How reliable is the film clip fixer clearing test?

Given a fixer solution that is pale yellow, clear, and has no precipitate, does the film fixer clearing test prove the solution is still capable of adequately fixing film?

tl;dr
I have an unopened bottle of rapid fixer. According to the manufactirer's batch code, the fixer was made in Aug 2019 and has a recommended shelf life of 2 years. So the use-by date was Aug 2021. Since I've had it (Feb 2020), the fixer has been in a cool basement (65*-75*F/18-24*C), which is dim, but not totally dark.

Today, I mixed up a working solution of the fixer and did the "Film Fixer Clip Test" on a piece of fresh Ilford Delta 400 following the procedure posted <here>. Using dry film, the time was almost exactly 1 minute. Then I prewet the film and repeated the test, getting about 35 seconds. So, the fixer looks OK, right?

Except... When I contacted the manufacturer to decode the batch number, I was told,
"You could try a clearing test with a piece of film - but even thats not an ideal test - as we couldn't guarantee it will be archivally stable when notably old - even if it clears films in the times we guide (2-5mins) ... Personally, I think its unfortunately not worth risking..."

To say the test is not "ideal" is not very specific, but the tech is uncomfortable with it for some reason. I think it is probably just a case of being conservative, as company employees are no doubt trained to be - but she is the expert and I am not, so...?

Is a good clip test result all I need to know, or is there more to it than that?

The manufacturer is certainly going to take a conservative stance and I've been known to use expired fixer that passes a "clip test", but why risk it? Fixer is not expensive. Buy/mix some fresh stuff and eliminate the worry.

There are two questions when it comes to the health of fixer:
1) does it still retain the chemical capacity to fix film or paper; and
2) are their any indications that the fixer is deteriorating - "sulfuring out" - which can result in unwanted sulfur particles and related nasties coming out of solution.
A clip test is a reliable indicator with respect to the first question, but not the second.
FWIW, a "How To" resource about clip tests:
https://www.photrio.com/forum/resou...ixing-procedure-for-black-white-negatives.75/

Just out of interest whose fixer is it?

Thanks

pentaxuser

Alan9940 said:

The manufacturer is certainly going to take a conservative stance and I've been known to use expired fixer that passes a "clip test", but why risk it? Fixer is not expensive. Buy/mix some fresh stuff and eliminate the worry.

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It is not worry I am trying to eliminate, but ignorance (my own).

Many sources - including authors like Troop, Anchell, and Horenstein - say fixer potency can be verified by doing a film clip clearing test. But then a representative of a major film/chemistry manufacturer seems to be hinting that the test may not actually verify fixer potency (my interpretation of her words).

You and the factory tech person are both warning me about the potential risk of bad fixer - but the famous authors imply the test reduces/eliminates(?) the risk.

I just want to find out if the test is reliable, or not.

runswithsizzers said:

I just want to find out if the test is reliable, or not.

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It is - if you don't have issues with the other potential problem, sulfuring out.
Sulfur problems you can usually see and smell.

Twice the time it takes to clear.

It’s the kind of test to do when you re-use a batch for several rolls of film to know if it’s about time.

Or if you have to use a brand you’re not familiar with and unsure what dilution is right.

I use the test when water splashes into my fixer tray by mistake. But if too much splashed in I pour it out and start over.

But I think if it’s stinky - that’s a good backup test.

In your case everything sounds good to go.

MattKing said:

There are two questions when it comes to the health of fixer:
1) does it still retain the chemical capacity to fix film or paper; and
2) are their any indications that the fixer is deteriorating - "sulfuring out" - which can result in unwanted sulfur particles and related nasties coming out of solution.
A clip test is a reliable indicator with respect to the first question, but not the second.
FWIW, a "How To" resource about clip tests:
https://www.photrio.com/forum/resou...ixing-procedure-for-black-white-negatives.75/

Click to expand...

