How important is temperature in developing B&W film?

[ferider]

After digging some in my archive ... this guy did some quantitative measurements for Rodinal:

http://home.arcor.de/piu58/fotoweb/aufsaetze/Rodinal.pdf

In case you don't read German:

"Je Grad Temperaturerniedrigung erhöht sich die Entwicklungszeit um einen Faktor von 1,13. Bei 2 Grad ist der Faktor 1,3 und bei 4 Grad 1,6."

Meaning

(starting at 20 degrees Celsius) "Every degree of temperature reduction increases the development time by factor 1.13. At 2 degrees the factor is 1.3, and at 4 degrees the factor is 1.6."

For example, 10 minutes in Rodinal 1:50 at 20 degrees is equivalent to 13 minutes at 18 degrees. He also comments on the different behavior of the developer when colder, including dark tones, grain, etc.

Roland.

 

[Jaans]

I am very particular about temperature control. I live in a sub-tropical climate, so sometimes you have to pay close attention to maintaining a constant 20C.

I have found the best way to do this, is have a small 500ml plastic bottle of water kept frozen in the freezer. When you want to develop, then if your developer is say 24 C, then simply drop the bottle in the jug for 45 seconds or so. The temperature will quickly drop down to the desired temperature.

After taking out the plastic bottle, wash the outside of it thoroughly, before using again or putting it back in the freezer. It is a simple and effective way for temperature control.

Some others use baths, which are also good. However, I find the above method faster, as the ambient temperature doesn't increase the developer temperature during development.

 

[alfredian]

Ilford has/had a converter-graph thing

Ilford has/had a converter-graph thing

Ilford does, or used to, have graph/gnomon in their technical specs sheets for every developer. You can view it on their website and find just about any film.

It allows you to see the proper time for any temperature within the acceptable range - a straightedge or transparent plastic ruler helps keep your eye on an even keel. Some films have a steeper slope then others, so a small temperature change can matter. I can't remember if their film spec sheets had a similar graph for different developers.

The developer time/temp graphs are small enough to print out, clip and put up on the wall, cabinet door, whatever, where you do your developing.

 

[Argenticien]

I use the Ilford compensation document mentioned above, so if something would take 8:00 minutes at 20 C, but 5:30 at 24 C, then, sure, I would do 5:30 if I'm at 24C. However, if I've added ice to tap water to get to 20, but hit 19.7 or 20.2, I will call it good and not futz around adding further alternating bits of hot water and ice to exactly nail 20 C. Further, I measure just the mixing water. When I add in the liquid concentrate developer, it is at ambient temperature (I don't bother pre-cooling it), so the overall working solution probably ends up not at the temperature I measured. There is so much other noise in the system anyway -- age/strength of concentrate; imprecision in measuring small quantities of same; extra or lost seconds of development when pouring chemistry in/out; making the exposure at f/5.6 or f/8 when the light meter called for f/6.7 but the camera has no half-stops; age and storage conditions of the film; imperfect shutter timings on 75-year-old cameras; etc.). There is a saying somewhere about "measure with a micrometer, mark with chalk, cut with an axe"; trying for perfection in my development temperature given the variability in all those other factors would be a similarly silly opposite, like "measure by pacing; mark with chalk; cut with a laser." Life is too short...

Full disclosure: I'm a hobbyist only. Might try slightly harder if my livelihood depended on the negs.

--Dave

 

[mike rosenlof]

I too work at ambient temperature. In my basement darkroom that varies from 18C to 22C over the course of the year. Generally very stable. I standardize on 20 deg C as a developing temperature and use the Ilford correction tables (in any of their film data sheets, I think) to adjust to the current temperature.

So, absolute temperature is not super important within a range, but developer termp relative to your standard temperature is critical.

 

[Sylvester]

Well... I develop room temperature and never get in trouble.
When it is about important shots I let my bottle in about 20°C water in my sink for about 20mins.
Never seen real changes, but my darkroom is always at 21-23°C...

 

[mackigator]

I've been developing at room temp but temp swings, winter to summer, are over a wider range. Perhaps 17-24 C. Reading this thread has me considering whether I shouldn't take the extra time to level off at a standard temp, instead of my usual adjusting on time.

Usually DDX or TMax dev and either Tri-X or TMax400.

 

[venchka]

...
Some others use baths, which are also good. However, I find the above method faster, as the ambient temperature doesn't increase the developer temperature during development.

My testing proved otherwise with Jobo drums spinning on a motor base. If I were using small tanks and let them sit in the sink with the rest of my liquids, I might be able to maintain something close to 68F. However, my tap water for 6 months of the year exceeds 80F. As a result, I turn the A/C down to maintain 75F-76F and use the Ilford chart linked earlier.

Wayne

 

[JohnTF]

102. We don't get into temperature dependent rate law until second semester cause you really need to have differential calculus as a prereq.

Come on, why not wait for partial differential calc?

