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Developing B&W negatives at 18 deg C instead of 20... newbie questions

I have never used Rodinal, so I will throw out a question for others to answer. You say that you leave the solution to stabilise at room temperature. If your tap water was pretty cold, that might be an overnight job, I guess. So my question is: Does a 1:50 working solution of Rodinal suffer from standing around for that length of time - for instance, does it oxidise?

Personally, I aim to develop at 22 deg C. My tap water is pretty cold in winter, so I use a water bath at about 40 deg C to get solutions (and tank) up to about 21.5 deg C, then change the water to a 22 deg mix. This needs a little kitchen skill because of the thermal reserve of the plastic containers. If in fact the solutions are a little off the 22 mark when I start, I adjust times as per the Ilford time/temperature chart.

I also keep a reserve of 22 deg water for the first wash after fixing, to cushion the shock between processing temperature and tap water, and thus avoid the risk of reticulation.

But having read the brilliant idea in post #25 above, I think I shall be looking out for a small dead refrigerator ...
 
There is absolutely nothing wrong with processing at 18C. I do it sometimes...even at 15C as couldn't be bothered to take the time and energy to heat up my darkroom to 20C. I've even left the tank in the fridge over night!
 
snusmumriken said:
You say that you leave the solution to stabilise at room temperature. If your tap water was pretty cold, that might be an overnight job, I guess.
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Leave the water out for a while. After it comes up/down to temperature, then you mix up your working strength developer.
A plastic or metal container for water will come to room temperature fairly quickly. If you use something like a pail, you will have enough for mixing stop bath and for at least the first part of the wash as well!
 
A cooler would do the same if you can get your water to 22º first. Or maybe the light bulb trick, just put it in the cooler in a small fixture or old lamp.
 


Yes, this is what I've been doing. I fill several re-purposed 2 litre plastic mineral water bottles with tap water. After a few hours (probably much sooner) it's at room temperature, after which I mix my solutions for immediate use, with plenty left over for Ilford-method washing. More recently, my final wash is with bottled distilled water which is stored at room temperature by default (plus a couple of drops of wetting agent).
 
If you have two less cups of tea or coffee a day you will have enough hot water to heat your chemicals to a proper temperature, or turn the heating down and wear a fleece and then boil a kettle. But second guessing reliable temperature ranges gets you into the area of saving a bit on the electricity bill and losing the value you've placed in your film. Which is more wasteful, processing a roll of FP4 badly or boiling a kettle? I rest my case.
 
250swb said:
If you have two less cups of tea or coffee a day you will have enough hot water to heat your chemicals to a proper temperature
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True.
With B&W, 18C is a proper temperature.
 
MattKing said:
True.
With B&W, 18C is a proper temperature.
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I'm struggling to find that in the Massive Dev Chart with the OP's Fomapan 200. In fact there are very few film and developer combinations in the 18C range, not that anybody should be a slave to convention. But film emulsions are like exposure, there is a 'reciprocity' involved for processing at lower temperatures just as there is in making longer exposures, and I think the only answer is to experiment against a datum negative and then come back and say 'hey, look what I did!'.
 

Thanks for that. Mercifully, I'm not concerned about the energy costs of one boiled kettle a day just yet... but I would be interested to know whether 18C is definitively an unacceptable / unwise temperature at which to develop reliably, or if it's just the case that it's not the most-commonly-used 20C standard, hence folks are (understandably) wary...
 
250swb said:
I'm struggling to find that in the Massive Dev Chart with the OP's Fomapan 200. In fact there are very few film and developer combinations in the 18C range, not that anybody should be a slave to convention.
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Isn't that because the most commonly used reference temperature is 20C? There aren't many film plus developer combinations for greater than 20C either, but I see a number of folks developing successfully at such temperatures. Do you feel the 20C references in MDC - combined with use of its time / temp converter tool (or Ilford chart on which I believe it's based) - are likely to be unreliable?
 