Matt, yes, it was your clip test procedure I followed. Thanks for that.

So if there is any yellow precipitate or cloudiness or sulfury smell, then there is no point in doing the clip test - just dispose of it and make new, right?

Bill Burk said:

Twice the time it takes to clear.

It’s the kind of test to do when you re-use a batch for several rolls of film to know if it’s about time.

Or if you have to use a brand you’re not familiar with and unsure what dilution is right.

I use the test when water splashes into my fixer tray by mistake. But if too much splashed in I pour it out and start over.

But I think if it’s stinky - that’s a good backup test.

In your case everything sounds good to go.

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So sulfur stinky is bad, but acetic acid stinky is good, right? (not sure about neutral/alkaline fixers - ammonia?)

I understand how the clearing time is applied when calculating how long film should stay in the fixer.

But I am less sure about how the result of the clearing test should be interpreted when deciding if the fixer is too old or too depleted. Is there some number that would be long enough to make us think, This fixer might be going bad? or, This fixer is definitely bad?

pentaxuser said:

Just out of interest whose fixer is it?

Thanks

pentaxuser

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It's Harman's Ilford Rapid Fixer. BTW, I have suggested they start putting some kind of actual date on their chemistry instead of "batch numbers" which require contacting Harman to find out how old the product is.

runswithsizzers said:

So if there is any yellow precipitate or cloudiness or sulfury smell, then there is no point in doing the clip test - just dispose of it and make new, right?

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Correct.

I have one of those bottles of liquid that check fixer life. You only need one or two drops to check out fixer life. Mine's lasted a decade over Lord knows how many gallons of fixer.

runswithsizzers said:

But I am less sure about how the result of the clearing test should be interpreted when deciding if the fixer is too old or too depleted. Is there some number that would be long enough to make us think, This fixer might be going bad? or, This fixer is definitely bad?

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If it hasn't sulfured out, and it is unused, it would almost certainly fix film quickly.
Many people see unused film fixer, diluted to film strength, clearing film in much less than one minute.
I usually don't see it that quickly, but anything in the range of two minutes makes me happy.

beemermark said:

I have one of those bottles of liquid that check fixer life. You only need one or two drops to check out fixer life. Mine's lasted a decade over Lord knows how many gallons of fixer.

Arista Premium Hypo Check - 1.0 oz.

Arista Premium Hypo Check - 1.0 oz. - Arista Premium Hypo Check is a liquid used to find out whether your fixer is exhausted.Use two drops in your fixer and, if there is residual silver in your fixer, the hypo check will…

www.freestylephoto.biz

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This is relevant to used fixer, because it reports on how much of the fixing byproducts are impeding future fixing, but probably tells you nothing about unused fixer.

MattKing said:

This is relevant to used fixer, because it reports on how much of the fixing byproducts are impeding future fixing, but probably tells you nothing about unused fixer.

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There is no difference between unused fixer and exhausted fixer. Actually I don't think is anything such thing as exhausted unused fixer and new fixer.

I use the clearing test on a regular basis but 'sulphuring out' can happen rapidly between sessions in the darkroom, sometimes it seems like it happens overnight, so go with your nose even if the film clears. But I definitely wouldn't dump the fixer on the basis of manufacturers usage guides as these will always be steered towards very conservative estimates.

beemermark said:

Actually I don't think is anything such thing as exhausted unused fixer and new fixer.

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However, there IS such a thing as unused fixer that has gone bad due to sulphuring out. While you could filter out the resulting solids and use the fixer, there might (will) be problems with fog (effectively undeveloped silver halides being sepia toned before they get a chance to fix out) and reduced fixer capacity.

Your hypo check won't tell anything useful about old fixer that might have gone bad as in the case of OP.

