Fixing Overnight

I saved the clear leader from the last 35mm film I developed (HP5+). I put half of it in fresh fixer, forgot about it, and it soaked overnight. The re-fixed side is noticeably clearer than the unfixed side. That said, the film didn't look particularly unfixed to begin with -- this is just a routine test I do.

So I repeated the test using a more reasonable time of 15 minutes, and the re-fixed side is no clearer.

What's going on here? I would expect 15 minutes in freshly mixed fixer (Ilford Rapid Fixer 1+4) to be sufficient.

Leaving film in a fixing bath particularly a rapid fixer can cause bleaching of the images. However this takes more than 15 minutes. Film should be completely fixes long before 15 minutes

I think you are saying that you developed and fixed a roll of film. You then cut off the clear part of the leader immediately before the developed frames and then dipped half of this clear leader in fix again overnight. The re-fixed( second fix) half after many hours overnight looked no different from the once fixed leader whereas it is normally clearer? A third fix of 15 mins made no difference to things.

If the leader was fully developed and fixed when the whole roll was developed and fixed fully, I am unclear why a second overnight fix would make any difference. The leader is already fully fixed. isn't it? However I have never tried this so cannot speak from experience. It may be that my confusion arises from misunderstanding what you actually did.

pentaxuser

Indulge me.

It looks to me like there was some base fog (which there always is--that's not a defect) and the fixing overnight bleached that back to the clear plastic, removing the base fog.

Thanks for the diagram but I am still confused. The darker part on the right as we look at the leader, looks to be that first part of a film leader which is exposed to light when you load the film into the camera. Isn't this part zapped ( a good "Superman" comic word) with light so on developing and fixing goes black. The part on the left is that section which doesn't see any light but is wound on to the camera beyond the section that contains the exposed frames.

Both the light and the dark sections of the leader are meant to be fully developed and fixed in the processing stages. If they are, then is it not the case that that neither the light nor dark sections can be visibly affected further with more fixing but see my qualifications of this statement below?

If my understanding of the chemical process is correct then it suggests that the clear section may not have been fullyfixed during processing and a second fix ( the overnight fix) fully fixed it so that it showed as clearer. The dark exposed leader section was also not fully fixed during processing but being exposed and thus dark, full fixing might not show up a detectable difference?

If I am right then it may suggest that the whole film wasn't fully fixed so the exposed and processed frames are not fully fixed,. Whether this will matter in the long run might be a function of how close to fully and correctly fixed the film was during normal processing. If the fixer was fresh and the fixing time in processing was correct, then it might simply be that the "much clearer" leader post overnight fixing is a clear leader that has now been seriously over-fixed by several hours so more fixing of the exposed frames of the film is not beneficial and might be detrimental but of course your question may not be directed at whether the film was correctly fixed. I have never seen the effect of fixing for several hours on a film but clearly from everything I have heard, it can be over fixed.

Have I now understood what you did correctly and if so, do my conclusions make sense?

Thanks

pentaxuser

It may be antihalation dyes that are being washed out overnight. Sometimes a regular fix doesnt get it all, though it doesnt hurt the image for the most part.

It would be interesting to conduct another experiment. Soak part of another film in water overnight. Then you would know if it is an effect of fixer or just the removal of any remaining sensitising dye.

I'm simple. I just double the clearing time for total time in the fixer. I read about it in a book by David Vestal. I've been doing this for decades and it works.

pentaxuser said:

Have I now understood what you did correctly and if so, do my conclusions make sense?

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Makes sense, but the diagram with the cut leader drawn out was just meant to show that I was working with the film leader. I cut off the fully exposed portion for this test, so I was only ever working with clear (unexposed) film. Sorry for the confusion.

Svenedin said:

It would be interesting to conduct another experiment. Soak part of another film in water overnight. Then you would know if it is an effect of fixer or just the removal of any remaining sensitising dye.

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I'm going to try this...

Mainecoonmaniac said:

I'm simple. I just double the clearing time for total time in the fixer. I read about it in a book by David Vestal. I've been doing this for decades and it works.

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This what I don't like about the traditional clearing test -- that you start with the assumption that whatever working solution fixer you're using is capable of fully clearing the film. If the fixer is unable to do that, then the test just tells you how long it takes your fixer to do the most it can do. I keep a small sample of fresh fixer that I use just for these tests.

