Presoak: How long is long enough

Gerald;

ALL films contain wetting agents. They are necessary for the manufacturing process or they will not coat evenly. Once dried, these wetting agents or surfactants have little effect on the wetability of a coating such as in processing. That is why air bubbles can form with impunity on the surface of all films.

PE

That's interesting. I had been told that the wetting agents were there for machine processing.

Gerald, all coating formulas contain specific levels of surfactant (wetting agent) to allow coating. A multilayer color coating contains several carefully selected wetting agents at different levels in each layer to allow spreading and full separation of layers as they are put down all in one operation.

My formulas all contain wetting agents or they would not coat, and it is recommended that a wetting agent be used in many alternative processes when applied by brush or puddle pusher.

There are several threads in Alternative Photography which address the issue or ask questions about what agent to use or whether to use these wetting agents or how much to add etc..

PE

I guess we all have our different ways of processing. I know for me, with using a Jobo processor a presoak in important to bring the tank and film up to my standard 75* developing temp. I have also seen t-max sheet film developed without presoaking and you can read the density difference across the processed sheet of film. I guess it all goes down to what works best for you.

Oddly enough, I only presoak when using Ilford films. If I don't, the developer gets very foamy with my tap water and creates air bells during development. About 4 to 5 minutes of soaking is necessary. Yet there is no problem at all with Kodak, Fuji or Agfa films. I suppose there's something in Tokyo tap water that doesn't agree with English emulsions.

Another vote for 2 mins - but I only use it to bring the drum/film/reel up to temperature in the colder months. When the ambient temp is high enough I don't use a pre-soak, and haven't noticed any differences. As for the wetting agent in the film, once it's wet it's wet - isn't it? - does it matter if the pre-soak or the dev wets it?

Regards,
Neil.

About the length of time for me to mix up the working developer solution.

Bill

lee said:

I thought we were talking about
pre washing FILM instead of PAPER.
lee\c

Click to expand...

I pre-soak paper. Using minimal solution volumes for
developing one-shot the pre-soak puts the paper flat
on the bottom of a Cesco flat bottom tray. Developer
is used more dilute than usual for good mileage.
Same for the fixer. No stop needed.

Makes for one tray processing, dump one solution
and pour in the next. All in all very similar to rotory
processing using one-shot chemistry. Dan

I have one or two questions related to the original one:

1. Could the presoak be too long?

That is, I usually presoak my films for between 2 and 5minutes, starting the presoak while near the end of fixing the previous development batch (so while I am washing the films). But the other day I had to break in between the developments for outside the bath- (read dark-)room. So the films were in the presoak for longer (lets say 10-20minutes). No visible damage done, but I would like it to be confirmed by someone else too - is it possible to do damage to the film or the development process if the film is in the presoak for too long?

2. should I also presoak C-41 (and E-6) films before developing?

I have not developed E-6 by myself so far, so only gathering info. And I have not done a presoak on C-41, but feel it could be wrong. (I know it should be in the other section, but hell, it's highly related and could be useful to have the answer in one place).

Thanks for your answers

A wile ago there was a famous and awarded French chef who, when asked how much or how many, he answered "... juste assez...".
He used a lot of herbs for seasoning the sauce, but juste assez to have it plenty of taste...

Philippe

I pre-soak sheet film the lenght of one song on my Zune so I would say 3-5 min

One minute for me. (Cite Jason's aforementioned lack of patience.)

Never presoaked, never a problem

lightranger said:

If you don't do a proper presoak when processing film, you will get uneven development. Developer hitting dry film is a bad idea. It's important to let the presoak swell the emulsion of the film so it will evenly accept the developer. I use 5 minutes at the same temp. as the developer in my Jobo processor. With the t- grain films you will see the anti halation coating washing off when dumping the presoak, a dark green ugly color.

Click to expand...

Why is developer hitting dry film a problem? Why would a wet and presumably somewhat swollen emulsion permit a more evenly accepted developer? Wouldn't a presoak actually slow the rate of developer absorption because the water must exit before the developer gets int it? Do anti-halation coatings ruin anything other than one's sensibilities?

