hypo check: what am i looking for?

RalphLambrecht · Apr 29, 2010

dancqu said:
...The problem with FT-1 type tests is there lack of quantification.
The test is actually a titration with no quantities specified. Very
un-scientific. The closest I've found to scientific is Kodak's
FT-1 test. And it is questionable. Dan

Dan gave a perfect explanation. I'm not sure what Dan means with 'Kodak's FT-1 test', but the Darkroom Cookbook shows a modification where 1 ml of a 5% potassium iodide test solution is added to 10 ml of fixer. If a cloudy precipitate remains, the fixer is exhausted. I think the test is OK for commercial film and RC paper development, detecting residual silver levels above 2 g/l, but it cannot be used for an 'archival' workflow.

Kirk Keyes · Apr 29, 2010

In addition to Ralph's comments, hypo check is quite useful in double bath fixing. When the first bath starts to have a lingering precipitate, then retire that first fix bath, replace it with the second fix bath, and then prepare a fresh second fix.

clayne · Apr 29, 2010

I basically always refer back to this:

http://groups.google.com/group/rec.photo.darkroom/msg/8b3734be8e11982b?hl=en&dmode=source

CBG · Apr 30, 2010

Excellent article.

Doremus Scudder · Apr 30, 2010

Discrepancy in Gudzinowicz's article?

I read Dr. Gudzinowicz's article some years ago and had questions about it at the time. Maybe someone here, this time, will be able to address them.

In the work that Gudzinowicz quotes from Grant Haist, there seems to be a discrepancy in the volume units used. The silver levels are given in grams per liter g/l, but the fixer volume is given as 1 gallon (e.g. rolls/gal.)

Given the rather low figures for capacity, even for commercial processing, I believe the gallon unit to be an error. By substituting liter for gallon in the tables, one arrives at fixer capacities that are much more in line with Kodak's (and others') published data on fixer capacities.

I have been using the procedures outlined by Gudzinowicz in this article for some time now, however, with the capacities revised to reflect the smaller fixer quantity.

I would love for PE or someone who is more familiar with Haist's work to comment on this.

Looking forward to a definitive answer this time...

Doremus Scudder
www.DoremusScudder.com

RalphLambrecht · Apr 30, 2010

Doremus Scudder said:
...In the work that Gudzinowicz quotes from Grant Haist, there seems to be a discrepancy in the volume units used. The silver levels are given in grams per liter g/l, but the fixer volume is given as 1 gallon (e.g. rolls/gal.)...

The numbers and units quoted in the paper match the numbers in Grant Haist's book on page 641.

clayne · May 1, 2010

RalphLambrecht said:
The numbers and units quoted in the paper match the numbers in Grant Haist's book on page 641.

Speaking of books, what's the status of WBM right now, Ralph? I can't find it for anything less than 200$ and that's a bit much for me after paying ransom for Tim's toning book.

RalphLambrecht · May 1, 2010

clayne said:
Speaking of books, what's the status of WBM right now, Ralph? I can't find it for anything less than 200$ and that's a bit much for me after paying ransom for Tim's toning book.

Way Beyond Monochrome Ed2 is well on track. There have been a few organizational hurdles, which are all resolved now. I promised to make an announcement with exact publication date by May 11th in the Partner/Sponsor section of APUG, and to all people on the mailing list. If you have not done so already, add yourself to the mailing list here:

http://www.waybeyondmonochrome.com/WBM2/Where_to_Buy.html

Save your money, the cover price will be far less than $200.

Now, let's get back to the topic.

Doremus Scudder · May 1, 2010

Ralph,

Thanks for the reply. My confusion remains however. I'll reformulate my suspicions referring to one product only: good old Kodak powdered fixer (F5) for use with conventional (i.e., non-T-Max) films.

If, as Haist states, with one-bath fixation, and fixing to "commercial" standards (which he gives as 1,5g/l of dissolved silver) the capacity of the fixer is 25 rolls or 100 4x5 sheets of film per gallon (which translates to 25 8x10 sheets per gallon), how in the world can Kodak recommend four times that capacity for the same fixer in their technical publications?

