Chemical temps.

G

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Twenty three years ago when living and doing my film myself in England, my problems were keeping the temps when film processing at a constant 68f because it was always cold, summer was the only easy time for the work.
Now I am living in the south of the USA. Today I am doing my first BW film processing, my cold water tap temp is 72f, my fridge water is 54f.
So how do you chaps control your temps in the heat because there is no way the tank is going to keep that temp for 14 minutes of me turning it.
Fill the bath or sink at 68f is that how you do it ?
 
Some developers (e.g. Diafine or Thornton's 2-bath) are not all that affected by temperature. Just a thought.
 
I use a small 6-pack cooler with water at 68F. The insulation is good enough to maintai a contant temperature for typical development times.

In fact, I also adjust the temperature of the tank containing only the film. I do this for about 15 minutes before adding the developer, checking the cooler water temperature every once in a while and adjusting as necessary. I then check and adjust the cooler water temperature right before adding the developer. The attached lid of the cooler will hold down my large (4-35mm reel) tank and keep it from floating. For a smaller tank, another small tank filled with water and placed on top of the tank with film will prevent flotation. Once chemicals are added, the tank won't float in the cooler.

I think this has improved my results as this prevents developer temperature change due to the tank initial temperature.

I started doing this for black and white after I used this approach for color developing, where temperature control is more critical.

Of course using stainless steel reels and tanks is essential.
 
Don't fight it. Just go with 72 degrees and shorten time a bit. There are charts available for temp compensation.
 
If you have already dialed in a process at 68 degrees simply start at 66 and let the temp rise to 70 during the 14 minutes. Or, whatever averages your 68. I am sure you know that you can make just about anything work so long as you do it consistently.

I live in central FL and process at 68 year round. Since I always use one shot developers (Rodinal & HC110 Dil H) I just stir in ice cubes until I hit the desired temp. If I get it too cold, just add tap water. Then I pour out excess water until I get to the desired volume, dump in developer, mix and go.

FWIW, I always stop with tap water, sometimes 80 degrees. Never seen any ill effects.
 
I develop anywhere from 68 to 75, depending on how easy it is to get the water temp right. Chemical temp is easy to change, but you need the wash water to be the same as the chemicals to prevent reticulation. Kodak, Fuji, and Ilford publish developing times for their films at different temps (Kodak gives times for 68, 70, 72, 75). So, its easy to choose any temp that you need.
 
developing time (corrected) = developing time (original) * e(-0.081*(Temperature corrected - Temperature original))

The above formula is implemented into the Iphone application "dev chart" and works very well given the other variables are kept constant (agitation & dilution).

Personally, after having experimented with cooling and warming of developer solutions, I find it easier to compensate dev time over changing temperatures.
 
maddoc said:
developing time (corrected) = developing time (original) * e(-0.081*(Temperature corrected - Temperature original))

The above formula is implemented into the Iphone application "dev chart" and works very well given the other variables are kept constant (agitation & dilution).

Personally, after having experimented with cooling and warming of developer solutions, I find it easier to compensate dev time over changing temperatures.
Click to expand...

The problem with equations like that, and with the Ilford time-compensation chart that someone posted earlier, is that every chemical formulation has a different time/temp curve. In other words, the amount of compensation for a temperature change varies from one developer to the next. The generalized equation makes a good starting point if you do not have more exact info for the developer/film combination you are using, but I know from experience that using it on important pictures without prior testing can be risky :bang:
 
OK, this comes at an apropos moment.

I have been developing for a few weeks so far, all neopan (legacy) 100 and 400. At the beginning my tap water was almost exactly 20 C, so all was cool.

Today I developed a roll of Efke 50. Most of the images were low-light/long exposure, and were hard to meter properly (currently my only trustworthy meter is my little Leica MR). Also, my tap water temp has risen to almost 23 C !

The dev chart said to reduce time from 8 min to 6 min. That felt a little extreme, especially since I was afraid frames could be underexposed, so I went with 7.

Well, looking at the negative, a lot of frames do indeed look underexposed - some look OK.

You guys with years of experience at this - what approach would you take? I think I should have left the time at 8 minutes.

BTW, someone mentioned that you can adjust temp in the Dev Chart iPhone app - where? I see no way to do so in the main interface, nor in the prefs.

Thanks!

Randy
 
To cool down chemicals I use re-freezable ice cubes. They don't dilute your chemistry and you can wash and reuse them. They can be found at most garden variety general stores. You can also use plastic 35mm film canisters filled with water and frozen.
 
