Effect of too long fixing?

[zerobuttons]

A general advice from several users here is that to establish a fixing time for a given film/fixer combination, one should process the film leader like the rest of the film, and then put it in the fixer and measure the time needed before the film leader clears. This time should be doubled for the rest of the film.

This indicates that one should just be sure that the film has been fixed for long enough.

My question now is: can there be any negative effect of fixing for too long?

 

[john neal]

Oh yes!

First thing to go would be highlight detail, but given long enough you could bleach away the whole image 😉

 

[jaap]

No as long as you keep reasonable times in mind that wouldn,t be a problem at all But why should one fix longer than two times the clearing time?

 

[zerobuttons]

.....But why should one fix longer than two times the clearing time?

I don´t think they should. I am actually thinking in the opposite direction: if even ever so small improvements in the quality of the negative were obtainable by reducing fixing time to the necessary minimum, it would be in the photographer´s interest to establish this time.
The answers here show me that going to that extent trying to establish a more precise measure for the exact point in time when fixing more doesn´t give any more effect, is a waste of time.

 

[russianRF]

Generally, you should fix two times the clearing time. This is a very long, well worn rule of thumb. If you fail to fix that long, you risk the long-term archival stability of your film. It could literally fog while in storage. I don't have personal experience with this, because I always properly fix my negatives. If you read most any in-depth discussion of the topic, they will indicate that failing to fix the negatives for twice the clearing time jeopardizes the long-term stability of the film. As far as I'm aware, fixing film "properly" doesn't jeopardize any detail in the negative at all.

This process is over a hundred years old. Kodak and others have been manufacturing chemistry similar to today's chemistry for the better part of a century. If someone truely has a new, break-through method, bully for them. But I seriously doubt you will gain any advantages in shortening your fixing time. Certainly, if you do, the onus will be on you to exhaustively document and *prove* the new process.

 

[Phantomas]

Hold on... "one should process the film leader like the rest of the film, and then put it in the fixer"...?
I just got into self-developing and was about to try this film leader test, but one detail that escaped me was that I need to process film leader? How do you get it out of the tank? Or do you develop the leader separately?
I just assumed I could try the leader-fix-test without developing... but of course I don't know any better 🙂

 

[Sam N]

Rookie question: what is the clearing time?

 

[russianRF]

Rookie question: what is the clearing time?

The time it takes to clear undeveloped film of visible emulsion; also, the time it takes to clear the undeveloped part of developed film. The two times are one and the same, hence being able to clip the leader tab off a film, and then being able to judge clearing time for the whole roll based upon twice the clearing time for that leader tab.

Clarification: "the undeveloped part of developed film" refers to the fact that, as light passes through a lens and strikes film, it produces an image. When you develop the exposed film, the image within the emulsion is reduced to elemental silver, which in turn forms the image that is NOT cleared away by normal fixing. Basically, the developer develops the exposed image on the negative, and the fixer clears away the remaining (relatively) unexposed portion of the emulsion. I have avoided saying "negative" or "positive" image specifically because the process is different for different kinds of film; in traditional black and white film, however, the exposed image formed by the lens+light is a negative image, and the remaining emulsion material around the negative image is what the fixer clears.

 

[David William White]

I think there's an optimum minimum time as given above, and one needs be careful about fixer exhaustion, as I've had a few sheets and rolls I've had to refix, but I'm not so sure about the detrimental effects of fixing too long. I don't think fixer will act as a bleach on the developed silver density, even if fixing goes on for days. I've left sheets in the fixer tray overnight and I don't think my negatives were any the worse for it. It's an easy test to perform, however.

Forthwith, I will make a contact print (constant time as per my process), then drop the neg into fixer for a couple of days, then make another contact print. I'll report back Friday night. I'll also drop a print in the fixer as well.

 

[dufffader]

HI Phantomas:
I'd snip off the film leader (a few cm is enough), and put the fixer into a little film canister (just a little will do. Then dip part of the film leader into the fixer and take note of the time that it takes for the film to be transparent. Once the test is done you can just pick the film out and rinse it before throwing it away. Fixing time = 2x time for it to be clear. No developing required for test.

Than again, I only do fixing test when I reuse fixers or if I suspect the fixer is close to expiry, just to be sure. If its new fixer solution, I skip the test.

Hold on... "one should process the film leader like the rest of the film, and then put it in the fixer"...?
I just got into self-developing and was about to try this film leader test, but one detail that escaped me was that I need to process film leader? How do you get it out of the tank? Or do you develop the leader separately?
I just assumed I could try the leader-fix-test without developing... but of course I don't know any better 🙂

 

[zerobuttons]

HI Phantomas:
I'd snip off the film leader (a few cm is enough), and put the fixer into a little film canister (just a little will do. Then dip part of the film leader into the fixer and take note of the time that it takes for the film to be transparent. Once the test is done you can just pick the film out and rinse it before throwing it away. Fixing time = 2x time for it to be clear. No developing required for test.

