I need a long lasting fixer solution.

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pentaxuser

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Fixing too short is always worse, because this may leave poorly soluble Silver Thiosulfate salts in the emulsion, which will not wash out.
This is not an attempt to contradict your statement but I was surprised at how little fixing time appears to be needed according to this video by John Finch. The relevant section is from 4 mins 15 secs



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Radost

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Be careful with C41RA fixer, it is very powerful and extremely fast. I check it recently, a test strip of Foma 400 in the normal C41 working solution was totally clear in 10-15 seconds at room temperature. The risk of overfixing and other potential problems with B/W films could be in the range of just one minute more than neccesary. I used 60 seconds with Foma 400 and film looked ok to me.

Makes sense since it has to fix 3 times the amount of black and white. This is why I guess in needs 3 to 1 dilution.
 

koraks

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Makes sense since it has to fix 3 times the amount of black and white.

In fact, no. The silver content in C41 film is far less than in B&W film:
* B&W film needs to be able to build more density than color film.
* In color film, the density is produced by the dyes, not the silver, and it so happens that relatively little is needed to create sufficient dye density.
This of course doesn't say all that much about things like fixing speed and fixer capacity, which are dictated by other things in addition to actual silver content. But from a fixing point of view, a color film isn't all that different from a modern tabular grain film (in fact, that's what it is, at least the B&W side of it).
 

foc

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I have never heard of over fixing with B&W films before. I mistakenly over fix 2 B&W films (my own and not a customer's) a few years ago.

I was developing my own 2 films at the end of the day, in my minilab, and as the fixer timer alarmed, I got called away and I intended to get back and wash and dry the films.

Of course, I forgot, (after a long day) and only discovered my mistake the next morning when I opened up the shop.

The 2 films had been in the 600mls (1+4) of Ilford Rapid Fixer for just over 12 hours.

I poured out the fix and proceeded to wash the film and then inspect the damage.

To my surprise, the negatives look ok. Later when I scanned and printed them they look ok too.

That was my experience for what it's worth.
 

Donald Qualls

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To my surprise, the negatives look ok.

If that had been microfilm, your results might well have been different -- but this usually won't cause trouble with conventional or tabular B&W films.
 

MattKing

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12 hours would do a really good job of saturating the gelatin in the film emulsion with fixer - extending the wash time would have been in order. Best to check it with the appropriate test.
But the amount of bleaching probably wouldn't yet be large.
 
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Has anyone done any testing or does anyone know of literature that quantifies the effects of overfixing? Just how long do you have to fix black-and-white film in rapid fixers before image degradation becomes an issue? I tend to think that you'd need to leave the film in the fixer for an inordinate amount of time before shadow details showed significant bleaching.

Underfixing or using fixer beyond its capacity, on the other hand, presents a real danger. Trying to keep fixing times for film to a minimum is risky, IM-HO. I like to fix film for 4x the clearing time in fresh fix, which gives me the 2x time for fixer at its exhaustion point, and then make sure I discard the fix long before the film clearing time reaches double that in fresh fix. I'm fairly certain that I'm not overfixing.

Now fiber-base paper - that's another issue. Keeping fixing times as short as practical and making sure wash times are sufficient for the amount of time the print has been fixed (as well as using a wash aid correctly) are best practice here.
Film doesn't absorb fixer into the base, so fixing longer is much, much less of an issue.

Doremus
 

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How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?
 

koraks

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How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?

I could think of some tests. But I personally wouldn't bother conducting them; I'd rather spend my time making prints. For some reason I've been able to navigate between the Scylla and Charybdis of under- and overfixing. Threads like these sometimes make it seem like a miracle if someone pulls it off, but it turns out it isn't all that complicated!
 

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How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?

I once left a B&W print in Agfa 304 fixer (which is very acidic, pH slightly above 4) for about 2 hours (stepped out of the dark room and forgot). The paper curled up, which caused the center part of the print to stick out of the fixer bath. Result: center part looked normal, left and right hand side of print looked seriously bleached.

There are some reasons, why few people ever notice over fixation and bleaching:
  1. It typically happens uniformly and is therefore much less noticeable than my dark room blunder.
  2. It doesn't happen with neutral or alkaline fixers, even after hours. BTDT.
  3. We study prints in wet state, but prints tend to get darker when they dry (dry down effect), so in many cases uniform bleaching through fixer is a welcome effect.
  4. Many here love fat negatives (yes, I plead guilty), which can also only benefit from bleaching in the fixer.
 

faberryman

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I once left a B&W print in Agfa 304 fixer (which is very acidic, pH slightly above 4) for about 2 hours (stepped out of the dark room and forgot). The paper curled up, which caused the center part of the print to stick out of the fixer bath. Result: center part looked normal, left and right hand side of print looked seriously bleached.

There are some reasons, why few people ever notice over fixation and bleaching:
  1. It typically happens uniformly and is therefore much less noticeable than my dark room blunder.
  2. It doesn't happen with neutral or alkaline fixers, even after hours. BTDT.
  3. We study prints in wet state, but prints tend to get darker when they dry (dry down effect), so in many cases uniform bleaching through fixer is a welcome effect.
  4. Many here love fat negatives (yes, I plead guilty), which can also only benefit from bleaching in the fixer.

How long does a print have to remain in the fixer before bleaching occurs?