250swb said:

'sulphuring out' can happen rapidly between sessions in the darkroom, sometimes it seems like it happens overnight

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Unsurprisingly so, because an acid fixer will generally contain sulfite to protect the thiosulfate against decomposition. As soon as the sulfite runs out, the thiosulfate is next. Before the sulfite runs out, everything seems (and in fact, is) perfectly fine, but as soon as it's gone, things can go belly-up very fast, especially in a working stock that happens to be prone to oxygenation and that's already weak in sulfite due to dilution.

runswithsizzers said:

It's Harmon's Ilford Rapid Fixer. BTW, I have suggested they start putting some kind of actual date on their chemistry instead of "batch numbers" which require contacting Harmon to find out how old the product is.

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Thanks I checked on the tech sheets for Ilford Rapid fixer On page 5 of its tech sheets it says full unopened bottle stored in cool conditions (5 -20 degreesC) will keep for 2 years and this as others have said is probably a very conservative time. As your bottle was unopened then it will keep for 2 years which is Aug 2021 according to your batch number research so it's 14 months out of date, if you are right about the batch number giving a "made on" date

All I can say is that having used a number of bottles of Ilford Rapid Fixer since about 2005 I have used a lot of that fixer in an opened state for a lot longer than Ilford's recommended 6 months without problems of smell or precipitate You of course must be guided by how you feel is the safe limit

Incidentally can you or anyone else here for that matter, say how you work out the manufacture date from what I presume is the batch number on the bottle. That sounds worth knowing.

Thanks

pentaxuser

pentaxuser said:

Thanks I checked on the tech sheets for Ilford Rapid fixer On page 5 of its tech sheets it says full unopened bottle stored in cool conditions (5 -20 degreesC) will keep for 2 years and this as others have said is probably a very conservative time. As your bottle was unopened then it will keep for 2 years which is Aug 2021 according to your batch number research so it's 14 months out of date, if you are right about the batch number giving a "made on" date

All I can say is that having used a number of bottles of Ilford Rapid Fixer since about 2005 I have used a lot of that fixer in an opened state for a lot longer than Ilford's recommended 6 months without problems of smell or precipitate You of course must be guided by how you feel is the safe limit

Incidentally can you or anyone else here for that matter, say how you work out the manufacture date from what I presume is the batch number on the bottle. That sounds worth knowing.

Thanks

pentaxuser

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Thanks for sharing your experience with the fixer.

When I asked Harman about the batch numbers, I got this email reply,
"...we're always more than happy to help guide customers who contact us. So if you're ever want any items checking ... if you can let me know the batch numbers - I should be able to email you back the same day with my advice."
The email for Harman's Technical Services is <technical@harmantechnology.com>

But this brings up an interesting question about online retailers. When B&H Photo (a major online seller in the USA) fills my order, do they know if the products they are shipping are expired? Or are they as much in the dark as the rest of us?

For example, I recently got a box of Ilford Simplicity developer from B&H. After asking Harman to check the batch number, I learned the reagent was 21 months past Harman's recommended use-by date when it was shipped to me. I would guess that B&H's inventory software can somehow keep track of what is fresh and what is expired even when there is no expiration date on the packaging - but I don't know.

By the time I discovered B&H had shipped me expired developer, it was well past their 30-day return period. If there had been an expiration date on the box, I would have contacted B&H immediately. Fortunately, Harman offered to replace the Simplicity developer at no cost.

Going forward, I plan to try to buy my photo chemistry from manufacturers who mark their packaging with easy to understand dates - either a manufacturing date or an expiration date.

Sure fixer can get get old and fail, so that it no longer removes all the silver halide from the film. But the question in the title of "how reliable is the film clip clearing test?" should be, IMO, that it is pretty reliable. If the fixer does not leave particles on the film and if it clears the undeveloped silver halides (not leaving fog as mentioned by koraks), its job is done. You still have to get the remaining fixer out of the film by using a wash aid and wash, but after that, I don't think it is going to have any effect.

Harman is being careful in telling you not to use the fixer because they can't guarantee it past the expiration date, and they don't know if you test it before using (most people don't).