For divided developers, presoaking is definitely a no-no, filling the emulsion with water instead of precious developer. I realize that this thread is discussing ordinary developers.

I don't use a Jobo, just an ordinary tank and reel. Never had a problem that I could see.

Paul;

Fog a sheet of paper, and then put it into a developer and watch how even development is. (It is NOT by any means even, even with the best agitation)

Imagine, in film, that this is multiplied by 100X due to the higher silver load, higher gelatin and higher iodide!

This, the uneven development is not too important in paper because of the thnner emulsion and the fact that paper goes pretty much to completion. In film, none of this is true and so prewetting allows the developer to spread more quickly and more evenly across the film. Development is thus more uniform with less air bubbles.

PE

PE,
I don't doubt you for one milisecond. But it makes me curious why Ilford's instructions state that prewetting can cause uneven development.

On looking at it again, their no-presoak recommendation seems to be specific to rotary processing, though it's not explicitly stated.
http://www.ilfordphoto.com/Webfiles/2006216122447.pdf

Might it be because rotary processing typically uses a low volume of developer, so carry-over might over dilute the developer, or else locally dilute it?

Barry

bdial said:

PE,
I don't doubt you for one milisecond. But it makes me curious why Ilford's instructions state that prewetting can cause uneven development.

On looking at it again, their no-presoak recommendation seems to be specific to rotary processing, though it's not explicitly stated.
http://www.ilfordphoto.com/Webfiles/2006216122447.pdf

Might it be because rotary processing typically uses a low volume of developer, so carry-over might over dilute the developer, or else locally dilute it?

Barry

Click to expand...

I think you are probably right on. With color, you use more developer, but if you follow the Jobo recommendation or fill the tank completely, then there is no problem. But, some of the very dilute developers suffer from further dilution by the presoak.

I would say that normal developers with times under 20 minutes or so benefit from a presoak, but witl long development times using very dilute developers, a presoak will dilute the developer too much. I think that they are trying to cover all possible conditions.

Thanks Barry.

PE

It is interesting that in "The Rotary Processor Manual" produced in 1992 by John Tinsley he recommends a pre-rinse for all B&W films including Ilford to avoid uneven development. He does however warn against dilution below 1:1 for the very reasons just stated above. He says that the effect of a pre-rinse is to dilute the developer such that manufacturers' recommended inversion development time are good starting points so no need to reduce dev times as the Ilford site recommends. There is consistency here as Ilford times are without a pre-rinse and Tinsley's with. Tinsley explains why with his system of pre-rinse no reduction in dev time is required as above.

Reading bdial's reference to the Ilford site I now wonder if the reference to avoidance of a pre-rinse is specific to rotary processing and is not a general point about a no pre-rinse applicablility to all development. This would certain be consistent with the points placement at the end of the section on rotary processing.

It does however contradict Tinsley's experience who unequivocally recommends a pre-rinse with rotary processing.

Might make an interesting article in B&W Magazine if someone like Les McLean were to compare pre-rinse with no pre-rinse with inversion agitation: then with rotary processing and finally a comparision with rotary and inversion at dilutions higher than 1:1 such as some favour with the likes of Perceptol at 1:3.

pentaxuser

I think you would have to go to the higher dilutions to see anything.

PE

Neil Miller said:

...........As for the wetting agent in the film, once it's wet it's wet - isn't it? - does it matter if the pre-soak or the dev wets it?

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I'm sure it's correct that once it's wet it's wet, and wetting agent thereafter is not going to make any difference.

But if it's wet with developer which has contacted the film unevenly, then it will be wet but developed to some degree unevenly.

I started using presoak with 120 Neopan400 when I started getting some faint disks of slightly underdeveloped on the negs. (They didn't look like the airbells I got when I first started developing film 40 years ago.) I tried every kind of initial agitation, rapping, banging, shaking etc but the only thing that fixed the problem was presoaking (2 or 3 minutes). I still don't understand why I got the problem, but I do know what fixed it.

From my experience coating, a surfactant or wetting agent does not assist in wetting a dry film. If developer contacts film unevenly, the film is developed unevenly so a prewet is used to reduce this problem.

Along with that, the prewet reduces air bubbles which cause pinhole type defects.

PE