Ignoring density, what difference do temps make with B&W developers?

At room temperature say I 1) Develop the film leader in room light, noting the time for it to get to the density I want, then 2) develop the film for the same time.

fwir, this should give me consistent negative density. (Close enough for government work.)

I'm curious about what differences in room temperature will do. Alter contrast/grain/whatever?

I've got thermometers and have experience doing everything at 68'F but some friends are showing an interest in film photography, so is my 7 yo granddaughter.

What I'm looking to do is have a .darkroom in a shopping bag'. Chems, tank and changing bag etc. They shoot a roll with one of my cameras and it gets processed at their place. For a first timer, watching the leader go dark seems a lot less fuss than getting the chems to 68'F but I'm wondering what the downside is.

John51 said:

At room temperature say I 1) Develop the film leader in room light, noting the time for it to get to the density I want, then 2) develop the film for the same time.

fwir, this should give me consistent negative density. (Close enough for government work.)

I'm curious about what differences in room temperature will do. Alter contrast/grain/whatever?

I've got thermometers and have experience doing everything at 68'F but some friends are showing an interest in film photography, so is my 7 yo granddaughter.

What I'm looking to do is have a .darkroom in a shopping bag'. Chems, tank and changing bag etc. They shoot a roll with one of my cameras and it gets processed at their place. For a first timer, watching the leader go dark seems a lot less fuss than getting the chems to 68'F but I'm wondering what the downside is.

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For a first timer it is important to learn to work methodically, i.e. time and temperature. Once competence and confidence are gained, this can be used as a point of deperture.
My quibble with the "watch the leader" method is that it indicates a time to develop for solidly blocked highlights, massive overexposure.

Insofar as it affects development time, extremely short development times could result in uneven development. Longer times with sufficient rest periods allow your shadows to develop. If we're talking room temperatures, and you're not in Satan's parlor or visiting Eskimos, I think any practical differences would be negligible.

That said, I wouldn't rely on a visual clip test to gauge development time. It's good for determining if the developer is alive and maybe for finding a minimum time, but there are too many other variables at play for this to work as a casual test.

I think you want Diafine.

7 years old is to young to be around those chemicals, she will be eye and nose level with the table and way to easy to get splashes or dust in eye, ear or mouth or hands.

hello john51
what i always do is process with chemicals at room temperature
i store all my film at room temerature as well.
i was taught long ago before processing anything important, process a test roll or test sheet
to determine if the development time is adequate or too much.
( i do this sometimes when i have to drive someplace important too > dry run )
so rather than process 2 handfulls of film i'd process 1 sheet. or 1 roll ...
besides, its only an extra few mins, you should be able to look at the film after 30-40seconds in the fixer
unroll a little bit inspect in the light and proceed as planned.
the thing i would also be concerned about, aside from uber-short developing times / uneven development
is how much you exposed your film in camera. as you know its a funny dance bewteen exposure, time and developer.
i tend to enjoy giving my film a nice blast of exposure and a nice blast of development ...
around little kids you might consider using a coffee based developer
they are made of instant coffee vit c and washing soda
( or if you do the conversion / weight calculation baking soda ) no harmful ingredients ...
there are handfuls of blogs on its use as well as the caffenol-cookbook.

I always develop at room temperature.
Just adjust the time accordingly. The manufacturer's datasheet or the Developing Dial in a Kodak Darkroom dataguide will give you the times.
A seven year old may be safe around developing chemicals, if they are fairly mature and with a careful adult.

John, did you consider Diafine or a mono-bath? When my kids were small (a bit older but not much) I cobbled up some of Crawley's mono-bath as a demonstration of B&W development. Any of the 2-bath developers would do.

I process at room temperature, but the room temperature in my darkroom varies between 20 C (summer) and 22 C (winter), so ... . I do comepnsate with development time in winter, but not completly. In my experience, a few degeres C will not affect the printability of the negatives. The biggest deviation I had was + 4 C, and these negative did come out too hard and dense - for my taste. So I try to process at a temperature between +0 C and +2 C after compensation.

Why don´t you take along a thermometer and measure the temperature of your developer, so you can compensate?

Developing the leader at daylight will be nice to see for the kids, good idea. But for developing the film, I´d just use the time provided for by the data sheets / massive dev char.

Ilford publishes a chart for compensating development times, which will provide a good starting point with most developers. I printed it and sticked it to the door of my darkroom. The link is here: https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Temperature-compensation-chart.pdf

I develop at room temperature unless it is so warm that the development time is less than 5 minutes. In that case I chill all the chemicals before I develop the film.

You can adjust time for temperature within reasonable limits, but I wouldn’t use the leader test except to make sure my developer hasn’t crashed since I last used it. The leader is likely to have much more exposure than the lightest highlights in your image exposure and may even be solarized from overexposure.

If you have a smartphone, the Massive Dev Chart app can calculate your time/temp adjustment easily, and you can put in your own initial time/temp combo based on your own results. Most film and developer instruction sheets include a time/temp adjustment chart.

I process at room temperature with replenished developer or at the tap water temperature with one-shot developers, which is usually about 72F here in Honolulu.

mike c said:

7 years old is to young to be around those chemicals, she will be eye and nose level with the table and way to easy to get splashes or dust in eye, ear or mouth or hands.

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I told her what you said and she gave a very stern look. Consider yourself reproached.

John51 said:

I told her what you said and she gave a very stern look. Consider yourself reproached.