I should add that the original fixer used (to process the film) was mixed in November and fixed about a half dozen films before this one. I wouldn't expect it to be anywhere near capacity.

glbeas said:

It may be antihalation dyes that are being washed out overnight. Sometimes a regular fix doesnt get it all, though it doesnt hurt the image for the most part.

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It's most likely that the antihalation dye in the film base is being 'soaked out' by the long immersion in your fixer overnight.

A second, and probably less likely cause might be fog produced by physical development due to light exposure since it's the portion of the leader that is always outside the canister that is the portion that is slightly darker.

Neither case is anything to worry about.

mdarnton said:

It looks to me like there was some base fog (which there always is--that's not a defect) and the fixing overnight bleached that back to the clear plastic, removing the base fog.

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Haven't any of you taken an out of date B&W film and run it through fixer to get clear film?. I don't remember any base fog still in the film after ten minutes in thiosulfate fixer plus wash. Remember 35mm has the most base fog and might take longer. I don't think even fresh thiosulfate would bleach base fog in ten minutes and would be surprised if leaving it in that fixer all night would do it. My point is this is one of those things we can find out in our own darkrooms. using thiosulfate fixer, not quick-fix............Regards!

bvy,
First, your fixer is likely working just fine; fully-fixed film has a lot of other stuff in it, most of which is supposed to be there, that keeps the film from being completely clear.

Fixing way too long (e.g., overnight) could:
1. Bleach out the base fog on the film. Every developed film has some base fog. It is a normal result. This makes the clear portions of film a bit denser than the clear plastic base would be, but that's how the system works; it's supposed to be there. If you had fixed a negative with an image that long, the image would be bleached as well.
2. Remove other components in the emulsion. There are some sensitizing dyes, etc. that often are still in the emulsion in residual amounts even after proper processing. While not altogether desirable, these are also accepted in fully-processed film because more fixing or other treatments needed to remove the dyes would adversely affect the image. So, they are kind of supposed to be there too.
3. Remove the emulsion entirely. The gelatin emulsion on the film itself can be removed through extended wet time. The gelatin swells and separates from the film base. If this happens, then the remaining acetate film base is very, very transparent in comparison to the film with the emulsion on it. The emulsion is definitely supposed to be there

Any of the above could explain what you are seeing. However, whatever the reason, it is not underfixing that causes this. Don't blame the fixer or the time-tested and accepted tests for proper fixing time.

If, however, you suspect that your fixer may not be doing the job, test it against freshly-mixed unused fixer to see if it clears as well as the new fixer.

Best,

Doremus

Thanks everyone.

One further observation -- Delta 400 seems to have a lot of base fog. I've developed three rolls now (all 120). Also it has a bluish tint. I developed a roll of Acros tonight, fixed in the same fixer, and the film base is clear as glass. The Delta 400 was developed in Perceptol 1+1 and the Acros in XTOL 1+1, but I wouldn't expect that to have an effect on how it clears.

Also the base fog will be "set" on a fully developed roll of film, while an undeveloped roll of film, the fog has not been developed or "set" so the fixer has an easier job of bleaching it out.

bvy said:

Makes sense, but the diagram with the cut leader drawn out was just meant to show that I was working with the film leader. I cut off the fully exposed portion for this test, so I was only ever working with clear (unexposed) film. Sorry for the confusion.


I'm going to try this...


This what I don't like about the traditional clearing test -- that you start with the assumption that whatever working solution fixer you're using is capable of fully clearing the film. If the fixer is unable to do that, then the test just tells you how long it takes your fixer to do the most it can do. I keep a small sample of fresh fixer that I use just for these tests.

I should add that the original fixer used (to process the film) was mixed in November and fixed about a half dozen films before this one. I wouldn't expect it to be anywhere near capacity.

Click to expand...

bvy said:

Makes sense, but the diagram with the cut leader drawn out was just meant to show that I was working with the film leader. I cut off the fully exposed portion for this test, so I was only ever working with clear (unexposed) film. Sorry for the confusion.


I'm going to try this...


This what I don't like about the traditional clearing test -- that you start with the assumption that whatever working solution fixer you're using is capable of fully clearing the film. If the fixer is unable to do that, then the test just tells you how long it takes your fixer to do the most it can do. I keep a small sample of fresh fixer that I use just for these tests.

