I know this question has been asked and answered before but I can't seem to find the answer.

What's the minimum amount of Rodinal necessary for roll film development? I'm diluting 1:75 and 1:100 for 120 film. My tank holds 500ml so that would leave me with either 7.5ml or 5ml of the juice. Is that enough? Should I use a larger tank?

thanks

david

-- David Parmet (david@parmet.net), August 02, 2001

Answers

The Agfa recommendation is 18 films per 125ml of Rodinal concentrate, which works out at just under 7ml per film. I presume they mean 36 exposure 35mm, which has the equivalent area to about one and a third rolls of 120.
So, just over 5ml per 120 film is within Agfa's spec.
I admit I've personally never used Rodinal with 120 film at those high dilutions, though.

-- Pete Andrews (p.l.andrews@bham.ac.uk), August 02, 2001.

I have used Rodinal at 1:100 and 1:75 in 500ml tanks for 120 film with no apparent problems. I usually only use such high dilutions for slow films.

-- Ed Buffaloe (edb@unblinkingeye.com), August 02, 2001.

What happens if you have slightly insufficient developer? I suppose development proceeds normally until exhaustion approaches, then what? I recently tried to ascertain whether 250mL of normal PMK was really adequate for a 36exp 35mm film, and I could not tell the difference between it and using 500mL. I judged this by some zone_1 frames at a range of speeds. Exactly the same, as far as a "proper proof" was concerned. I have no access to a densitometer. I did not test for heavily exposed frames. If those were the only ones affected, maybe it would be useful rather than a problem to allow exhaustion.

-- john stockdale (jjss@bigpond.net.au), August 02, 2001.

Hi John. "What happens if you have slightly insufficient developer?"
The maximum density is curtailed, and it's called compensating development.

-- Pete Andrews (p.l.andrews@bham.ac.uk), August 03, 2001.

Insufficient developer quantity is not called compensation, it is called exhaustion--thus, failure. More importantly, if developer is used to exhaustion, there is no way to ensure consistent, repeatable results.

As for using 250ml of PMK for one 35mm roll, Gordon Hutchings claims in his book that this quantity is sufficient.

-- Ted Kaufman (writercrmp@aol.com), August 03, 2001.

Actually, every compensating development technique I know relies on controlled exhaustion as the mechanism. That is, you want the developer to exhaust in the highlights but keep working in the shadows. Its also a good idea to distinguish between using a developer that is 'in a state of exhaustion' from using a developer 'to exhaustion'. The former typically refers to using a developer one-shot but the developer is compounded to be in a state of exhaustion (a good example is POTA - it is in a state of exhaustion from the moment it is compounded). The latter refers typically to reusing a developer till it reaches exhaustion. The latter is problematic for ensuring consistency because the composition of the developer changes in addition to its getting exhausted (repeated development adds bromide to the solution etc which is likely to affect speed in addition to the maximum density obtainable etc). OK, that's my pedantry fix for this morning. Cheers, DJ.

-- N Dhananjay (ndhanu@umich.edu), August 03, 2001.

This is what I received from the fine folks at Agfa when I asked this a bit ago.

Subject: Response to Minimum amount of Rodinal needed per 8x10 film unit?

Dear Dan,

in our technical data we mention that 500 ml concentrate of RODINAL will last for 50 films (135-36). That means that you need 10 ml concentrate to process 1 film. It does not matter what the dilution is. Important is that you are using 10 ml concentrate. For example if you are processing with a dilution of 1+50 than you need 10 ml concentrate plus 500 ml water so that you will have in total 550 ml solution to process your film. Why is it importatn to take 10 ml because these 10 ml contain the amount of substances which will be used to process your film correctly and with reproducible results. It can be that you will get good results with less than 10 ml as mentioned in one answer but to be sure we recommend 10 ml. I hope this will answer your question. If you have further questions please do not hesitate to contact me.

Kind regards Wolfgang Holz Product Manager Marketing Chemicals

Agfa-Gevaert AG

-- Dan Smith (shooter@brigham.net), August 03, 2001.

Ted: I know GH says 250mL is enough. I shouldn't have doubted him! I was just responding to the suggestion in Anchell + Troop where they suggested 500mL for developers in a category of developers at a certain dilution rate.

Compensation: developer exhaustion (due to inadequate quantity) may well be different to a dilute developer becoming exhausted in the emulsion. I'm not sure what to expect.

Consistency + Repeatability: Good point. Strength of my favourite developer (PMK) may well be a bit variable with age, chemical purity etc.

-- john stockdale (jjss@bigpond.net.au), August 03, 2001.

Im rather confused about this post :-

Dan posted it from Agfa, " in our technical data we mention that 500 ml concentrate of RODINAL will last for 50 films (135-36). That means that you need 10 ml concentrate to process 1 film. It does not matter what the dilution is. Important is that you are using 10 ml concentrate. For example if you are processing with a dilution of 1+50 than you need 10 ml concentrate plus 500 ml water so that you will have in total 550 ml solution to process your film. Why is it importatn to take 10 ml because these 10 ml contain the amount of substances which will be used to process your film correctly and with reproducible results. It can be that you will get good results with less than 10 ml as mentioned in one answer but to be sure we recommend 10 ml. I hope this will answer your question. If you have further questions please do not hesitate to contact me.

Kind regards Wolfgang Holz Product Manager Marketing Chemicals

Agfa-Gevaert AG "

Wolfgang Said, "For example if you are processing with a dilution of 1+50 than you need 10 ml concentrate plus 500 ml water so that you will have in total 550 ml solution to process your film."

Surely that should be 500ml of water and 10ml of solution making 510ml not 550ml ? -Mike.

-- Mike (picnet@co.inet.fi), August 25, 2001.