The official capacity for Kodak fixer from Kodak (from their tech. pub. "CHEMICALS FOR KODAK PROFESSIONAL BLACK-AND-WHITE FILMS") is 100 8x10 sheets per gallon or 26 sheets per liter.

The factor of the difference between Haist and the official Kodak publication seems too coincidental to overlook. First, I find it doubtful that Kodak would be recommending a "commercial" standard that used four times the capacity recommended by one of their top researchers. I can't imagine how the fixer would be anywhere near workable with four times the dissolved silver, not to mention thiosulfate exhaustion.

Second, the fact that a liter (or, more exactly, a quart) is a fourth of a gallon leads me to suspect an error in copying data somewhere. The fact that Haist seems to be using the metric system (e.g., g/l of Ag conc.) in other places plus the disparity with Kodak themselves as well as published capacities from other sources (Ilford, Formulary, etc.) leads me to think that he intended liters, not gallons as the unit in his tables. Substituting liters for gallons in Haist's tables (the ones in Gudzinowicz anyway) resolves the discrepancy between Kodak's official capacities and Haist's recommendations.

Finally, when Haist was doing his research and writing, Kodak was using the United States customary system for all their products in the States, while Haist in the lab was undoubtedly using metric measurements, making an error in basic unit more of a possibility when the book was being prepared (likely by assistants or secretaries).

My next question to you and anyone else interested: How do you resolve the discrepancy between Haist's numbers and the official capacities of fixers from Kodak and others?

TIA and best,

Doremus Scudder
www.DoremusScudder.com

RalphLambrecht · May 1, 2010

We could measure it ourselves? Use some silver-test paper from Tetenal, fix a Zone-V exposed film (average case) in the minimum amount possible (250 ml?), test for silver content and do the math. The test paper is not very precise (0.25 g/l maybe) but close enough to prove or disprove your assumption that units were confused.

Fixing a film in 250 ml is roughly equivalent to 15 films in a gallon. So, the paper should show about 1 g/l silver if Haist is right. If you are correct, then the paper should not indicate any silver, because it does not read below 0.5 g/l.

dancqu · May 1, 2010

Method and Silver Levels

Doremus Scudder said:
In the work that Gudzinowicz quotes from Grant Haist,
there seems to be a discrepancy in the volume units used.
Looking forward to a definitive answer this time...

I've studied Dr. Gudzinowicz article and quote from Grant
Haist. As you say silver levels by Grant's reckoning are
extremely low. But who's to say what the levels might
be? Ilford by a factor of ten greater claims great LE.

Have you read the doctor's critic of Ilford's Archival
Processing Sequence? There the Dr questions that
method. By Ilford's reckoning silver levels in the
fixer can equal those of commercial processing;
specifically 40 8x10s through 1 liter. And still
achieve archival results; great LE.

By the method I use, very dilute one-shot fixer --
But that's another story. Dan

RalphLambrecht · May 1, 2010

I have fully changed over to Haist's and Gudzinowicz's recommendation of two-bath fixing. With rotary processing, this uses a minium amount of chemicals and leaves nothing to worry about. I'll measure the silver content in the first bath next time and report back.

Photo Engineer · May 1, 2010

Exhaustion of fixer is a complex subject and testing for exhaustion is just as complex.

Basically, both events are functions of the type of film or paper put through a given fixer and it will vary with the fixer.

The best test for any fixer is the leader test. Dip in a small strip of leader and watch from the base side. The film will clear. Fix time is 2x the clear time. If the film requires longer and longer clear times, this is normal. Failing to clear is a definite warning that the fixer is dead. However, passing the test does not mean the fixer is good.

In an example, first you must know that many complexes of Silver Halides are formed by fixers. Mees lists several of them. They wash out at different rates. Some wash out poorly and others do not. As a fixer is exhausted, it can form more stubborn complexes that will not wash out as rapidly as the original fixer allowed.

