Why Does Presoaking Make a Difference?

[Bjorn Nilsson]

In a book written in the 80-ies by Lars Kjellberg (in the late 90-ies the author of the Photodo.se site) he did a series of tests on lots of film and he stated that:
Presoaking adds about 30 seconds to the development time, this because of the time it takes for the developer to replace the water in the emulsion, as Bruce W. pointed out.
It (probably) gives you a more even development, mainly due to the longer development time. (Also by the slower start, again pointed out by Bruce W.) This is an even more important factor when the dev. times are below 5 minutes.

//Björn

[Brian Ellis]

"Presoaking has little if anything to do with film sticking together"

Drop 5 0r 6 sheets of film as a pack into developer at the same time and see wht you get.

Why would I do that? The film would stick together. So I don't do that. I also don't drop my film on the floor, stomp on it with my working boots, and then turn on the light. In other words, I try to avoid doing things in the darkroom that would create problems when they can be easily avoided (in this case by plopping the four sheets in the developer one at a time).

[Brian Ellis]

Try to develop sheets where there are uniform areas(like a overcast skies) without presoaking and see what you get.
I think Bruce Watson hit it on the nail.

I don't know what I'd get since the skies in my negatives are usually fine and I don't presoak. What do you get?

Give me a break. If I was getting uneven skies in my negatives do you really think I'd just putter along using the same procedures time after time and never try to remedy the problem by any means at my disposal (including presoaking)? I don't presoak and I the skies in my photographs are fine.

Bruce's statement of the reason for presoaking is perfectly accurate (and is basically the same reason I gave in my original response). It's just that the problem he and I mentioned was applicable primarily to older thick emulsion films. It isn't normally a problem with today's films. But if you think it is, and if you like to presoak, by all means do so.

[sanking]

Bruce's statement of the reason for presoaking is perfectly accurate (and is basically the same reason I gave in my original response). It's just that the problem he and I mentioned was applicable primarily to older thick emulsion films. It isn't normally a problem with today's films. But if you think it is, and if you like to presoak, by all means do so.

Brian,

You develop in BTZS type tubes, right? How do you keep the film from sticking to the the side of the smooth walled tubes if you don't presoak? Whenever I have developed in tubes without a presoak the film sticks to the back because it does not wet out evenly.

Sandy

[Claude Sapp]

I use BTZS tubes, and Sandy is right, the film does have a tendency to stick to the tube after the development step. My solution is not pre-soaking, but to use a water tub as the stop bath and remove the developed film from the tube underwater, then transfer it to a fixer tray.

With regards to presoak, I do not use it with BTZS tubes, but can see how it might be of benefit to others that use tanks like Jobo or Unicolor to develop sheet film. It seems the presoak might slow things down as the tank is filled with developer, and allow the tank to fill up before the developer really affects the emulsion.

[cyrus]

Brian,

You develop in BTZS type tubes, right? How do you keep the film from sticking to the the side of the smooth walled tubes if you don't presoak? Whenever I have developed in tubes without a presoak the film sticks to the back because it does not wet out evenly.

Sandy

Hmmm....wonder why that is. Doesn't the emulsion face away from the tube sides? So what's sticky on the back of the film?

[Chris Strobel]

Doing 8x10 one sheet at a time in pmk, I see no difference pre-soaking or not

[Bruce Pollock]

Here's what St. Ansel has to say on the subject: "The pre-soaking allows the emulsion to swell and stabilize before it is immersed in the developer; this assures more uniform development." (The Negative, 1981).

[Brian Ellis]

Brian,

You develop in BTZS type tubes, right? How do you keep the film from sticking to the the side of the smooth walled tubes if you don't presoak? Whenever I have developed in tubes without a presoak the film sticks to the back because it does not wet out evenly.

Sandy

The film does stick to the back but I've never had any trouble getting it out either by putting pressure on the film with my right thumb and twisting slightly counter-clockwise while pushing the film up or by grasping the edge of the film and twisting counter-clockwise slightly while pushing up. Sorry if this isn't clear, neither of these methods is easy to describe, kind of like trying to describe the method used to tie one's shoes. But if you find it easier to remove the film from the tubes after presoaking that's certainly a good reason to presoak.

[Shen45]

A pre-soak in BTZS tubes is not required. Liquid contact with the antihalation backing has no impact on film quality for conventional processes. By their nature the tubes allow almost instant even application of developer to film by following Phil Davis' method of cocktail shaker agitation for about 5 - 10 second then snap spinning [log rolling] agitation for the duration.

Jorge described his method of removing the film from the tube on the BTZS.org forum as such. Keep the tube full of liquid and curl one corner of the film "gently" into the centre of the tube and at the same time apply "gentle" pressure as you remove the film.

Anti halation backing will often remain on the film when I carry out this step from the stop bath to the fix but the backing is removed fully within about 60 seconds in the fixer.
It is not essential for the developer to reach the back of the film. I use conventional developers such as D76, Rodinal and others as well as PMK in BTZS tubes and all films processes cleanly and evenly without any form of pre soak.

If you wish to go to the trouble of pre soaking film in the BTZS tubes and you are happy with your results then by all means do so, however there will be no difference. It is just adding extra time to the development run.