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#1
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Film developing temperature
The one aspect of film processing which causes me anxiety is developer temperature in the Paterson tank. I always ensure the developer is at exactly the correct temperature, but if I put a thermometer into the tank, it has immediately lost anything up to 2 degrees just through being poured in...
Any thoughts on this? |
#2
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Edmund in b&w it isn't generally a problem for me but I am helped by having a darkroom in the house where the ambient temp is always around 20C so the tank is at room temp and the developer stays at room temp.
The problem arises with colour where the most primitive way is a water bath at a couple of degrees higher than 38C but which needs topping up if you do more than say one film given the time needed. The simplest method I have seen is the famous thermostatically controlled Sous Vide in a water bath. I don't have one as I have a Jobo processor but they seem pretty good from all reports I have seen. Just as a point of information for all. When we had that incredibly hot spell last week the darkroom was at about 28C but I experimented with a tank full of 20C water and in the course of 12 mins it only rose about 0.6/75 C So even at the extreme in the U.K. and for 20C only a small adjustment in time is required in a room that is about 28C What I haven't done is try to see what the drop is when 38C is needed for 3 mins 15 sec I must give this a go to see what happens Mike |
#3
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Edmund, the temperature of your developer will drift towards room temperature whilst you are processing, but for PanF my dev time is only 7 1/2 minutes. My kitchen is probably not far of 20C most of the time, so the temperature gradient is small (either way), with not long for the temperature to change. I get perfectly good results.
I see 5x4 as a bigger problem, using open trays. That produces a large surface area for heat exchange so the dev will very quickly equalise with the ambient temperature. I just wouldn't process 5x4 in a tray in a cold room as I know I'll have no idea what the average temperature was by the end of the processing time. The good news is that if your room is more or less the same temperature most of the time, you will probably have built an allowance for temperature drift when you where establishing your ideal development time. Are you producing consistent results? |
#4
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I made a temperature controlled water bath with a storage box like this
https://www.plasticboxes.co.uk/12-li...ndle-lids.html with an aquarium heater like this and an aquarium pump like this I put enough water in to cover the heater then put in my empty film tank, developer bottle, stop solution bottle, fixer bottle and rinsing water, and wait for everything to come to the required temperature. After inversions, I put the developing tank back into the waterbath. Pete |
#5
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My darkroom is an annexe to the garage and can get very cold in winter.....around 6 or 7 degrees at times.
When processing sheet film, i have the chemicals heat up in my Jobo.....leaving it on for a couple hours with the pump running to bring the chemicals up to temp. Lately, i've been using a Paterson Orbital which sits in a dev tray of water, sitting on a tray warmer. The tray warmer is set to bring the water jacket up to 22 ˚C and once the films in the Orbital, i sit it in the water jacket to heat it up before starting to process. Seems to work well for me. If you're using a Paterson reel tank, you could consider a pre-wash for 5 minutes to bring the tank internals up to temp before starting with the dev. Of course sitting the tank in a water jacket will help minimise the loss of heat over the 5-15 minutes that your developer is in the tank. Mike |
#6
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Edmund if your darkroom is not in the house and subject to "normal" room temperature then an aquarium heater that High Sierra has linked to is a great idea. The only caveat is that if you have colour in mind at 38C then the aquarium heater won't get the temp high enough as it is a fish heater and not fryer
If it is only b&w then of course ignore what's needed for 38C but as you have kindly replied on the N&T C41 kits I suspect it is C41 you have in mind. I note that the aquarium heater goes to 32C and maybe the N&T kit is designed for developing at less than 38C At less than 38C there is the perennial question: Does using a lower temperature risk colour crossover and even if it does will it be bad enough to be seen by any but the most discerning eye I just don't know. There are those "traditionalist" who say that less than 38C is inviting disaster and others who report no problems. When I have asked various questions such as : what is the evidence that less than 38C give problems and what is the frequency of those problems and is there a correlation between frequency and temperature no-one seems able to point me towards any source of evidence and yet I presume that tests by the likes of colour chemists have been done - otherwise why is there a standard temperature. This must have been presumably arrived at scientifically If anyone knows of such evidence that is available then first prize is an evening in my company if they can tell me where it is. If you can suggest possible sources only but not definitive evidence then that's second prize which is two evenings in my company Mike |
#7
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Quote:
But now I know where to go if I or others need some in the future. Terry S |
#8
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Quote:
https://www.ag-photographic.co.uk/no...tat-2545-p.asp Pete |
#9
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I'm sorry but these replies kind of miss the point of my post:
I use one of these for C41 processing - https://www.theimagingwarehouse.com/...ssors/ANFP-D21. - I was kindly given it by a forum member. It even has a combined temperature control and 3 stage timer attached. So the water bath isn't the problem. The chemicals are all at the right temperature, and for C41 I tend to just use the twiddle stick rather than inversion, to avoid losing heat. What I am describing is that the act of pouring the developer into the film tank immediately loses at least 1 degree. So the development actually starts at too low a temperature. I was wondering how other people overcome this effect. Or has no-one else has checked the film tank temperature immediately after filling? Last edited by EdmundH; 1st July 2020 at 11:38 PM. |
#10
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Good Morning Edmund.
That looks like a fine set-up for colour work. I didn't appreciate from your first post what your specific concern was. However, if I were you, I'd consider making the developer 1 degree warmer before pouring it in to compensate. I'd run half a dozen rolls that way, then compare results to what I was producing previously. If I saw an improvement I'd carry on making the dev slightly warmer by the same fixed amount, and if the results were indistinguishable then I'd be reassured it wasn't really an issue. Good luck. |
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