Temperature-correction of *Paper* development-time

Most of us are aware that development-time of negatives should be adjusted based on temperature. And Ilford has a table of such times which are based on the assumption that time must be decreased by 8.8% per degree-C of temperature-rise.
The correction is 8.8% per degree for Ilford's *film*.

Does anyone know what correction should be used for *paper*?

As some have pointed out, development of paper does *not* have a completion. Rather, after the most-exposed areas reach Dmax, the lighter areas continue to darken. In my recent experiment, this darkening was obvious both visually and in my densitometer measurements when I developed for 1.5 minutes compared with 1 minute. Therefore, to get consistent midtones and highlights, development must be consistent. And that means being careful about temperature. Hence my desire to know how to correct for temperature of paper developer.

Mark Overton

I have Zone VI compensating timer. I rarely need it as I keep a little heater going when it's chilly. I develop for 2 minutes with Bromophen 68- 70 degrees. I make up fresh developer from stock solution for each session. I have a microwave in my darkroom if chemistry needs a very few seconds to warmup.

albada said:

when I developed for 1.5 minutes compared with 1 minute

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Did you do the tests with new Ilford MG RC V paper? I've found that same effect. Very small difference, but it is there.

BTW: Do a 1 minute / 2 minute / 8 minute tests too, I think 1/1.5 is a bit short distance.

I would approach the problem by employing factorial development.
https://www.photrio.com/forum/threads/determining-factor-for-factorial-development.138627/

ighter areas continue to darken. In my recent experiment, this darkening was obvious both visually and in my densitometer measurements when I developed for 1.5 minutes compared with 1 minute

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My non-expired Ilford fiber paper retains white after quite a while in room temp Dektol. I only see that kind of fog with expired paper or when I had a bad safelight.

Development can be timed to ensure completion if one has an appropriate dim safelight or the prints are processed image down (making factorial development difficult). Temp can be brought in to the equation to shorten times if one is in a hurry, but what I do is develop to completion by time based on the coldest and oldest Dektol I usually use. For me that is 2 min for Ilford MG FB cold tone, 2:1 Dektol one-day old. So, all prints get 2 min.

I had thought that Mark is looking for a table that tells him what change he needs to make to get the same print, say at 20C when his developer temp may have changed slightly from what it was at,say, the start of a session when he got the development he needed and was happy with?

Do the references to factorial development and the posts so far address that issue? Assuming of course that I have understood what it is that he seeks

pentaxuser

pentaxuser said:

I had thought that Mark is looking for a table that tells him what change he needs to make to get the same print, say at 20C when his developer temp may have changed slightly from what it was at,say, the start of a session when he got the development he needed and was happy with?

Do the references to factorial development and the posts so far address that issue? Assuming of course that I have understood what it is that he seeks

pentaxuser

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You aren't likely to find such a table, because people tend to use print developer until it is near exhausted, not until its behavior changes due to use.
It is normal to deal with the normal change of print developer activity during a printing session by lengthening their "standard" developing time. It is practical to do that because we can observe the activity under safelight.
Factorial development takes into account both temperature and slowly reducing (because of use) developer activity.
It might very well be useful to keep track of how temperature seems to affect developer activity when developer is fresh. That would make it a bit more convenient to start a printing session.

Mark,

I approach the issue from a different angle. Extending development time with paper results in the same curve shift and adding print exposure. When making a print, I standardize on a development time that's a bit longer than recommended, usually 2.5 minutes in ID-62 or D-72. Then, as I'm refining my print, I can add or subtract a little development time to refine my print exposure instead of having to make impractically small changes in actual print exposure. 15 seconds more (or less) development often makes a visible difference. Sometimes I'll make two or three identical prints with different development times and see which one I like best. I vary print development times between two and four minutes usually. Longer than that and I'll make a change in print exposure time.

Of course, this approach is based on making a fine print in one session and not having exact repeatability at a later date. However, setting up in a week or a month or a year later to make a copy of a print that I made earlier usually entails some changes in the original print interpretation, not to mention exposure, manipulation and development scheme anyway; the records I so meticulously keep are just starting points to get me in the ball park.

