Development times for rotary processor

Hi

I have a rotary processor (CPE2) which I have started to use for film development. I have been using ID11 stock and reducing times by 15% as per the Ilford instructions and have got perfectly acceptable results.

My question relates to the development with more dilute solutions or more film with the same volume of solution. At present I am using more active developer than is required to process the surface area of the film so it is wasteful.

For argument's sake, if I were to dilute the developer so there was only just enough active chemistry to develop the surface area of film in the tank would the time still be 15% less than that recommended by Ilford for that dilution? In other words when you near the edge of developer activity - i.e. it is near exhausted - does the time need to be extended?

I hope that makes sense. Any advice gratefully received. I am planning on using other developers besides ID11, but would the same principles apply?

I have been using a CPE2 (with lift) for 20 years to develop B&W film.

I have nearly always used D76 1+1 which is pretty close to ID11 as far as I know. I never pre-wet and I find that the suggested times for normal developing from Ilford with their films and developers are very close for a starting set of times.

If you are already having good negatives then I would feel you should possibly stay with what works. Remember that you are using close to half the amount of chemicals compared to inversion developing, before you start to dilute further.

If you really get into a fair amount of developing think about mixing up chemicals from scratch, it's wonderful, easy and extremely cheap. With the benefit of always having fresh developer inside 10 or so minutes from walking into the darkroom.

Mick.

Hi !
Well it is difficult to say :
I don't know if Ilford publishes minimum volume requirement for ID11 stock solution.
If the developer was Xtol, Kodak recommend not less than 100 cc stock per 135/36 or equivalent surface. At 1+1 it is 200 cc chemistry, enough for some 1500 series tank.
But if it was Rodinal, you need at least 6 cc concentrate as per Agfa instruction...
It is difficult to reduce the amount of perishable chemistry in a rotating tank because the movement increase the oxidation rate a lot. (look at PMK rotary processing instructions) So I, for one, won't reduce the total amount of active chemistry in a Jobo tank without doing tests with "scrap film"....

I use a Jobo ATL-1500; using a 5-minute prewet (recommended by Jobo for this machine; never any problems with uneven development) I find that a 10-15% reduction in standard small-tank development times is about right for my purposes with nearly every developer I've tried, including ID-11/D-76 1+1. Not sure how this machine's automatic agitation speed compares with that of your Jobo, however.

Kodak's tech publication for D-76 does not explicitly state the minimum solution volume required per roll. It does state that, diluted 1+1, ~500 mL will process one 35mm roll equivalent (1x 120, 1x 8x10 sheet) and ~1000 mL will process two of those, without having to increase development time. You can do it in about half that diluted volume by increasing development time 15% I think it is.

This would seem to imply that about 200-250 mL of stock solution is required per roll; since ID-11 / D-76 is cheaper than sand, and since we are all looking for consistent and reproducible results, I think this is a good rule of thumb and is one I've followed. (For Xtol, Kodak recommends at least 100 mL of stock per roll, regardless how it's diluted.)

I second the recommendation to mix it yourself. I've used D-76H of late; it omits the hydroquinone and increases the metol slightly, supposedly conferring greater stability in storage without the pH changes, and activity increase, that can otherwise occur.

mrtoml said:

... if I were to dilute the developer so there was only just enough active chemistry to develop the surface area of film in the tank would the time still be 15% less than that recommended by Ilford for that dilution?

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In general, for continuous agitation, development time increases as the square root of dilution. For example, if you have worked out an "N" time for a stock developer of say 5 minutes, and you add water to double the volume (a 1:1 dilution), your "N" time for the new dilution would be around 5 (sqrt(2)) = 7 minutes.

Note that this has nothing to do with that 15% number you are using from Ilford. That number is an attempt to adjust times from another method (small tank?) to continuous agitation (Jobo) for the same developer and same concentration. It's just meant to give you a starting point for doing your own normal development time testing.

Mick Fagan said:

I have been using a CPE2 (with lift) for 20 years to develop B&W film.

I have nearly always used D76 1+1 which is pretty close to ID11 as far as I know. I never pre-wet and I find that the suggested times for normal developing from Ilford with their films and developers are very close for a starting set of times.

If you are already having good negatives then I would feel you should possibly stay with what works. Remember that you are using close to half the amount of chemicals compared to inversion developing, before you start to dilute further.
Mick.

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Dear Mick,

Come on! You know you could be barred for this! Sensible advice, based on experience? No-one will ever listen!

Cheers,

R.

Better to waste a tiny bit of chemistry than to waste a valued sheet or roll!!..Evan Clarke

eclarke said:

Better to waste a tiny bit of chemistry than to waste a valued sheet or roll!!..Evan Clarke

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I tend to agree. I was just curious as to people's experiences with this. For example, I am developing 4x5 sheet film in a 2521 tank so if I have to develop 4 sheets (which is fairly common for me) I use 300ml stock ID11 which is actually enough for 6 sheets at least in theory. I agree that ID11 is pretty cheap, but other developers like DD-X which I am also trying are not so cheap.