I spent a year living in a loft in a small city in rural Tennessee. The temperature in my darkroom was regularly over 90 in the summer (couldn't afford an air conditioner, living the starving-artist-in-a-garret life, very glamorous.) I'd get a bag of ice and let it melt in a styrofoam cooler, dipping my developing tank in for a few minutes as I agitated. Then I'd print with one tray floating in another, surrounded by melting ice. Getting nostalgic here....
 
Randy, to change the temperature in the Iphone application (I have the older, non-upgradable version from last year June) you first have to add a film / developer combination to your favorites with the star symbol in the upper right. Then click "editing" and the menu expands, showing more menu items. Then click "temperature" and in the opening new menu active temp time conversion (don`t remember the exact term) with the slider button. You can then change the temperature with the wheel and the time changes.
 
maddoc said:
Randy, to change the temperature in the Iphone application (I have the older, non-upgradable version from last year June) you first have to add a film / developer combination to your favorites with the star symbol in the upper right. Then click "editing" and the menu expands, showing more menu items. Then click "temperature" and in the opening new menu active temp time conversion (don`t remember the exact term) with the slider button. You can then change the temperature with the wheel and the time changes.
Click to expand...

Gabor, thanks so much - I see how to do it now.

Do you trust the recalibrated times? Are they specific to each film, or just derived from the standard chart I ran across?

In my case I think I should have pushed the development longer since I may have underexposed, but for normal exposure to you think the conversion works?

Randy
 
Oh my... I don't pay that much attention to +/-2C changes in temparute during developing, but from that chart it looks like each degree requires upto a minute of time compensation :eek: :bang:

Sigh, I need to revise my developing techniques :(
 
I've tried to cool tank and put reels into right defore pouring developer into. I've tried to pour developer while it's at 18-19C and develop for full time. I've tried to pour developer at 20C and cut time to compensate. I stick to latter two but method #2 probably is more comfortable for mind to see average temp has been 20C and I've kept normal time (OK, normal is not the right word...but you get idea).
 
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Randy,

in case of doubt, the recalibrated times for different temperatures are much more precise than required for us amateurs working under otherwise uncontrolled conditions at home. The usual developer have enough tolerance in their formula to compensate for derivations from theoretical "ideal" conditions.

So yes, the temperature conversions works excellent for all film / developer combinations that I have used so far with this method (74 different film developer combinations) and is easier to control and reproduce than trying to maintain a certain temperature without sufficient equipment. :)
 
maddoc said:
Randy,

in case of doubt, the recalibrated times for different temperatures are much more precise than required for us amateurs working under otherwise uncontrolled conditions at home. The usual developer have enough tolerance in their formula to compensate for derivations from theoretical "ideal" conditions.

So yes, the temperature conversions works excellent for all film / developer combinations that I have used so far with this method (74 different film developer combinations) and is easier to control and reproduce than trying to maintain a certain temperature without sufficient equipment. :)
Click to expand...

That's very helpful advice. But to clarify, since the developers have some tolerance, do you worry if the temperature deviation is less than two degrees?

Like another poster, I was a little stunned that this small variation took two minutes off the spec'ed time!

Thanks!

Randy
 
Randy,

I take temperature readings as exact as 0.5℃ at home and start the timer quite at the same moment as I start pouring developer into the tank. Other than this I follow the times published at the dev chart and also use the same agitation as published there. A deviation of two degrees will be visible but you get still usable negs given the other parameter are correct.
 
Rather then trying to get the water from the tap to a certain tempt I just keep a couple of gallon jugs of water available. That way all my chemical plus water for rising are all at the same temp, usually 68-72 degrees depending on the time of the year. For odd number tempt I just use the time for the next higher tempt IE 71=72. Found on the Kodak or Ilford PDF for the film and or developer used. For the final wash rather then using running water I've found the following to work quit well
Fill tank with water, Invert 20 times let sit for 5 mins then empty
Fill tank with water, Invert 15 times let sit for 5 mins then empty
Fill tank with water, Invert 10 times let sit for 5 mins then empty
Fill tank with water, Invert 5 times let sit for 5 mins then empty
Kodak Photoflow 30 second
Hang to dry.

Note: I normally use XTOL which last me about a two months for Stop bath and Fixer, and photoflow I generally mix a new batch after every 8-10 tanks (distilled water is used for mixing)
 
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