I would use the film clip clearing and hypo test. If there is still a question then get rid of it and start with fresh chemicals.

runswithsizzers said:

Thanks for sharing your experience with the fixer.

When I asked Harmon about the batch numbers, I got this email reply,
"...we're always more than happy to help guide customers who contact us. So if you're ever want any items checking ... if you can let me know the batch numbers - I should be able to email you back the same day with my advice."
The email for Harmon's Technical Services is <technical@harmantechnology.com>

But this brings up an interesting question about online retailers. When B&H Photo (a major online seller in the USA) fills my order, do they know if the products they are shipping are expired? Or are they as much in the dark as the rest of us?

For example, I recently got a box of Ilford Simplicity developer from B&H. After asking Harmon to check the batch number, I learned the reagent was 21 months past Harmon's recommended use-by date when it was shipped to me. I would guess that B&H's inventory software can somehow keep track of what is fresh and what is expired even when there is no expiration date on the packaging - but I don't know.

By the time I discovered B&H had shipped me expired developer, it was well past their 30-day return period. If there had been an expiration date on the box, I would have contacted B&H immediately. Fortunately, Harmon offered to replace the Simplicity developer at no cost.

Going forward, I plan to try to buy my photo chemistry from manufacturers who mark their packaging with easy to understand dates - either a manufacturing date or an expiration date.

Click to expand...

By the way.
This is a (Mark) Harmon:

Or if you prefer, so is this (the Angie version):

Harman Technology Ltd. are the folks who sell the photo chemicals.
And as I understand it, a large percentage of the sellers and manufacturers have moved away from putting dates on the chemicals, because they make it difficult for those retailers who still have store shelves to sell things.
A very large percentage of regular fixer users will be amazed that you think your fixer is old .

MattKing said:

as I understand it, a large percentage of the sellers and manufacturers have moved away from putting dates on the chemicals, because they make it difficult for those retailers who still have store shelves to sell things.

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... while ignoring the difficulties created for consumers.

The last time I bought Kodak chemistry the packages were still showing expiration dates.

Previous posts edited to correct egregious spelling faux pas. I sure won't make that mistake again! Glad to see Photrio is finally enforcing some high standards of accuracy around here. ;-)

runswithsizzers said:

Is a good clip test result all I need to know, or is there more to it than that?

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Yes, there's more to it than that.

Matt is pretty much spelling it out for you, plus see koraks post #15. (No need for me to repeat any of it, is there?)

When they talk about a fixer sulfuring out, this can happen when a thiosulfate-based fixer runs out of free sulfite ion. (Look up online formulas for any such fixer and you will see that they all include something like sodium sulfite - this supplies the sulfite ion.) Some tiny amount of the thiosulfate is always breaking down, leaving a free sulfur in the solution. If there is some free sulfite this combines with that unwanted sulfur, turning back into thiosulfate. So all is well until at some point the free sulfite ion is completely gone. At that point the fixer is on a path to destruction.

Now this is a somewhat insidious problem in that you probably won't be able to see anything until the problem is fairly bad. Personally I've never seen such results, since in the large chain outfit where I spent a lot of years, we never let it happen (full-time on-site chem lab). But the assumption is that some of the free sulfur could get entrained inside of the emulsion, potentially causing image stability problems down the road. PE (Ron Mowrey) on this site had occasionally commented on this possibility (wish he were still with us).

I guess the real question is, what can you do about it? Well, first, and most simplistically, throw it away when it hits the manufacturer's suggested age point. Second, take your chances and use it anyway (it's probably still ok.) Third, toss in a little extra sodium sulfite, for insurance, and use it. If you have time and some $ on your hands you could set up and do a chemical analysis for sulfite (see the Kodak H24 motion picture manual for details - they use a principle called iodimetry, doing a titration with "starch indicator" in the treated sample). Then add as much sulfite as needed.

