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  #11  
Old 2nd July 2020, 08:29 AM
John King John King is online now
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Originally Posted by EdmundH View Post
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?
I use a JOBO processor so I don't have the problem. However before I start the processing I load the tank with film and put it to one side.

I put cold water into the processor and warm it up with the ready mixed chemicals in the measuring beakers and at the same time float the dev tank in the water until it is at the operating temp. That ensures the developer goes into an already warm tank so the drop in temperature does not occur.

So in your case float the dev tank in the waterbath for no less than 10-15 mins and that should be enough to warm the tank.
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Old 2nd July 2020, 10:01 AM
EdmundH EdmundH is offline
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Originally Posted by John King View Post
I use a JOBO processor so I don't have the problem. However before I start the processing I load the tank with film and put it to one side.

I put cold water into the processor and warm it up with the ready mixed chemicals in the measuring beakers and at the same time float the dev tank in the water until it is at the operating temp. That ensures the developer goes into an already warm tank so the drop in temperature does not occur.

So in your case float the dev tank in the waterbath for no less than 10-15 mins and that should be enough to warm the tank.

Hi John, this is exactly what I do, but there is still a measurable temperature drop in the developer temperature. However you wouldn't have the opportunity to measure it in a Job processor.
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  #13  
Old 2nd July 2020, 10:06 AM
EdmundH EdmundH is offline
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Originally Posted by skellum View Post
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.
Hi, that has been my conclusion, although it backfired recently. The ambient temperature was so high that the developer ended up too warm, and the negatives were 'a little dense'!
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Old 2nd July 2020, 07:49 PM
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Martin Aislabie Martin Aislabie is offline
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Originally Posted by EdmundH View Post
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?
If your darkroom or development tanks are below the 20C target temperature, you could try using a tempering bath to pre-soak everything to the correct temperature before you start.

You might want to leave the tank (and all of your chemicals too ?) in the tempering bath for perhaps 20 min to get it to the correct temperature.

A kettle full of warm/hot water to help maintain your tempering bath is a great help.

A tempering bath also works in hot weather too - preventing all the temperatures from drifting high.

Depending on the temperature of your cold tap water, it sometimes pays to prepare a few litres of tap water and put it in the fridge overnight.

I never put any developer/stop/fix in the fridge - just tap water.

Martin
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Old 2nd July 2020, 08:33 PM
John King John King is online now
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Originally Posted by EdmundH View Post
Hi John, this is exactly what I do, but there is still a measurable temperature drop in the developer temperature. However you wouldn't have the opportunity to measure it in a Job processor.
If you are certain the temperature drop is always 2 degrees C Instead of setting your developer temperature to 38 C change it to 40c and see how you get on.

You could always do a dry run first with a damaged film in the tank and by using plain water at 40c check the temp after a few mins to see what it is resting at.
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Old 2nd July 2020, 09:52 PM
EdmundH EdmundH is offline
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Originally Posted by John King View Post
If you are certain the temperature drop is always 2 degrees C Instead of setting your developer temperature to 38 C change it to 40c and see how you get on.

You could always do a dry run first with a damaged film in the tank and by using plain water at 40c check the temp after a few mins to see what it is resting at.

John, Thanks for the dry run idea! That way I’d know for certain whether the temperature was going to be correct before committing.

I suspect that this is a case of ignorance being bliss; if I had just assumed that the temperature was correct, then I wouldn’t be worried. At the end of the day I guess it’s mostly a matter of consistency.


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