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-   -   C41 rinse water temp (http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=13240)

adrianlambert 7th June 2020 10:28 PM

C41 rinse water temp
 
I知 soon to process my first sheets in c41. Quite daunting! This will be in a jobo atl-1000 automated processor. Everything is being tested and seems to be good except the rinse water. I have two options, mains feed with thermostatic control or a tank/heater/pump combo to feed tempered water at the critical moment.

I致e been looking at the equipment for either and have seen some instantaneous hot water heaters that can be set to 38ーC. But they aren稚 100% instant. So initially water will come through the pipe for a second or two much colder.

So my question, in order to avoid reticulation or other issues, would an almost instantaneous water heater be sufficient or must every single drop of water be at 38ーC?
Thanks

John King 8th June 2020 07:02 AM

I always rinse between the developer and bleach/fixer at 38c but the final wash can be anywhere between 30 and 40.. You appear to be using a different system to myself which is in a Jobo rotary system and the final rinse is for 6 x 30 seconds with water changes ay each interval. The stabilising bath I use the chemical again at 38c but do not agitate to avoid any bubbles and possible water marks when drying.

adrianlambert 8th June 2020 07:33 AM

Quote:

Originally Posted by John King (Post 133814)
I always rinse between the developer and bleach/fixer at 38c but the final wash can be anywhere between 30 and 40.. You appear to be using a different system to myself which is in a Jobo rotary system and the final rinse is for 6 x 30 seconds with water changes ay each interval. The stabilising bath I use the chemical again at 38c but do not agitate to avoid any bubbles and possible water marks when drying.

Thank you John but I don稚 think this answers the question that I posed. Unless I知 misunderstanding something. I知 asking if, during the rinse phase, water is supplied at less than 38ーc for a couple of seconds before it rises to 38, will this be an issue.

Martin Aislabie 8th June 2020 04:09 PM

Film emulsion fractures easily with thermal shock.

So, in answer to your question - no I'm sure your first couple of seconds at wash water doesn't have to be at 38degC - but it will need to be 38 +/- 2~3C throughout the entire period - including the first couple of seconds.

One hears of many photographers who process their own film complain about grain - most are likely to be suffering from reticulation (fracturing of the film emulsion due to thermal shock)

Hope this helps

Martin

John King 8th June 2020 07:31 PM

Quote:

Originally Posted by adrianlambert (Post 133816)
Thank you John but I don稚 think this answers the question that I posed. Unless I知 misunderstanding something. I知 asking if, during the rinse phase, water is supplied at less than 38ーc for a couple of seconds before it rises to 38, will this be an issue.

Not at all. Just rinse for a few seconds more.

John King 8th June 2020 07:33 PM

Quote:

Originally Posted by Martin Aislabie (Post 133828)
Film emulsion fractures easily with thermal shock.

So, in answer to your question - no I'm sure your first couple of seconds at wash water doesn't have to be at 38degC - but it will need to be 38 +/- 2~3C throughout the entire period - including the first couple of seconds.

One hears of many photographers who process their own film complain about grain - most are likely to be suffering from reticulation (fracturing of the film emulsion due to thermal shock)

Hope this helps

Martin

I have not seen reticulation for more years that I can remember. Modern emulsions are so robust they can stand quite severe thermal shock.

adrianlambert 9th June 2020 09:44 AM

Quote:

Originally Posted by Martin Aislabie (Post 133828)
Film emulsion fractures easily with thermal shock.



So, in answer to your question - no I'm sure your first couple of seconds at wash water doesn't have to be at 38degC - but it will need to be 38 +/- 2~3C throughout the entire period - including the first couple of seconds.



One hears of many photographers who process their own film complain about grain - most are likely to be suffering from reticulation (fracturing of the film emulsion due to thermal shock)



Hope this helps



Martin


Thanks Martin

This response being the more conservative is the one I知 inclined to consider. So I値l forget about the in-line electric water heater and stick with the heated water tank and pump. But also clear any water from the lines so that when it comes through to the film tank it値l be at temp (minus the initially thermal losses from the lines).


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adrianlambert 9th June 2020 09:46 AM

Quote:

Originally Posted by John King (Post 133838)
I have not seen reticulation for more years that I can remember. Modern emulsions are so robust they can stand quite severe thermal shock.



Thanks John, I知 going to be super careful with my processing and maybe try a less careful approach when I have some film that I知 not too concerned about. If your suggestion works out then maybe an inline water heater would work well.


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adrianlambert 9th June 2020 09:48 AM

Quote:

Originally Posted by John King (Post 133836)
Not at all. Just rinse for a few seconds more.



Unfortunately this isn稚 an option when using the JOBO ATL-1000 as all of the programs are pre set.


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