The only reason for exact temperature control is repeatability if you plan on making the exact same print later on the first try, or if you're controlling variables for testing purposes. In this latter case, you'd be better off coming up with some kind of temperature control.

If you really need some factor, then using the 8.8% factor for film should get you really close. It's based on the increase in chemical activity in relation to temperature, not the characteristics of any specific emulsion (different films have significantly different emulsions too).

Factorial development is another approach, but I've found it way to imprecise as concerns repeatability. Some use it to compensate for loss of development activity as the developer slowly exhausts, but I find that use imprecise as well. I make a fine print with the developer I have in the state that it's in (trying, of course, not to use the developer close to exhaustion). Tweaking print exposure and development time on the spot for each run of prints seems the most practical approach for me given that I don't have precise temperature control (although I do use a compensating timer and keep the ambient temperature between 67° and 74°F) and the fact that the developer changes activity somewhat with use during a session.

Best,

Doremus

Like mshchem, I've used a Zone VI Compensating timer for probably around 40 years. Coincidentally, though, John Finch of Pictorial Planet just posed a short YouTube video on factorial development. You may wish to watch this, if interested.

Alan9940 said:

Like mshchem, I've used a Zone VI Compensating timer for probably around 40 years. Coincidentally, though, John Finch of Pictorial Planet just posed a short YouTube video on factorial development. You may wish to watch this, if interested.

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Just one day old, and that video has already has hundreds of views. That bodes well for the market for film-photography. Thanks for mentioning this video. In it, John suggests using paper-developer until its emergence-time of mid-grays has increased 50% from when it was fresh. My Liquidol emergence-time is 20-22 seconds when fresh; I'll have to keep an eye on it.

The video suggests using a factor of 5. Others suggest 6. 22 seconds times 5 is 110 seconds; almost two minutes. But the instructions for Liquidol (and my experience with it) say that one minute is fine. That would be a factor of only 3. The big difference between 3 and 5 or 6 makes me question factorial development.

The Zone VI Compensating timer has a film-paper switch, which I presume selects different correction-rates for temperature. That feature of the Zone VI Compensating timer is the reason I started this thread. I was wondering what the correction-rate for paper is.

pentaxuser is correct: I am trying to develop very consistently because I am creating H-D curves. These will go into the LED controller for my enlarger, so I want them to be accurate. In more detail, I am programming knowledge of zones into the controller so the controller will know the exposure-change between any zone and zone-9. In effect, that is an H-D curve. I have 8 such curves to cover the range of contrasts. And these 8 curves must be created for each type of paper. My first two are Ilford MGRC Deluxe ("MGRC V" as it's often called), and Foma RC. Ilford MGFB will follow. Then I'll quit out of exhaustion.

I started a new thread describing my accurate-but-half-DIY reflection-densitometer: https://www.photrio.com/forum/threads/accurate-reflection-densitometer-for-120-with-diy-part.189738/ I'm proud of this thing. It's serving me well for this H-D curve work.

Mark Overton

albada said:

My Liquidol emergence-time is 20-22 seconds when fresh; I'll have to keep an eye on it.

The video suggests using a factor of 5. Others suggest 6. 22 seconds times 5 is 110 seconds; almost two minutes. But the instructions for Liquidol (and my experience with it) say that one minute is fine. That would be a factor of only 3. The big difference between 3 and 5 or 6 makes me question factorial development.

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What I take from your posts is that you are seeking consistency more than anything else.
If your emergence time is 22 seconds, one minute is a fairly short total development time. I would not be surprised if the one minute recommendation in the Liquidol instructions was formulated in relation to older versions of the Ilford papers.
My personal preference is to use longer development times. With that in mind, I find that factorial development with a factor of 5 works well, in that it gives me good consistency, session to session.
There is of course a possibility that the tone I'm looking for is different than the one you are. That difference though should be counteracted by a personalization of the "factor" in use.

