Why Does Presoaking Make a Difference?

[Kevin Crisp]

I know that a presoak for short development times is recommended often. But I don't understand why it makes a difference so I thought I'd ask. Here's my thinking on it:

Let's take tray development to make it easy. Let's suppose for some reason you measure your temperatures and do the math and come up with a development time of 3 1/2 minutes -- well in the range for which most people recommend a pre-soak. I know from watching the process in the light that if I put a sheet of 4X5 or 5X7 film in a tray that the entire surface area of the sheet of film will be under the solution in one second or less. Often, a lot less. Since the emulsion is essentially uniform in composition, it seems to me that it should all be moving toward the 3 1/2 minute "done" mark at the same pace, plus or minus one second or less. As a percentage of difference the non-uniformity of development time should be insignificant. (Less than the time difference between sheets that results from the few seconds delay in putting the second sheet in the solution, for example, if using a slosher, or much less than the delay into the stop and the fixer is shuffling multiple sheets.)

So why would soaking the film in water first make development any more uniform? It isn't like the emulsion surface is water resistant. Emulsions soak up water in a flash. I can see that if you are naturally inclined to not get the film under the developer promptly (for example, dropping it in the tray and letting it float around for 30 seconds before really pushing it under) that could lead to nonuniform development, but in normal processing, why does a presoak do anything more than add a handling step and a chance for scratching film when it goes in the developer?

[cyrus]

I just presoak rollfilm to help prevent air bubbles. Never heard of presoaking used to change development time.

[Alan Rabe]

I don't know that it does much for tank development where the film never touches itself other than just preparing the emulsion for a liquid. But for tray development it means having seperate sheets of film as opposed to a block of plastic when you put it into a liquid. Each sheet must be presoaked for 15 to 20 seconds in water, when all sheets have been presoaked you can then move them in mass to the developer. If you don't do this the sheets will stick to each other like glue and you cannot seperate them without destroying the emulsion.

[Brian Sims]

Now I know why I never develop film in trays....some of these descriptions could be material for a darkroom horror movie. I think the best way to process film is never...never let one piece of film touch another. Period.

[Kevin Crisp]

I can understand the no-stick theory, and I accept that if you are using that technique, but pre-soak is often recommended for even development and that is the part I do not understand.

[Ken Lee]

Perhaps they are using the term in its most general meaning. Being able to place the film in the developer all at once, and thus avoid sticking, promotes even development, "as it were".

[Brian Ellis]

Presoaking has little if anything to do with film sticking together. The purpose of presoaking is to allow the emulsion to expand or swell and stabilize, which in turn is supposed to promote even development. It used to be a big deal with the old thick emulsion films but I don't think it serves much purpose with today's films. IIRC some manufacturers, e.g. Ilford I believe, specifically recommend against it.

The only time I presoaked was when I was experimenting with PMK and I did it then because Dan Burkholer's book recommended it. However, after a few months I decided to try PMK without the presoak and everything seemed fine so I stopped doing it even with PMK. So IMHO the principal effect of presoaking is to add an unnecessary step to the development process and thereby increase the length of time for which you're standing in your darkroom inhaling chemical fumes.

[Andrew O'Neill]

I presoak film because it makes it's easier to slip it into a film tube.

[Alan Rabe]

"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.

[David A. Goldfarb]

I don't see why anyone would put several sheets into the developer at once in a stack. Some films/developer combinations do better with a presoak, but for those that don't require a presoak, the sheets can go into the developer one at a time, and they won't stick together.

[Bruce Watson]

I know that a presoak for short development times is recommended often. But I don't understand why it makes a difference so I thought I'd ask.

Here's a thought. No guarantees on the correctness of this, but I've read it somewhere at some time over the last few years. IOW, you might want to research this out further to see if it applies to your specific situation.

The thought is that water and water-based solutions permeate the dry emulsion fairly quickly (20 seconds? 30?). If the solution you use is your developer, it is sucked into the emulsion and starts working very quickly.

If however you used a water presoak, the developer gets into the emulsion by diffusion. That is, it has to displace the water that is already there before it can get in and start acting on the latent image. This is a slower and more gentle reaction. It could easily add another 30-60 seconds to your development time, depending on your agitation technique. The more active your agitation, the less time it takes for the developer to displace the water and therefore the sooner active development starts. Temperature effects the diffusion process too.

This may be why some advise a water presoak when short development times are indicated.

[Gene McCluney]

, the sheets can go into the developer one at a time, and they won't stick together.