It's a straight line, so m is constant, (the first derivative) -- never used calc in Chemistry-- it's more a physics thing for most ;-)

You did not think you were going to slip that one past did you? ;-)

Now, when processing digital images, the graphing function built in to the newest electronic brains of the newest GPS equipped cameras gives you a print out for all the film/developer combinations emulated and selected in the menu section of the camera, IOW you can select this to be done automatically and presented in the viewfinder.

John

 

[JohnTF]

Has anyone experienced reticulation in their negs from all that temperature yo-yoing (adding ice when the tempering bath warms up) , stop/fixer/wash at different temperatures - and everything way different from ambient air/water temperature)?

Had it happen a long time ago with Royal Pan 4x5, probably souped in DK60a and fixed in whatever was in the school darkroom, probably standard powder Kodak mixed in gallons.

I had somehow turned the hot water on to wash the negs, it probably soaked at least ten minutes before I paid attention, it was hot enough that the emulsion slid off the base in the corner I grabbed to pick up the film.

The emulsion firmed back up when it cooled/dried.


I don't know where the negative or any prints are, but the pattern was interesting, the cracks seemed to often follow the edges of the dark/light areas of the image.

I tried to duplicate it, but gave up after a while.

I think you need an old fashioned thick emulsion, no hardener in the fix, the hot wash -- in some combination.

I think modern thin emulsions would be difficult to reticulate as I imagine the manufacturers would consider it an advance to avoid reticulation, I even tried heating up some sheet film and putting it in the freezer, you can get some frost patterns. The areas of reticulation were probably close to a millimeter or more in size, was kind of a jigsaw appearance.

Other reticulation reactions may affect the image, but I am not well versed enough to intelligently comment,though that has not stopped me in the past. ;-)

John

 

[mackigator]

For someone like me - small batches done in 2 and 4 reel stainless tanks (sometimes months apart between developing sessions) - what is the fastest, easiest way to level off temps? I find preparing a bath at 20C to set the tanks in takes a little time and then it takes perhaps an added 30 minutes to get the temps in the containers to level off. This temp leveling ritual at least doubles my time to develop. Are there other ways?

 

[JohnTF]

To the OP, a little warm is going to affect the highlight density, but you are erring in to the area of latitude in the better direction, i.e. you are headed to where you should be able to easily correct during printing.

As you gain more experience, and wish to control your variables to a greater degree to make sure what you are doing in the camera and with your choice of film/developer combination match your intentions, --you will want to keep records and take better care of your procedures.

In summer in my darkroom, pure cold tap water, and chemistry sitting around, stay about 20 C, but it was not so hard or expensive to install mixing valves and a thermometer well in the cold side of my darkroom sink plumbing. The hot is simply hot, the cold side is plumbed from the mixing valve / thermometer well out lines, so I can see the temperature coming out of the "cold" side at a glance on the wall above the sink.

Your biggest problem would come from too cool, not a few degrees over, but it is a pleasure to print a properly exposed and developed negative as straight as possible.

I had obsessed friends who literally spent a year testing everything technical, sending the results to Ansel Adams, who wrote back it was the best technical quality he had seen, but they knew nothing about photography-- which they took as a compliment, as the image they sent was simply a set up for technique.

You can buy some gray scales and do a shot now and then on a roll to analyze how your film choice/processing/exposure is doing-- the better labs used to do this every day.

The goal is to control the variables so that you are getting what you were looking for when the shutter actuated.

Regards, John

 

[venchka]

For someone like me - small batches done is 2 and 4 reel stainless tanks (sometimes months apart between developing sessions) - what is the fastest, easiest way to level off temps? I find preparing a bath at 20C to set the tanks in takes a little time and then it takes perhaps an added 30 minutes to get the temps in the containers to level off. This temp leveling ritual at least doubles my time to develop. Are there other ways?

I use a plastic dish pan that fits in one side of my double sink. I place (4) 1 liter and (1) 2 liter bottles of water and a 2 liter bottle of fixer and my graduate with Xtol in the dish pan and fill the whole thing with water. The fixer & Xtol come from the fridge so they are at 34F. The tap water is 80F, plus or minus. Then I go load film, have a snack, watch TV, etc. until everything has settled to room temperature. Then I develop the film with enough tempered liquids to finish the process at very nearly the same temperature for all liquids. Certainly with 5 degrees or so.
I have used lunch box sized, frozen Blue Ice to speed the process, but I'm usually in no hurry.

