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  #1  
Old 9th September 2015, 10:07 AM
davidgc davidgc is offline
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Default Why pre-soak ?

After erring on asking this question, long before reading the recent C41 pre-soaking thread, I cannot help but ask 'why pre-soak ?'
Ilford do not recommend 'pre-rinsing' as part of their film processing guides due to uneven processing and Tetenal C41 do not mention it in their instructions.

A search has found very little information.

Thanks, David
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Old 9th September 2015, 12:38 PM
JOReynolds JOReynolds is offline
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Default The case for pre-soaking

In my experience of setting-up early Gretag and Copal printers, the easiest negatives to print were those that were correctly processed. Errors in temperature led to crossed curves, for which corrective filtration was ineffective - if the darker mid-tones looked right the highlights went green or blue, awful for skin tones. And if I got faces looking right, the shadows in the folds of wedding dresses looked weird.
Much of the equipment and many of the procedures used with 38°C processes were carried over from 24°C processes and this is where most of the errors occurred. So I carried a few calibrated and sheathed thermistors, about the size of matchsticks, which I taped next to the film. In processing machines the errors were usually due to partially blocked filters, leading to sluggish recirculation and temperature-layering. With three-gallon tanks in a water jacket, more than half a °C was knocked off when room-temperature replenisher was introduced, which took more than an hour to recover. But the greatest errors arose from plunging cold metal or plastic into the tank, or pouring warm developer into a cold plastic drum. Although I never encountered encouragement from chemistry suppliers, one or two pre-rinses of carefully-tempered water provided the necessary correction. The dilution of the developer usually needed an extra 15...20sec immersion to regain speed. But there was never evidence of crossed curves. And I had access to much more sophisticated measuring equipment than most enthusiasts.
So my recommendation is to get a good thermometer and pay attention to both pre-rinse and developer temperature. Do a 'dry run' with water (without film) in your usual equipment. One or two pre-rinses? Measure the temperature of the first pre-rinse as you pour it out of the tank or drum. If it's still a bit chilly, do it again. How long? A minute or so should allow effective heat transfer.
Happy C41 processing! And easier printing...
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Old 9th September 2015, 12:44 PM
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richardw richardw is offline
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Default

Quote:
Originally Posted by davidgc View Post
After erring on asking this question, long before reading the recent C41 pre-soaking thread, I cannot help but ask 'why pre-soak ?'
Ilford do not recommend 'pre-rinsing' as part of their film processing guides due to uneven processing and Tetenal C41 do not mention it in their instructions.

A search has found very little information.

Thanks, David
Pre-soaking for 5 minutes in water at the processing temperature gives you chance to remove all airbells before processing starts. I now pre-soak all black and white films in this way and development is now smooth with no airbells or streaks.

richard
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Old 10th September 2015, 08:31 AM
davidgc davidgc is offline
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So pre-soaking is to maintain temperature and to create a stable environment.
Tetenal does recommend heating the drum (tank in my case) before developing but keeping the airtight-ish tank upright in a washing up bowl is difficult!
I am surprised though Ilford do not emphasise this practice in their fact sheets.

Thanks.
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Old 10th September 2015, 03:26 PM
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it also gets rid of the anti halation coatings which are on a lot of mono 120 films
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Old 10th September 2015, 05:41 PM
davidgc davidgc is offline
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I was not aware of an anti-halation layer - is that the dye you can sometimes see washout with developer, particularly, noticeable with Foma film (a light green colour)?
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Old 10th September 2015, 07:29 PM
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Pre-soaking in my opinion is a complete waste of time and may even cause uneven development. The ingress of liquid into an emulsion is generally even. Once made, to ingress a second liquid requires displacement of the first which may not be uniform. I have never used a pre-soak and never intend to.
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Old 10th September 2015, 08:02 PM
alexmuir alexmuir is offline
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Default Why pre-soak ?

Quote:
Originally Posted by davidgc View Post
I was not aware of an anti-halation layer - is that the dye you can sometimes see washout with developer, particularly, noticeable with Foma film (a light green colour)?

Yes. The colours vary, and you don't find it on all films. If you do a pre-soak, the dye comes out at that stage (as monst has pointed out).
Alex
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Old 11th September 2015, 05:25 AM
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Domingo Domingo is offline
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Correct me if I'm wrong, but the anti-halation layer is in the opposite side of the acetate, isn’t it? so it should not affect the emulsion and its process.
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  #10  
Old 11th September 2015, 06:10 AM
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dsallen dsallen is offline
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The use of a pre-soak has been argued about by photographers for decades (and indeed often in this forum). There is a firm camp against and a firm camp for the use of a pre-soak.

Everyone argues from either the personal point of view ("I have always used a pre-soak" or "I have never used a pre-soak") or the theoretical point of view ("A pre-soak will/will not cause uneven development due to water ingress, blah, blah").

You will find that this thread will reflect these fixed positions.

In my case, I have always used a pre-soak whether that is for (now only) B&W or (when I worked commercially) C41 or E6. It is part of my routine and this has always been the case.

My main comment is that, whenever a colleague or student has approached me with a problem with uneven development (especially with 35mm films developed for short times as is the case with HC110 Dilution B, etc) we have introduced a pre-soak and that has cured the problem every single time. A subsequent comment is that, as someone who uses a reusable two-bath developer, a pre-soak also has the advantage of removing most of the dye so that Bath A does not quickly become a murky colour which is off-putting when developing your film (although this will not effect the developer's efficiency).

So, unless you encounter uneven development, it is a case of do what you always have done if it works for you. If you encounter any uneven development then, from my experience, introducing a pre-soak will solve this problem.

Bests,

David.
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