I repeat - 18C is fine.
You can use the adjustment calculator on the MDC site (or the dial in the Darkroom Dataguide) to convert from the 20C times.
You would need to test if you intend to use something significantly lower - some developers are more temperature sensitive than others.
 
titrisol said:
A good digital thermometer is a god investment, they are very cheap these days
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Digital isn't necessarily any more accurate than analog, it depends on the calibration. I bought a glass/ spirit type thermometer from a scientific supply place and it was surprisingly affordable. Actually made in UK and it was $7 CDN/£4.75.
 

developing at 18C will not cause a problem and the chart is fairly reliable. You can trust it for making a first attempt and then adjust to taste.
 

Thanks, Matt. Significantly lower than 18C and developing film will be the last thing on my mind
 
FWIW, my 1940 Kodak reference handbook uses 65F (18.33C) as the standard.
With B&W, as long as you are within a fairly wide range, repeatability is more important than any particular target temperature. B&W is both rewarding and fairly forgiving that way.
With colour, it is different. That is because one is essentially developing three different parts of the emulsion at the same time (the three colours) and if you don't use the right temperature, they don't develop together in the same ways.
 
250swb said:
there is a 'reciprocity' involved for processing at lower temperatures
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This is not an accurate comparison. Reciprocity failure works differently and has a different effect on a typical image than reduced developer activity. Especially with a deviation as small as 2C from the usual 20C it's perfectly feasible and easy to compensate for the lower temperature. There is no influence on tonal relationships as is the case in a reciprocity failure scenario.
The fact that 20C is the standard is pretty much just a coincidence; it might as well have been 18C from the get go. 20C just happens to be a convenient compromise between development time and ease of keeping processing chemistry at temperature in a typical indoor space in the temperate zone where most of the photography r&d happened to have taken place.
It's of course perfectly easy and viable also for OP to do his processing at 20Cbut there's nothing inherently problematic if he wants to do it at 18C. No need for any Fear, Uncertainty and Doubt.
 
Thanks to everyone for your kind, informative and interesting feedback. Very much appreciated.

I'm going to try developing at my ambient room temperature of 18C with the MDC time / temp converter (or Ilford chart) compensation for now, and will see how I get on!
 
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The Massive Development Chart app has a time/temperature conversion for each developer/film combination. Also, I haven't processed any in a while, but I think Bergger Pancro 400 is recommended to be processed at 24ºC when pushed.
 
Temperature Coefficient of Developers

The Influence of Temperature

As is the case with most chemical reactions, and photographic is a chemical reaction, the rate of development depends upon the temperature. The higher the temperature of the developer the more rapid and energetic will be the progress of development. This rule holds good for all developer substances but the actual degree of acceleration for a given rise of temperature varies with the different developers.

The increase in speed of development with an increase of 6ºC. is taken as the Temperature Coefficient of the developer. For example if we find that a particular developer works twice as quickly at 24ºC. as it did at 18ºC. then we say that it has a Temperature Coefficient of 2. A rough guide to the three main types of developer are; Temperature Coefficient of 1.8 for standard MQ developers, 1.6 for fine grain and 2.3 for super fine grain developers.

13ºC MQ 10 min, Fine Grain 19 min, Super fine grain 50 min.

18ºC MQ 6 min, Fine Grain 12 min, Super Fine Grain 25 min.

24ºC MQ 3½ min, Fine Grain 7 min, Super Fine Grain 12 min.



Developing by Jacobson and Jacobson, eighteenth edition, updated 1980, page 72

The above is almost word for word, with slight abbreviation.
 

You should be absolutely fine at 18°C and your washing method should be fine. I use purified water and a bit of Kodak Photoflo, if you are using a wetting agent you need enough to change the surface tension of the final rinse.
Matt King has a recipe for diluting Photoflo with alcohol that makes it easier to measure and handle in small doses.
 

I disagree with the "rubbish" characterization - it is a hockey themed self -portrait!
 
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