Yes, if you wait 15 to 20 seconds between sheets. Too long for even development of all sheets. The presoak swells the gelatin and renders it slick and non-sticky, therefore when you transfer the sheets to the developer one by one, you can do it just as fast as you can lift and transfer each sheet. Of course in putting sheets into the water presoak, you should pause a bit between placing sheets, so each sheet can become fully wet before the next one is placed on top of it...but it is water, so no activity will take place.

[Jim Jones]

I found a presoak absolutely necessary when solarizing Tech Pan film in Solarol developer. Perhaps reducing exposure and extending development time would have eliminated the need for a presoak, but once I could get predictable results, any change would have wasted time and material.

[domenico Foschi]

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.

[Marko]

My guess would be that it is all about surface tension.

Sufrace tension is, quite simply, a propensity of a liquid toward forming drops, beads and curved surface in general. It is caused by various inter-molecular bonds which pull individual moleculs inward. Surface tension is charateristic for each liquid, but also depends on the nature of the bordering surface.

Since a developer is always a water-based solution there is no surface tension between it and water, therefore soaking the emulsion in water prior to imersing it in developer serves the purpose of breaking the surface tension and pulling the developer into the emulsion faster and more uniformly.

[John Kasaian]

I presoak Tmax 4oo sheets to get the purple stuff out.

[Mattg]

I started using a pre soak with Ilford roll films, against the manufacturers recommendation, to alleviate some problems with uneven development. It works very well for me, no more streaks. I did learn the hard way not to agitate during the presoak because I'd get lovely foamy bubbles that stuck to the film during the first phase of development.

[Sandeha]

Jobo tanks for roll film specifically recommend pre-soaking (irrespective of film brand) and I assume it's for the diffusion reason explained above in conjunction with dev flow issues around the spool edges.

It does affect dev time, but more importantly pre-soaking prevents splotching and streaks. Never had a streak since I began pre-soaking.

[David A. Goldfarb]

Yes, if you wait 15 to 20 seconds between sheets. Too long for even development of all sheets.

It probably depends on the developer and film, but I find that a few seconds per sheet is sufficient (usually using ABC pyro) to get it into the tray and pat it down before adding the next sheet.

[Jim Jones]

. . . I did learn the hard way not to agitate during the presoak because I'd get lovely foamy bubbles that stuck to the film during the first phase of development.

Too high a concentration of wetting agent may aggrevate the foaming.

[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.

[sanking]

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.

If I do not presoak the film it will sometimes stick to the back with such force that I wind up having to apply a lot of force to remove it, and I have even scratched a sheet or two of film this way.

The presoak does not take me any extra time. I have a special tray of water where I place the tubes. When I am ready to start a developing session I just turn off the lights, open the film boxes and transfer the 6-8 sheets I plan to develop to the tray where the tubes are located, and then load the film into the tubes. By the time I finish loading the film in the tubes the presoak is over and I continue with development.

Sandy King

[Shen45]

Hi Sandy,

I agree a presoak it is a personal choice. I never have so I don't but I did initially have a problem getting film out of the tubes but only because I was trying to remove the film without the tube full of liquid. I too have had the misgivings associated with the feeling that the film is goinfg to be damaged but I've put nearly 500 sheets through my tubes and have not had any hassles since following the advice Jorge gave about having the tube full of liquid when removing the film.

I remove my sheets from the full tubes after the Stopbath and place them in 5x4 Kodak SS hangers in the fixer.

I have also found that a developer with a higher Sodium Sulphite content [D76] seems to leave less backing and often the film doesn't stick to the tube.

I'm not sure if this is correct and you may know Sandy but with UV processes the removal of the backing [perhaps a water bath] in the BTZS tubes is more important than in a conventional silver process. As I only do silver work I cannot offer actual data on this.

Steve

[domenico Foschi]

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.

Brian, I wasn't referring to your post.
I regret you took it personally.
I develop in trays and if I don't presoak, uniforms areas tend to have those blotches typical of uneven development.
This is all the break I can give you.:)

[Brian Ellis]

Brian, I wasn't referring to your post.
I regret you took it personally.
I develop in trays and if I don't presoak, uniforms areas tend to have those blotches typical of uneven development.
This is all the break I can give you.:)

Domenico - That's good enough, I'll take all the breaks I can get. : - )

[Armin Seeholzer]

Hi
I do a presoak to get more even development on my tank processing with Kodak hangers!
I get more even develoment since I do it with a presoak of 1 min in water!
But still not fully happy because still get on critical parts sometimes a bit of unevenness! With the kodak hangers but almost only the last 3-5 mm outside around!
Armin

[MIke Sherck]

An interesting facet of presoaking is the colors you get in the water. TMX is an intense blue. Foma 200 is an absolutely gorgeous emerald green. Anyone get red or yellow?