Maybe your safelight is fogging the paper. I have developed fiber-based Ilford MG for 1.5x the recommended time and the whites never suffer.

albada said:

Just one day old, and that video has already has hundreds of views. That bodes well for the market for film-photography. Thanks for mentioning this video. In it, John suggests using paper-developer until its emergence-time of mid-grays has increased 50% from when it was fresh. My Liquidol emergence-time is 20-22 seconds when fresh; I'll have to keep an eye on it.

The video suggests using a factor of 5. Others suggest 6. 22 seconds times 5 is 110 seconds; almost two minutes. But the instructions for Liquidol (and my experience with it) say that one minute is fine. That would be a factor of only 3. The big difference between 3 and 5 or 6 makes me question factorial development.

The Zone VI Compensating timer has a film-paper switch, which I presume selects different correction-rates for temperature. That feature of the Zone VI Compensating timer is the reason I started this thread. I was wondering what the correction-rate for paper is.

pentaxuser is correct: I am trying to develop very consistently because I am creating H-D curves. These will go into the LED controller for my enlarger, so I want them to be accurate. In more detail, I am programming knowledge of zones into the controller so the controller will know the exposure-change between any zone and zone-9. In effect, that is an H-D curve. I have 8 such curves to cover the range of contrasts. And these 8 curves must be created for each type of paper. My first two are Ilford MGRC Deluxe ("MGRC V" as it's often called), and Foma RC. Ilford MGFB will follow. Then I'll quit out of exhaustion.

I started a new thread describing my accurate-but-half-DIY reflection-densitometer: https://www.photrio.com/forum/threads/accurate-reflection-densitometer-for-120-with-diy-part.189738/ I'm proud of this thing. It's serving me well for this H-D curve work.

Mark Overton

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Personally, I think you are worrying about nothing. If you want to do calibration work just mix up a decent quantity of developer. You will probably be doing small prints for the calibration so developer exhaustion shouldn't be an issue unless you have ultra long print sessions where the developer oxidises or you run dozens and dozens of sheets through the developer. You might dilute Dektol 1:1 instead of the usual 1:2.

Factorial development is only of any use when you are printing many prints from the same neg and want to keep the print densities consistent as the developer deteriorates.If you are just making one or two prints from the same negative it would be silly to even think about factorial development. My personal thoughts on factorial development is that if you can see the emergence of some particular dark tone consistently your safelights are probably too bright. I can barely see anything until the print is almost fully developed but I have. DARK darkroom. No safelight fog in my darkroom.

Pieter12 said:

Maybe your safelight is fogging the paper. I have developed fiber-based Ilford MG for 1.5x the recommended time and the whites never suffer.

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I didn't make myself clear. My whites are not suffering. What I meant was that the tones (below Dmax) get darker with increased dev-time. But my whites and blacks are identical for both one-minute and two-minute times. It's the in-between tones that darken with additional dev-time.

markbau mentioned that his darkroom is very dark. Mine is rather dark too, so it's hard to see tones in the developer, because mid-gray and darker look black to me. I cannot judge "completion" of development, so I rely solely on time. I also cannot read the f-stops on the lens, nor can I read normal handwriting in that darkness. I must write my planned exposure-info with a felt-tip pen (Sharpie) in big letters.

markbau: I thought one purpose of factorial development was to avoid discarding used developer. In the Pictorial Planet video cited above, John Finch says that he waits until mid-gray emergence-time has increased 50% wrt fresh before discarding developer, and he uses factorial development (factor=5) to compensate for partial exhaustion of developer.

Mark Overton

MattKing said:

What I take from your posts is that you are seeking consistency more than anything else.
If your emergence time is 22 seconds, one minute is a fairly short total development time. I would not be surprised if the one minute recommendation in the Liquidol instructions was formulated in relation to older versions of the Ilford papers.
My personal preference is to use longer development times. With that in mind, I find that factorial development with a factor of 5 works well, in that it gives me good consistency, session to session.

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You are correct: I'm 99% sure that Liquidol was introduced before Ilford introduced its new MGRC V paper, so that paper could need more time. Thanks for pointing this out. I will probably switch to 100 seconds (about 5x) in response to your posting.