I guess I am also confused about the figures given in the instructions which state that 1 litre of stock is enough for 10 35mm films (which I assume is 20 sheets). But then there are figures for reusing the developer with extended times so presumably you could develop much more than 20 sheets with 1 litre if you figured out the times correctly, but maybe it is not worth it.

Thanks everyone for your considered replies.

Mark.

Mark, part of the trouble is that different developers require different stock-volume minimums--assuming the information exists at all. It's 100 mL for Xtol and higher for D-76, and quite a bit lower for HC-110 syrup. Guess it makes sense, reflecting the differing "energies" of various developers.

Also, I've always heard it stated that a "roll" means one 120 roll or one 35mm/36 exp roll or one 8x10 sheet or four 4x5 sheets. That would mean that the liter of stock needed for ten 35mm films would in theory suffice for forty 4x5 sheets--though I'd not cut it that close.

For instance, I've never precisely measured the maximum solution capacity of my ATL-1500's chem bottles, but it's probably about 700 mL. This means that, with--for example--Xtol at 1+1, I have room for 350 mL of stock, so enough for 3-4 rolls or 12-16 4x5 sheets (haven't done any 4x5 in a long while, hope to change that soon!).

Or, with Kodak's vague D-76 guidelines in mind (200 mL stock/roll), I have barely enough capacity to do two rolls at a time at 1+1. Turns out that it's been a long time since I've done more than two at a time, so I can't recall whether this limitation really applies in practice.

I can get up to SIX rolls in a large Jobo tank by doubling up 120 rolls on the reels, but this would mean straight Xtol, and would seem to rule out D-76 at all. Or I could cram in twelve 4x5 sheets, which should still allow me to use 1+1 Xtol or straight D-76 within the capacity limitations of the Jobo's chem bottles.

Whew. Enough cipherin' for one day. It's cool and crisp outside, so it's film-burnin' time.

MikeSeb said:

Or, with Kodak's vague D-76 guidelines in mind (200 mL stock/roll), I have barely enough capacity to do two rolls at a time at 1+1. Turns out that it's been a long time since I've done more than two at a time, so I can't recall whether this limitation really applies in practice.

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This is what I read in the Kodak guidlines about D-76.

"The development times in the following tables are starting-point recommendation; for critical applications, run tests to determine the best development time. If your films are consistently too low in contrast, increase the development time slightly (10 to 15 percent); if they are too contrasty, decrease the development time slightly (10 to 15 percent).

If you use D-76 Developer diluted 1:1, dilute it just before you use it, and discard it after processing the batch of film. Before using the diluted developer, make certain that there are no air bubbles in the solution. If air is coming out of the solution and forming bubbles, let the solution stand until the bubbles dissipate. Don't reuse or replenish the diluted solution. You can develop one 135-3 roll (80 square inches) in 473 mL (16 ounces) or two rolls together in 946 mL (one quart) of diluted developer. If you process one 135-36 roll in a 237 mL (8-ounce) tank or two 135-36 rolls in a 473 mL (16-ounce) tank, increase the development time by 10 percent"

In this case a minimum of 120 mL stock solution would be enough for one rol of 135 or equivalent. But you must increase the dev time. Is that right?

MikeSeb said:

Also, I've always heard it stated that a "roll" means one 120 roll or one 35mm/36 exp roll or one 8x10 sheet or four 4x5 sheets. That would mean that the liter of stock needed for ten 35mm films would in theory suffice for forty 4x5 sheets--though I'd not cut it that close.

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Thanks Mike. It was my mistake (confusing 2 sheets per 35mm roll while it is obviously 4). Shouldn't post to these forums before I have my quart of coffee in the morning...

I have found some other information on Jobos website (for Xtol) and Kodak's website about processing in Jobos, but it is slightly contradictory. And in the case of Kodak they only cover D76 in detail with Kodak films (whereas their Xtol document covers other brands of film).

Looks increasingly like erring on the side of caution with the chemistry is the only way to proceed.

mrtoml said:

Shouldn't post to these forums before I have my quart of coffee in the morning...

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Yeah, the I.V. gets in my way when I'm trying to type...

mrtoml said:

Looks increasingly like erring on the side of caution with the chemistry is the only way to proceed.

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That's about it. I'm gonna allow about 100 mL of Xtol stock, or 200 mL of D-76 stock, per "roll". Even if I weren't using a Jobo, I'd be single-shotting developer; it's just penny wise / dollar foolish to exert oneself shooting the film , only to risk it on skanky used developer.

I've been mixing my own D-76H, and for me that's the way to go. (This formulation has a bit more metol and omits the hydroquinone, supposedly solving the commercial mix's problem of instability and increasing activity over the first month or so of storage. Seems to work identically with the OTC stuff.) Always fresh (mixed 1 L at a time), solves my problem of increasingly long intervals between rolls of film and having developer go south on the shelf. And CHEAP.