Just as an example, looking at the Kodak Rapid Fixer datasheet, for resin coated papers, the recommended time for the single bath method is 2 minutes, or for the two bath method, 1 min in each bath. For fiber based papers, the recommended time for the single bath method is 10 minutes, and for the two bath method, 2:30-5 minutes in each bath. Kodak explicitly states not to fix for longer times. I use Ilford Ilfofix, also a rapid fixer, and the times are considerably less. Will fixing for the recommended times for the particular fixer you are using result in bleaching? Are people fixing for longer than the recommended times, and if so why? Granted, if you leave your print in the fixer for two hours, or overnight, it should not be surprising to find that you overfixed it.
 
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Rudeofus

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There is no standard process for "bleaching B&W paper in fixer". Bleaching speed strongly depends on fixer pH (which can in turn change with stop bath carryover - or developer carryover) and fixer strength/exhaustion. If you are unsure, take a fixed print and dip it halfway into your test fixer. Take note, when visible bleaching has occurred and fix your prints for less than that.
 

MattKing

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Many here love fat negatives (yes, I plead guilty), which can also only benefit from bleaching in the fixer.

Let me join you in that particular corner of shame.
Whereas my preferences tend toward the "thin" negative, which may explain my outlook on the issue.
 

faberryman

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There is no standard process for "bleaching B&W paper in fixer". Bleaching speed strongly depends on fixer pH (which can in turn change with stop bath carryover - or developer carryover) and fixer strength/exhaustion. If you are unsure, take a fixed print and dip it halfway into your test fixer. Take note, when visible bleaching has occurred and fix your prints for less than that.

Having you ever performed the test you suggested? If so, at approximately what time did bleaching become visible? If not, have you ever experienced bleaching through overfixing on your own prints. If so, what fixer and dilution were you using, and how long were you fixing for?
 
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relistan

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Having you ever performed the test you suggested? If so, at approximately what time did bleaching become visible? If not, have you ever experienced bleaching through overfixing on your own prints. If so, what fixer and dilution were you using, and how long were you fixing for?

He did experience it, read more of the thread above.
 
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How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?
The test for inadequate washing is the Kodak HT-2 test for residual hypo. Cruise on over to unblinkingeye.com for the formula and the pdf (or jpeg?) of the comparison strip.
FWIW, the above is usually paired with a test for residual silver to check adequate fixation. Kodak ST-1 or the Kodak Rapid Selenium test are for this.

For testing overfixing for prints, just cut a print in strips and fix them, pulling a strip every, say, minutes till you get to 30 minutes or so. Dry them and compare. Any bleaching should be noticeable (if it's not, then the overfixing is obviously not an issue). For negatives, make several identical negatives, develop them identically and then fix for increasing times. Pull one at your normal fixing time, leave then next in 2x, the next 4x, etc. Ideally, you'd read corresponding parts of each negative for density values on a densitometer and compare. Alternatively, you can make proofs at the same exposure time (all on one sheet would be good) and compare those for signs of density loss in the negative.

Best,

Doremus
 

relistan

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I did. He said he left a print in the fixer for two hours and a portion of the print was bleached. Two hours.

It’s not clear to me what you want. Do you want to know the answer or are these rhetorical questions? If you want to know the answer, testing it seems reasonable, right? If it’s rhetorical as in, nobody should leave their prints in so long, then yes, we all agree.
 

faberryman

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It’s not clear to me what you want. Do you want to know the answer or are these rhetorical questions? If you want to know the answer, testing it seems reasonable, right? If it’s rhetorical as in, nobody should leave their prints in so long, then yes, we all agree.

Why don't you let Rudeofus answer the questions I asked him? He is the one who appears to have the most information on the topic of overfixing. Perhaps we will both learn something.
 
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relistan

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Why don't you let Rudeofus answer the questions I asked him? He is the one who appears to have the most information on the topic of overfixing. Perhaps we will both learn something.

I’m not preventing him from answering, he probably will when he’s online. Meanwhile the rest of us are having a discussion.
 

Rudeofus

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My information about overfixing is restricted to one dark room blunder, which is not a whole lot in the grand scheme of things. It involved a very acidic fixer (Agfa 304) and a fixing time, which none would ever knowingly chose (around 2 hours). I am confident, that I left prints in neutral fixer (which I have used ever since) longer than I should have, and the bleaching, if there was any, was very uniform and/or very weak - I did not notice a thing. I did not perform the thorough test as suggested by Doremus, but I took Ron's word, that neutral fixers "don't bleach". If you ever observed my sloppy and careless work, you'd quickly come to the conclusion, that a D=0.05 difference does not make much of a difference in my work flow.

Since more or less all fixers were "very acidic" 50 years ago, and since most subject related photographic literature comes from that time, the "bleaching through extended fixer time" theme is maybe more emphasized, than modern neutral fixers would warrant.
 

faberryman

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My information about overfixing is restricted to one dark room blunder, which is not a whole lot in the grand scheme of things. It involved a very acidic fixer (Agfa 304) and a fixing time, which none would ever knowingly chose (around 2 hours). I am confident, that I left prints in neutral fixer (which I have used ever since) longer than I should have, and the bleaching, if there was any, was very uniform and/or very weak - I did not notice a thing. I did not perform the thorough test as suggested by Doremus, but I took Ron's word, that neutral fixers "don't bleach". If you ever observed my sloppy and careless work, you'd quickly come to the conclusion, that a D=0.05 difference does not make much of a difference in my work flow.

Since more or less all fixers were "very acidic" 50 years ago, and since most subject related photographic literature comes from that time, the "bleaching through extended fixer time" theme is maybe more emphasized, than modern neutral fixers would warrant.

Thanks.
 
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