Than again, I only do fixing test when I reuse fixers or if I suspect the fixer is close to expiry, just to be sure. If its new fixer solution, I skip the test.

Thanks to phantomas for spotting my misunderstanding, and to duffader for explaining this in details.

Just one more clarification: you are doing the timing of fixer clearing in daylight, right?

 

[zerobuttons]

......
Forthwith, I will make a contact print (constant time as per my process), then drop the neg into fixer for a couple of days, then make another contact print. I'll report back Friday night. I'll also drop a print in the fixer as well.

Great. Thanks for taking the time to do this.

 

[Roger Hicks]

For more on fixing and the fixer test (with illustrations), see:

http://www.rogerandfrances.com/photoschool/ps how process 35-120.html

For over-fixing, the Ilford Party Line is that you might start to see a loss of highlight detail at 10x the clearing time, and even then, it's not certain. Go for 5x and it ain't a problem.

I normally use 2-3x.

 

[drewbarb]

John Neal is exactly right- fixing for too long could bleach detail out of your highlights, and indeed eventually all the silver might be removed from your film. But it would take a VERY LONG time. As a general rule, you shouldn't fix for longer than three times the clearing time (or rather, you don't need to); twice is sufficient. And just to clarify, you don't need processed film to test for clearing time- any bit of exposed film will do.

Tip: When you process 35mm film, you clip or tear off the leaders before you load the film onto reels, right? Instead of throwing them away, keep them somewhere dry so you always have something to test fix with. I have a small box in my darkroom full of them; since I started keeping them, I test my fix more regularly.

 

[le vrai rdu]

A general advice from several users here is that to establish a fixing time for a given film/fixer combination, one should process the film leader like the rest of the film, and then put it in the fixer and measure the time needed before the film leader clears. This time should be doubled for the rest of the film.

This indicates that one should just be sure that the film has been fixed for long enough.

My question now is: can there be any negative effect of fixing for too long?

too long fixing as noo effect, not enought fixing as effect 🙂

 

[russianRF]

According to Wikipedia, at least:

A disadvantage of the use of thiosulfate as a fixer is its ability to dissolve elemental silver at a very slow rate. If films or papers are inadequately washed after fixing, any residual fixer can slowly bleach or stain the photographic image.

However,

Over-washing can actually reduce the archival properties of film, as thiosulfate in very small concentrations has been shown to have a beneficial effect on film image stability.

 

[zerobuttons]

For more on fixing and the fixer test (with illustrations), see:
http://www.rogerandfrances.com/photoschool/ps how process 35-120.html
.....

Wonderful. Thank you.

 

[David William White]

Okay, I just pulled the sheet film from the fixer, and a paper print as well. That's three days in the fixer tray, the negative looks pretty good, and the print looks identical. I've hung the sheet to dry and will contact print and compare with my print of three days ago and report if there is any discernable change in the negative. I'll get to the final step tonight, but so far, I'm pretty confident.

 

[David William White]

3 Day Fix Test....

3 Day Fix Test....

Okay, to recap, earlier in this thread, some were wondering if their negatives were being harmed by fixing times running longer than the minimum necessary times, so instead of 8 minutes fixing time (my usual), I left a 4x5 negative as well as a print in fixer for 3 bloody days to see if anything would be left of them. I made a contact print of the negative before and after. Here is a single scan of the two contact sheets:

Ignore the dust. I think there is some minimal but still noticeable loss of density, but I'm not sure if it's within repeatable tolerances, slightly more exhausted paper developer, etc.

I think I need to dunk the negative and leave it for a lot longer (like a month) to see at least a one stop difference between contact prints to be sure.

The paper print that also spent three days in the fixer tray also seems just the same as when I first dunked it, but that's a subjective assessment.

I think that for all intents and purposes, there should be no practical discernable difference with fixing times running 10 times what your normal times are, and any loss of density comes after days.

So if you are worried, you can relax.

Full disclosure: Ilford Rapid Fixer, mixed up fresh about a week ago, contact sheets, 3 days apart, height locked, aperture locked, digitally controlled exposure time (my standard 90mm, f/8, 30 second contact print exposure). Film negative was underexposed by a stop, therefore expendible, and it was a little dustier the second time around (my sloppiness).

 

[zerobuttons]

.....
I think there is some minimal but still noticeable loss of density, but I'm not sure if it's within repeatable tolerances, slightly more exhausted paper developer, etc.
.....

Maybe I´m wrong, but I sense a difference in the windows in the background, to the right.
However, I think you have proved that fixing time differences counted in minutes should have no effect, as long as times are beyond the point where clearing of the film has been ensured.

Again, thank you for taking the time to do this.