Why the ultra disolved developer?

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Why does everyon keep talking about such large (i.e. 100:1) developer dilutions, How can anything be developed with such little developer? Why can't we just use the manfucturers suggestion and less volume? Also isn't significantly more time necessary to develop at these decreased potencies? Are these figures just for the special minox tank or can they be used with other methods as well? Thanks!

-- Catherine Coz (cc473@is9.nyu.edu), May 02, 1999


Cathy, highly dilution is a technique to handle microfilm, which has extremely high contrast, for example Kodak Technical Pan film and Agfa Copex Rapid etc. If one use normal dilution, the resulting contrast will be too high and not printable.

High dilution slows down the developing process, and makes it controllable, in other words highly diluted developer tames high contrast film.

For ordinary B&W film such as Agfapan APX 25, 100, 400, it is not necessary to use high dilution developer, 1:1 to 1:15 is good enough. Unless you are into ultrafine grain microfilm, don't worry about 1:100. It is indeed possible to develop Kodak Technical Pan with very little chemical .

There is a limit to the degree of dilution. Too high a dilution for example 1:200 or 1:300 only increase the development time and does not provide any added advantage.

-- martin tai (martin.tai@capcanada.com), May 02, 1999.

Highly diluted developer has a property which makes it a favourite of subminiature photographers: accutance due to the "edge effect". The border of an image ( a line for example ) is in contact with fresh developer, hence developed more than the inner part of image, where developer is more likely to be exhausted and developed less, the result is an image detail which has sharp edges and has higher accutance.

-- martin tai (martin.tai@capcanada.com), May 03, 1999.

I never have used one of the high dilution developers (say Rodinal 1:100) with a film such as Technical Pan but I have used Technidol Liquid with Tech Pan and have been quite pleased with the results although I thought the negative was contrasty it did print well. How do the two developers compare? A real disadvantage to the Technidol is its shelf life once mixed--7 days. With one envelope being enough for 1 35mm roll of film that would work out to about 416 minox exposures (the center half of two 35mm rolls which yield 4 rolls of 40 exposure and two of 24 each). I would expect Rodinal at least to be much more economical.

-- Ken Trettin (hogman@netins.net), May 04, 1999.

Many Technical Pan photographers after tried out 1:100 Rodinal switch from Technidol to Rodinol. It is worth a try.

Rodinal concentrate has long shelf life. It takes only about 1cc of Rodinal to develop a roll of Minox film. I like to use the fine grain version of Rodinal, called "Rodinal Special", it is a formular containing Para-aminophenol ( Rodinol) and Hydroquinone and probably sodium suphite. Very simple to use, take one cc of Rodinal Special mix it with 80 cc distilled water, develop tech pan in 20 degree C in Minox tank, 16 minutes

But Rodinal- Special is only available in Canada and Europe, not sold in USA. If you try 1:100 Rodinal, don't use pure Rodinal; instead mix the developer with distilled water with sodium sulphite added (56 g sodium sulphite in 1 litre water )

-- martin tai (martin.tai@capcanada.com), May 05, 1999.

I just developed a roll of 35mm Tech Pan with Rodinal at 100:1 mixed with water and sodium sulfite added at 56g per liter for 6 minutes at 68F and it turned out really well. I am now going to develop a roll of Tech Pan in my Minox developing tank using the same formula. I note that you suggest a time of 16 minutes for Rodinal Special. What time do you think I should use. The difference between 6 minutes and 16 minutes seems very high.

-- Charlie Mallia (cmallia@ibm.net), May 07, 1999.

I use Rodinal-Special 1:80 dilution, 20 degree C 16 minutes.
  1. Rodinal Special is a fine grain developer, Rodinal is not. Fine grain developer is usually milder and slower
  2. Sodium sulphite is an akaline component; the more alkali the stronger the developer, it acts like an accelerator, it shortens the development time. Kodak DK 50 developer uses only 30 g of sodium sulphite per 1000 cc water, the alkali in your develper is almost twice that of DK50, hence the development time is very fast, but it is not a fine grain developer.
  3. If you use Minox tank, I think 6 minuites may be sufficient for 1:100 Rodinal + sulphite, if you recycle/replenish the developer. I suggest you start with 1 cc Rodinal in 100 cc of distilled water (with sodium sulphite) pour 50 cc in to the tank at every minute interval add 10cc into the center, let the developer overflows from the snout; by the end of 6 minutes, you have used up all the 100 cc and complete the development.

    -- martin tai (martin.tai@capcanada.com), May 07, 1999.

I just used the method suggested by you in my Minox tank. Rodinal 1:100, 6min, 68 degrees F, replenish/replace 10ml each min. and I want you to know that my negatives came out very very good. I would like to try Rodinal Special sometime. It will have to wait untill my next trip to Toronto as it is not available in Nova Scotia. Thanks for the advice. Charlie

-- Charlie Mallia (cmallia@ibm.net), May 09, 1999.

Another alternative for Tech Pan: Microphen developer, diluted 1+5, 14 min. @ 75 deg. F, EI 32.

-- Tim Brown (brownt@ase.com), May 12, 1999.

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