I should add that the original fixer used (to process the film) was mixed in November and fixed about a half dozen films before this one. I wouldn't expect it to be anywhere near capacity.

Click to expand...

The double the clearing time method works. It indicates how fresh the fix is. Also, if the clearing time is excessive, this will tell you to replace the fix. The whole point of fixer is to remove any unexposed silver salts, not to necessarily make the film base "clear". Some film bases are clearer than others.

Mainecoonmaniac said:

The double the clearing time method works. It indicates how fresh the fix is. Also, if the clearing time is excessive, this will tell you to replace the fix. The whole point of fixer is to remove any unexposed silver salts, not to necessarily make the film base "clear". Some film bases are clearer than others.

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Can you summarize the steps that you're using or link me to a resource? I've know there are variations...

bvy said:

Can you summarize the steps that you're using or link me to a resource? I've know there are variations...

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I could only speak for myself about the proper way of fixing film. After dumping the stop bath. Pour your fixer in the tank and start the timer. Put the cap back on the tank. agitate for at least a minute. Don't get tempted to open your tank before one minute because this may fog your film. After a minute, open your tank and look at your film. If your film doesn't look milky and the film is cleared, agitate in the fixer for another minute. If it's milky, agitate until your film is cleared. Look at the timer to see how much time has lapsed. If it took 2 minutes for your film to clear, agitate for another 2 minutes. It's that simple. Again, your fix time is 2x the time it takes to clear.

bvy said:

Can you summarize the steps that you're using or link me to a resource? I've know there are variations...

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My "How To" article on this: https://www.photrio.com/forum/resou...ixing-procedure-for-black-white-negatives.75/

MattKing said:

My "How To" article on this: https://www.photrio.com/forum/resou...ixing-procedure-for-black-white-negatives.75/

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That's more or less how I would I have described the test. My problem with it is that it assumes the fixer being tested is capable of fully clearing the film. If it's exhausted, then that first drop you put on the film will not fully clear the film, and the test tells you how long the fixer is capable of doing the most it can do.

Rereading what you have, I don't think we disagree. You do call it a "test for clearing time" which is accurate. I think some people mistakenly think of it as a test for fixer efficacy.

bvy said:

That's more or less how I would I have described the test. My problem with it is that it assumes the fixer being tested is capable of fully clearing the film. If it's exhausted, then that first drop you put on the film will not fully clear the film, and the test tells you how long the fixer is capable of doing the most it can do.

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Actually, the visual test will reveal whether or not the film has been cleared.
If it isn't cleared, it is at least partially opaque, and there will be at least some areas that you cannot see through.. If it is cleared, you can see through it.
A colour tinge or base fog don't block you from seeing through the film, and are evidence of something other than incomplete fixing.

MattKing said:

Actually, the visual test will reveal whether or not the film has been cleared.
If it isn't cleared, it is at least partially opaque, and there will be at least some areas that you cannot see through.. If it is cleared, you can see through it.
A colour tinge or base fog don't block you from seeing through the film, and are evidence of something other than incomplete fixing.

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There's a lot of wiggle room between clear and partially opaque. Film I assumed was clear was suddenly not so clear when I processed some later film in fresh fixer. And there's nothing more painful than refixing cut film.

Now when I prepare fresh fixer, I make a little more than I need and fill a 60ml bottle to capacity with this fresh fixer. This sample is used ONLY for tests. My routine test is to take a clear piece of the last film that I processed (from an unexposed 35mm leader, or either end of 120 that gets clipped off). I place half of the clip in this fresh fixer and leave it for 15 minutes. Pull it, rinse, and dry. The refixed portion should be no clearer if my fixer is doing its job. If there is a difference, then I need to either fix for longer or prepare new. Granted this isn't exactly a proactive test, but usually I can detect very subtle changes that give me a heads up that my fixer is starting to fail. I also do the clearing test that you described, but I start with a drop of fresh fixer from my sample and clear the remainder in my working solution fixer.

Let me ask a question in regards to film processing. Is there a difference between "Clear" and "Cleared" as cleared of unexposed silver? There are some film bases that aren't clear after processing. Milky is definitely bad.

When I used "partially opaque" I was using it to refer to "opaque in some sections, and not opaque (clear) in others".

MattKing said:

When I used "partially opaque" I was using it to refer to "opaque in some sections, and not opaque (clear) in others".

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Got it. That would be a more obvious sign of a problem.