Mark Overton

albada said:

You are correct: I'm 99% sure that Liquidol was introduced before Ilford introduced its new MGRC V paper, so that paper could need more time. Thanks for pointing this out. I will probably switch to 100 seconds (about 5x) in response to your posting.

Mark Overton

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I know this is slightly off topic but I've often wondered, if a RC paper does not have a developer incorporated emulsion, how is full development achieved in one minute compared to a FB paper which takes 2 minutes?

I've used a tray warmer for decades, so my developer is a constant temperature throughout the year. The effects of temperature change or development time are far more consequential with warm tone papers, where an increase in development decreases the warmth, having a significant effect on the colour of the tones. So we have a control of colour by decreasing or increasing development with a corresponding change in exposure, however that's not the case with Bromide papers including MG V.

markbau said:

I know this is slightly off topic but I've often wondered, if a RC paper does not have a developer incorporated emulsion, how is full development achieved in one minute compared to a FB paper which takes 2 minutes?

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While RC papers are no longer developer incorporated, there are adjuncts added to speed up development and surfactants are added to aid in coating which also help with move even processing. The original RC Ilfospeed was developer incorporated and I ran it though an lIfoprint machine using homemade Activator (no developing agents) and fixer instead of stabiliser.

Ian

Alan9940 said:

Like mshchem, I've used a Zone VI Compensating timer for probably around 40 years. Coincidentally, though, John Finch of Pictorial Planet just posed a short YouTube video on factorial development. You may wish to watch this, if interested.

Click to expand...

Just watched the video. He's saying that to increase contrast, increase the factor. Extended development just produces a darker print, it doesn't increase contrast unless you're a newbie who thinks that darker prints have more contrast. But don't believe me, read Henry's "Controls in Black & White Photography" Why do people complicate the darkroom process?

markbau said:

I know this is slightly off topic but I've often wondered, if a RC paper does not have a developer incorporated emulsion, how is full development achieved in one minute compared to a FB paper which takes 2 minutes?

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In addition to Ian's observation, I expect that fire based paper's tendency to absorb developer plays a role in changing development time.
I visualize the emulsion on fibre based paper being surrounded by developer, with the developer behind it becoming more and more exhausted and laden with development byproducts.

You know the Zone VI paper temperature curve has been published. It’s either in a Zone VI newsletter or maybe in Curt Palm’s reverse engineered CompnTemp help documents…

Check out the manual from Curtpalm.com - everything you need is there..

http://curtpalm.com/CompnTemp.pdf

Kodak never ever provided any time-temperature compensation for processing paper...it merely suggested processing at 68F, with the range of 65-75F, and times for a number of different brands/models of printing paper. Specific developer+paper combinations had times all falling within the range of 45-120 seconds, many 60, 40% of them 60, 40% of them 120, the rest 90sec.

this statement based on review of Kodak Master Darkroom dataguide from mid-1960's and one from 1988.

This is somehow a very lazy question, might be even bordering on a joke.

Two prints are never the same.

A print is submitted to no standard except by the printing session at which it is happening.

Your test strip, or test print, will define the final
Print. There is no “standard”. If your satisfying test strip was developed fir 1:15, then you stick 1:15 for the final print, regardless of the development time you used last time.

markbau said:

Just watched the video. He's saying that to increase contrast, increase the factor. Extended development just produces a darker print, it doesn't increase contrast unless you're a newbie who thinks that darker prints have more contrast. But don't believe me, read Henry's "Controls in Black & White Photography" Why do people complicate the darkroom process?

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Never said that I agreed with anything in that video. I was simply pointing to a very recent reference regarding factorial development. Draw your own conclusions.

If you take William Mortensen’s advice you’d develop prints for fifteen minutes.

I tried it on a print with difficult to tame highlights and it seemed to make a helpful difference.

More tests of course, are required to prove whether same result could have been arrived at with a longer exposure.

Knowing the factorial or the time/temperature parameters will help for edition prints, to keep prints that should look the same... looking the same as each other.