of coincidences in my (as said unscientific) testing. I don´t no why they claimed 16 C as Rodinal´s optimum in the old days, but at this point I would think, higher (or even lower) temperatures of the Rodinal will do as well.

Andreas

[A49]

I forget to mention that did the test with a very low speed (12 ASA) and original high contrast ortho film (FO5) that I currently use. For conventional or T-grain films the Rodinal´s temperature might have effects on sharpness or grain.