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  #1  
Old 30th May 2014, 02:39 PM
jeztastic jeztastic is offline
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Default Forgot bleach step - possible to bleach now?

Just going through some old exposed films and processing them. Put the bleach and fix in the wrong jugs and swapped them - doh! Is it possible to go back and re-bleach them now? They are too thick to even scan unfortunately.
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Old 7th June 2014, 03:38 PM
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Bob Bob is offline
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Ouch!

Not sure, but I suspect that once the fix has done it's job, the fat lady has sung and the show is over. Someone else may know for sure tho....
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Old 7th June 2014, 04:31 PM
Mike O'Pray Mike O'Pray is offline
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Welcome to FADU. Like Bob I am not sure about the chances of a recovery. It is an ever present danger and maybe I have been lucky not to fall into the trap, using blix instead of bleach then fix.

There's a school of thought that says bleach then fix in film processing aids longevity but it doesn't seem to be a universally held belief.

I'll let you know what, if anything has happened to my "blixed" films in say 25 years time. You may have to be patient that day as it will be my 100th birthday and the telegram from the then King and the riotous party I hope someone is planning may take up most of the day

Mike
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Old 7th June 2014, 04:56 PM
Lostlabours Lostlabours is offline
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Yes you can still bleach them and it'll be no different to normal after. Just pre-soak then Bleach as normal and then fix & wash.

There was a technique called looping used by astronomers who would process in colour dev & then fix, wash, bleach in a rehalogenating bleach expose to light and redevelop in colour dev this amplified the colour image, they would do this a number of times before finally bleaching and re-fixing.

Ian
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Old 7th June 2014, 05:23 PM
JOReynolds JOReynolds is offline
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In the C41 process the cyan dye layer only achieves full coupling in the bleach that immediately follows the developer. Rebleaching may not provide the necessary conditions - try it! There is nothing to lose, because, as you write, the silver produced during development adds density to the image and makes it almost impossible to scan or print. Presoak before bleaching and fixing. Good luck.
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Old 7th June 2014, 06:00 PM
JOReynolds JOReynolds is offline
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Quote:
Originally Posted by Mike O'Pray View Post
...There's a school of thought that says bleach then fix in film processing aids longevity but it doesn't seem to be a universally held belief...
In the eighties I was invited to join a team to set up a dedicated system for processing 16mm Eastmancolor ENG film. The Kodak-Pathé team-member insisted on separate bleach and fix for image permanence. Pollution was then becoming an issue but the librarian, concerned with longevity over everything else, insisted on ferricyanide (yellow) bleach, even though there was a heavy environmental penalty compared with ferric EDTA (brown) bleach. Blix gets the thumbs-down for film but is specified for paper!
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Old 7th June 2014, 08:20 PM
Mike O'Pray Mike O'Pray is offline
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It is interesting that the situation you quote comes from Kodak. On another site it is the member who spent most of his working life at Kodak, working mainly on C41 film that also advocates separate bleach and fix in film processing but is happy with blix for RA4 and insists that blix for films is a second best solution

I cannot recall what if any practical evidence he quoted or showed to substantiate what I assume to be Kodak findings

While not wishing to play "devil's advocate" for the sake of it, I do occasionally wonder whether a prevailing philosophy in a company can influence things to the extent that another disinterested examination becomes a "not done" thing so eventually the position taken by that company becomes " the law"

Mike
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Old 8th June 2014, 08:23 AM
JOReynolds JOReynolds is offline
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Yes, Mike, I wonder if there has been any rigorous, unbiased research into longevity with different bleach procedures and formulae. Combined bleachfix was introduced for paper in 1970 with Ektaprint 3. There was a noticeable shift in colour balance when some colour negative films were treated first in C41 bleach instead of blix, presumably due to altered behaviour of the cyan layer. It didn't seem to make much difference to image quality, but I note that minilab film processors from Noritsu, Copal and others were configured for separate bleach and fix. This may have been to improve recycling of bleach and efficiency of silver recovery from fix.
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Old 8th June 2014, 05:26 PM
Mike O'Pray Mike O'Pray is offline
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I guess the problem of getting incontrovertible evidence is compounded by what I assume to be the improvement of C41 films as well

I still have some lab processed early to mid 1970s film and some, maybe all, the negs are beginning to shows signs of ageing. What I don't know is if the lab was using separate bleach and fix or blix.

What would be interesting is if Kodak processed the same two films, say 40 years ago. One in bleach and fix, the other in blix

By now some difference should be seen if there is a difference

Actually come to think of it, does the C41 process go back as far as the early 1970s?

Mike
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Old 8th June 2014, 06:56 PM
Lostlabours Lostlabours is offline
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Yes C41 came out in about 1972 or 3.

Colour films have much higher Silver content compared to Colour papers and it's very difficult to formulate a an economic Blix that will work consistently replenished.

Pip Pippard of Phototechnology managed to formulate an excellent Blix for films but other companies had problems.

If you leave a trace of silver in a colour film it shows as excessive grain, in a print it's barely detectable,

Ian
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