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And well she should. I would suggest that certain things we have around the house to clean the oven, unclog drains, and kill weeds are far more hazardous. Not only is it possible to process film for a spectator without making a splashing mess, but I think you'd actually have to go some effort to do so. Rubber gloves and goggles are fun to wear when you're seven if she wants to participate. And I don't keep drinks in the darkroom, ever. A little common sense goes along way.

check the films data sheet... they usually include that information. kodaks tmax films have nice graphs showing development curves in relation to temps and times.

bvy said:

And well she should. I would suggest that certain things we have around the house to clean the oven, unclog drains, and kill weeds are far more hazardous. Not only is it possible to process film for a spectator without making a splashing mess, but I think you'd actually have to go some effort to do so. Rubber gloves and goggles are fun to wear when you're seven if she wants to participate. And I don't keep drinks in the darkroom, ever. A little common sense goes along way.

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OKay, but still be careful, 7 year old can be very spontaneous , and most are nose level to the sink.

I would think, though I don't know for sure, that warmer developer is more active so it is like an accelerator and seems to me that it would affect the high densities more than the low densities.. so it would increase contrast a bit.

dpurdy said:

I would think, though I don't know for sure, that warmer developer is more active so it is like an accelerator and seems to me that it would affect the high densities more than the low densities.. so it would increase contrast a bit.

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Higher temperature does increase the activity of the developer, but not more in the highlights than the shadows. Developing at a higher temperature is analogous to extending development time. If one compensates for the higher temperature with a shorter time, there should be no difference in the resulting negatives. Graininess and sharpness will stay the same too. Some developers lose activity at low temperatures, but that's not the issue here.

@OP. Find the recommended developing times for the films and developers you are using then adjust that for the ambient temperature according to the Ilford compensation chart linked to above. You should be good to go.

Best,

Doremus

Doremus Scudder said:

Graininess and sharpness will stay the same too. Some developers lose activity at low temperatures, but that's not the issue here.

Doremus

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Apparent graininess and sharpness will only remain the same if the whole process cycle - developer through to washing - is kept within +/- 1ºC particularly at higher temperatures, some films are more susceptible than others to temperature shifts, and choice of developer can be and issue.

When in Turkey I process at 27ºC there's no quality difference between these negatives and those processed at 20ºC when in the UK.

Ian

Ian has a point, of course. If you're processing at ambient temperature and your wash water is significantly cooler, then there can be problems.

When I develop film at higher ambient temperatures, I mix my developer, stop and fix with tap water adjusted to the ambient temperature. Wash water is also adjusted to match so that the whole process is done at one easy-to-control temperature. Like Ian, I haven't seen any increase in graininess, etc. in negatives processed at higher temperatures from negs processed at the lab-standard 20°C.

Best,

Doremus

Ian and Doremus point out that all the chemicals should be about the same temperature to avoid film reticulation.

If I've understood correctly, as long as development time is adjusted to suit the room temperature, there isn't much difference to the end result.

All of that time I spent in the past getting everything up to 68'F could have been avoided by simply measuring room temps and reading the correct time from a chart.

Or am I missing something?

You have it about right. You should measure the solution temperature, but if you let the developer stand for a couple of hours, room temperature is close enough.

Higher temperature makes the developer more active, and for a given development time you get more contrast and a bit more density with higher temperature. You correct for this by reducing the development time.

John51 said:

All of that time I spent in the past getting everything up to 68'F could have been avoided by simply measuring room temps and reading the correct time from a chart.

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If you want to know the temperature of your developer, measure the temperature of your developer. I guess my point is, don't take a reading off of the thermostat that controls your room/house temperature and assume that's your processing temperature. It should be close, but it likely won't be exact.

I have a digital meat thermometer, cost about £3.50. The same thermometer for hydroponic use is £8.50 but if you want to do film processing with it, it costs £12.50.

It's important to keep the temperature consistent from pre-soak to final rinse. This not only prevents reticulation (which rarely occurs with modern hardened-emulsion films), but grain clumping and "micro-reticulation," which can increase the apparent graininess. This is increasingly important the smaller the film is. It's not difficult to do this, but a few comments anyway:

If you base your developing time on the ambient temperature, you have to make sure you mix your solutions (and have your wash water) at that temperature as well. Even so, solution temperature will usually vary a bit from air temperature due to evaporation or whatever. Best is to measure the temperature of a solution that has stabilized and use that temp. If your solutions are different than the air temp, the times will be wrong.

If you base your developing time on the temperature of your tap water, and this is significantly different than the air temperature, the temperature of the solutions will slowly drift. This is a lot slower than most people think, but by the time you get to the wash stage can be a couple of degrees off, so check and adjust the wash-water temperature. This same applies to mixing everything to 20°C and then developing in a warmer environment; by the end of the chain the solution temp will have risen somewhat.

Another consideration for those that mix new developer every time at 20°C, but have stop and fix at room temperature. Do make sure that the temperature difference is not too great. If so, it's better to mix the developer warmer and consult the temperature-conversion chart.

Using ambient temperature is a good way to stabilize temperatures throughout as long as the running-water and solution temperatures can be kept in line with air temperature. If not, e.g., if the tap water used to mix solutions and wash with is warmer than the air temperature, or one mixes and uses solutions at 20°C in a really warm environment, then there will be some drift which needs to be taken into account before plunging the film into wash water which is a lot warmer or colder than the last solution.

FWIW, meat thermometers are great in the range of rare to well-done roasts, but are probably pretty inaccurate around 20°C... Better to get a decent thermometer designed for measuring liquid temps in the range you are processing at.

Best,

Doremus