Something else that a curious person might try, just to see if their fixer is close to the end (meaning out of sulfite) is to pull off a smallish sample and kill off some of the sulfite (aerate it, for example). Then let the sample sit a while and see if it begins to sulfur out. But... I've never tried this nor know how long it takes. So... who knows? I'd suggest to put the fixer sample in a larger jar, containg enough oxygen to oxidize 3 or 4 g/l of sodium sulfite (this should be a barely-safe level for using fixer). Then shake the jar up - the sulfite should oxidize pretty quickly. Then let it sit for a considerable time to see if it begins to sulfur out. Someone with a basic chemistry background could probably estimate the ratio of sample/air in the bottle.

One last comment with respect to how the manufacturer establishes shelf life. I had, at one time, seen some published analytical data on aging chemicals. This leads me to think that the standard method to set a shelf life is to first set an "acceptable tolerance" in the formula. (If it is Kodak or Fuji-Hunt they will have pretty stringent tolerances.) Then, the point where real-world samples exceed the tolerance would be the maximum shelf life. Of course, I can't say for sure that this is how they do it, but it seems a reasonable assumption. Amateurs tend to think that the criteria is, "it either works OK or it doesn't." But in pro use the chems need to perform as new, able to be replenished, etc., without excess oxidation or sludging, etc., as well as to be cycled through a silver recovery system, etc. So they're significantly different situations, with the amateur usage generally being much more tolerant.

runswithsizzers said:

Or are they (B&H Photo) as much in the dark as the rest of us?

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I'd be really surprised if B&H couldn't get the info they wanted. But... possibly it's confidential info, not to shared outside of the company.

Being from a former large outfit, meaning at one time a significant customer of Kodak, etc., we had access to pretty much any info we "needed." But it was all under a confidentiality agreement. No one wanted to abuse those privileges; as soon as the trust is broken, well, you probably wouldn't be getting it back.

runswithsizzers said:

... while ignoring the difficulties created for consumers.

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Actually, the change is mostly of no consequence for individual consumers, because mostly the shelf age of currently packaged fixer and similar products is immaterial - for individual consumers fixer lasts well past any likely "best before" date.
With normal storage - such as on a store shelf - the stuff really does last a very long time without problems.
Other products differ.

Sirius Glass said:

I would use the film clip clearing and hypo test. If there is still a question then get rid of it and start with fresh chemicals.

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...that would be the test for residual silver, not the residual hypo test. This latter tests whether the film or paper has been washed enough. A residual silver test is what you need to test for adequate fixation.

That said, a film-clearing test and a residual silver test should give you enough information to determine if your fixer is doing its job or not.

There are two readily-available ways to test for residual silver. The Kodak ST-1 test uses sodium sulfide:

Kodak® Residual Silver Test Solution ST-1
Distilled Water . . . . . . . . . . . . . . . . 125 ml
Sodium Sulfide (anhydrous) . . . . . . . 2 g
(This solution keeps for 3 months in a small tightly-sealed bottle.)

To use, dilute 1 part of the above stock solution with 9 parts distilled water. This working solution keeps less than a week. Squeegee your print or film and place one drop of the working solution on a border area. Let it sit for 3 minutes and blot with a clean cloth or tissue. Any discoloration other than a barely-visible cream tint indicates that your print or film still contains silver halides that require further fixing to remove.

An alternative is to use Kodak Rapid Selenium Toner. Kodak recommends a 1+9 dilution from stock, but tests show that a stronger dilution, even undiluted stock, works as well.

The directions are the same as the ST-1 test: wash your film or print adequately, apply a drop to the squeegeed material, let it for 3 minutes, blot and then check for stain. Any discoloration other than a barely-visible cream color indicates inadequate fixing.

I use the selenium toner test since I always have toner on hand.

If your old fixer clears film as fast as fresh fixer and the fixed material passes the residual silver test, you're good to go.

Doremus