Mike

[IanMazursky]

Neopan gives a black soup and the Aerial dupe film that ive used gives a nice yellow.

I have also found the need to use a pre soak. I use a PhotoTherm rotary tube. Without it the air bells in the 4x5 tube are a real problem. It doesn't matter what film I use, I always need a pre soak.

[neil poulsen]

The Ilford Tech with whom I spoke said that their film has enough wetting agent to make pre-soaking unnecessary.

Reading this thread, I'm thinking that the wetting agent reduces the surface tension of the water, thereby reducing the developer's tendency to bead.

[MIke Sherck]

I pre-soak for two reasons: prevention of film sticking together in the developer (sorry, Brian: my film sticks extraordinarily well without pre-soaking, not at all after a short soak,) and to get the anti-halation dye off. For Foma 200 8x10, the dye is an absolutely lovely emerald green. I pre-soak for 2 minutes, more or less, with a couple of passes through the stack during the soak, mostly to get all the dye off. My developing time is 5 minutes in straight D-76 at 68 deg. (F) and I process four sheets at a time in a quart of D-76, which I treat as the developer's capacity. All this is in 8x10 trays.

Mike

[Ed Richards]

I use the jobo expert drums for 4x5, on a bessler base, filling by hand. I did not presoak for a few hundred sheets when I started. I noticed occasional negatives with a streak in the sky that looked exactly the way water would run down a negative if you poured a stream onto one, and the the correct direction for that to happen when filling the drum. Started pre-soaking and this went away completely. I have noticed no effect on development time, but with Tmax the emulsion is so thin that I discount any swelling effects. Then started wearing gloves when I loaded film and my greasy finger prints also went away, finally leaving me perfect skies.:-)

[Brad Rippe]

I presoak in trays for two reasons, even development, and, I find when adding several sheets of film to a tray, it takes many seconds to place them all in,
especially if the film is sticking together a bit (not from liquid, but from the propensity of film to stick to another film).

If I'm putting film in developer directly, this process could take from 30 seconds to a minute. With a presoak, I take the entire stack of film, maybe 6-8 sheets, and move them all into the developer at once. That way they all get the same time in the developer.
-Brad

[Gene McCluney]

Hi
I do a presoak to get more even development on my tank processing with Kodak hangers!
I get more even develoment since I do it with a presoak of 1 min in water!
But still not fully happy because still get on critical parts sometimes a bit of unevenness! With the kodak hangers but almost only the last 3-5 mm outside around!
Armin

Try going for a longer pre-soak, say 4 minutes with agitation at 30 sec. intervals. Some film is just more prone to streaks when developing in deep tanks. The longer pre-soak seems to help me.

[Philippe Debeerst]

It occurs to me that B&W film is more prone to problems when NO presoak is applied than colour film (pos. or neg.), I do not know why but I do not really care.
I once, unwillingly, pre soaked APX 400 for a half a day, there was no problem at all, I just added 1 min to the dev. time (Rodinal 1+50, 12 min, 20°C). Every time I did not presoak, 35 mm- , roll film or sheets, the streaks and bubbles stroked again! So, regardless the brand of film, chemicals or tank/try, I do presoak for the time needed to prepare the developers working solution. And, unless I am convinced with good argumentation, to which I am always open, I do not feel the urge to change that.
BTW, what are BTZS tubes, I Googled for it but did not find the manufacturers website nor a good information pamphlet. I am using Jobo drums and open trays...

Thank you,
Philippe

[Tim Curry]

I presoak because I'm doing more semi-stand development now and want to have the most even development possible. With a presoak, as I'm mixing developer, then a full minute of initial agitation, there aren't any problems with uneven skies. I just figure its cheap insurance. tim

[evan clarke]

It's really easy to try and then make your own conclusions. I use a Jobo most of the time and presoak for Pyrocat and other slow developers. I don't for Xtol, FX37 and other Sexton recommended 5 minutes presoak for everything to promote even development..Evan Clarke

[Shen45]

BTW, what are BTZS tubes, I Googled for it but did not find the manufacturers website nor a good information pamphlet. I am using Jobo drums and open trays...

Thank you,
Philippe

Try

www.btzs.org

or

www.viewcamerastore.com

[scott_6029]

It's to prevent uneven development in trays for me.

[Philippe Debeerst]

Thank you Steve