Wayne

 

[Tom A]

My darkroom stays pretty constant 68F in the winter and - if the sun is blazing on the flat roof, about 5 degrees higher in the summer. I keep enough water in 2.5 ltr beakers to do pre-wash (when I do that) and also to mix developer and inter mediate wash. My water supply is set at 20C/68F (a 220 volt system with filtered water - a luxury that i do appreciate).
The critical part is that all the solutions are the same temperature throughout the cycle. Single shot developers (Rodinal. Xtol, d76) are a bit more sensitive to too high or too low temperature. Divided developers less so. I have found that you need several degrees difference (4-5F) to have to compensate with most films (TriX.XX etc). Slow films (Acros,PanF etc) is more sensitive to variations.
Older type films with the thicker emulsion can reticulate if you "shock" it (too cold water in the wash or intermediate wash).
If you dont have a precise control over the wash - keep one beaker with room temperature water handy -after the fix, use this and then stick the hose with the wash water in the tank and let it slowly dilute the room temperature water - less of a shock to the emulsion.
Film developing is more of a consistency process than following the "book". If you do it the same way every time - chances are that it will work all the time! One area where you dont want variables is in the darkroom!!!!!!

 

[Chris101]

Come on, why not wait for partial differential calc?

It's a straight line, so m is constant, (the first derivative) -- never used calc in Chemistry-- it's more a physics thing for most ;-)

You did not think you were going to slip that one past did you? ;-)

...

That's why I said second semester. Eventually they tell you that the straight line models you learn in 101 are more convenient than true. Here is a very clear write-up of the temperature dependence of the rate of chemical reactions:

Chapter 2 of Upadhyay's Chemical Kinetics and Reaction Dynamics, Temperature Effect on Reaction Rate

Physics can get away with lazy math - just set all the constants to one and do the arithmetic on your fingers. In chemistry, you need to run real reactions and make measurements with lots of numbers in them. So using a tool like differential calculus, you can crunch an unquantifiable mess of changing concentrations into well isolated, and measurable, variables: concentration, time and temperature.

You don't need partial differentiation because when you do the experiments, you change only one variable at a time.

 

[Argenticien]

My darkroom stays pretty constant 68F in the winter and - if the sun is blazing on the flat roof, about 5 degrees higher in the summer. I keep enough water in 2.5 ltr beakers to do pre-wash (when I do that) and also to mix developer and inter mediate wash.

So it sounds as if you, like me, are not keeping the concentrate at 68 F, so like mine it will raise the temperature of the mixing water. I was thinking about this. Suppose in summer the developer is at 73 F. I often do Ilfosol in 1+14 (cheapskate proportion). I believe that if you assume water and developer have the same specific heat capacity (which they don't, but it must be close), you can in that case simply say that the temperature of the working solution will be 1/14 of the way between the mix water (68) and the developer (73), so 68.35 F. I've always ignoring this effect and used the dev time for the mix-water's temperature (here, 68) so actually I'm not far off. (Why didn't I do this calc before?!)

Doing the same calc for Rodinal in 1:50 or 1:100, you get to 68.1 or 68.05, so the difference is truly negligible.

Fix my maths if not right -- or if anyone knows the specific heat capacity of any developers, have at it.

--Dave

 

[venchka]

Don't you have a thermometer? Why guess or assume? Measure.

Wayne

 

[Dana B.]

For someone like me - small batches done in 2 and 4 reel stainless tanks (sometimes months apart between developing sessions) - what is the fastest, easiest way to level off temps? I find preparing a bath at 20C to set the tanks in takes a little time and then it takes perhaps an added 30 minutes to get the temps in the containers to level off. This temp leveling ritual at least doubles my time to develop. Are there other ways?

Simple: ice. Mix your developer. Take its temperature. Add a cube or two of ice, if needed. Stir. Repeat as necessary till it's 68*. Rinse thermometer. Develop.

I use a four-reel stainless tank (135, or two 120 reels). Only takes a couple minutes. Works for me.

 

[JohnTF]

That's why I said second semester. Eventually they tell you that the straight line models you learn in 101 are more convenient than true. Here is a very clear write-up of the temperature dependence of the rate of chemical reactions:

Chapter 2 of Upadhyay's Chemical Kinetics and Reaction Dynamics, Temperature Effect on Reaction Rate

Physics can get away with lazy math - just set all the constants to one and do the arithmetic on your fingers. In chemistry, you need to run real reactions and make measurements with lots of numbers in them. So using a tool like differential calculus, you can crunch an unquantifiable mess of changing concentrations into well isolated, and measurable, variables: concentration, time and temperature.

You don't need partial differentiation because when you do the experiments, you change only one variable at a time.

Am pretty sure Algebra 1 will suffice for most of it, or rely on Ilford and Kodak's charts and a well calibrated thermometer. ;-)

John

 

[JohnTF]

Older type films with the thicker emulsion can reticulate if you "shock" it (too cold water in the wash or intermediate wash).

Tom, the only time I experienced it, the film went from normal to very hot, to the point that any wiping would have removed the reticulated emulsion.

As I said, years later I tried to duplicate it, and gave up, but I have not researched what other have tried.

If I ever see the negative in the very old piles, I will scan and post it, though, I would certainly not hold my breath waiting.

Have you ever seen it in your work first hand?

John