Therefore, the leader test and the wash test are needed to assure proper fixing and washing. You should consider these two steps to be one operation, ie. removal of excess Silver Halide. The retained Silver test should also be part of your test repertoire.

I have had two papers that tested about 2x different in both fix and wash times. The one that took longer had more addenda in it including Iodide. I was able to test both papers for addenda. So, there are no hard and fast rules except your personal tests under your conditions.

PE

Doremus Scudder · May 2, 2010

First, a correction: I noticed I should have stated "residual silver" in my post above. Sorry for any confusion.

And, I guess, apologies for hijacking the thread. However, it has become quite interesting.

I have also revised my fixing procedures lately. Either two-bath or dilute one-shot fixation for film now, depending on the number of sheets I have to develop. What I'm trying to ascertain here is a way to deal with fixing times, and fixer exhaustion and capacity.

I do realize that different materials require different fixing time and use up fixer at different rates. I use clip tests and residual silver tests (the latter mostly for prints). My confusion arises from the widely disparate recommendations, both for times and capacities. For example, Gudzinowicz recommends fixing for 4x the clearing time for film; 2x in each bath of the two-bath fixing scheme. Many (including PE just now) seem to recommend 2x clearing time. Anchell/Troop in one of their books recommend 3x for modern-emulsion films. Likewise, the capacity recommendations are all over the place. I realize this is a complex subject, but it appears that some advice (Haist via Gudzinowicz) is at odds with manufacturers' recommendations, even for "commercial" levels of residual silver...

Is there any way we can nail this down a bit? For now, I will err on the side of caution, tossing fixer well before it should be exhausted. However, it's still hard for me to swallow the assertion that I need a gallon of fixer to "archivally" fix 8 sheets of 4x5 film (the table from Haist in Gudzinowicz). PE, would you like to comment on that please? Any guidelines, comments, etc. would be most welcome.

Best,

Doremus Scudder

clayne · May 2, 2010

Doremus Scudder said:
Is there any way we can nail this down a bit? For now, I will err on the side of caution, tossing fixer well before it should be exhausted. However, it's still hard for me to swallow the assertion that I need a gallon of fixer to "archivally" fix 8 sheets of 4x5 film (the table from Haist in Gudzinowicz). PE, would you like to comment on that please? Any guidelines, comments, etc. would be most welcome.

Best,

Doremus Scudder

I empathize with your search for correct answers Doremus. 8 4x5 sheets per gallon is way too little just based on a gut feeling. That's like 4 short rolls of 135 per gallon. It just can't be. A liter, as you mentioned, seems more in line.

RalphLambrecht · May 2, 2010

Doremus Scudder said:
...Is there any way we can nail this down a bit? For now, I will err on the side of caution, tossing fixer well before it should be exhausted. However, it's still hard for me to swallow the assertion that I need a gallon of fixer to "archivally" fix 8 sheets of 4x5 film (the table from Haist in Gudzinowicz). PE, would you like to comment on that please? Any guidelines, comments, etc. would be most welcome...

Sorry for not being PE, but a guideline to verify this for yourself was given in post #35.

RalphLambrecht · May 2, 2010

clayne said:
I empathize with your search for correct answers Doremus. 8 4x5 sheets per gallon is way too little just based on a gut feeling. That's like 4 short rolls of 135 per gallon. It just can't be. A liter, as you mentioned, seems more in line.

I think Gudzinowicz and Haist are misunderstood here. To me, the real message is:

If you want to compete with two-bath fixing, your single-bath fixer capacity is very limited. Two-bath fixing is not a waste of fixer, it's a huge fixer saving. Forget single-bath fixing if you are interested in archival processing.

My test proposal will reveal if there is a mixup of units, but I doubt it.

Doremus Scudder · May 3, 2010

Ralph,

I was not trying to slight you in the least! Your expertise and insight is invaluable and most welcome. And, I will be doing some more extensive testing on this, as you suggested, when I'm able to work in my (better equipped) Oregon darkroom. Unfortunately, that won't be till July.

However, not being a chemist, nor having easy access to the research materials (which I may not understand even if I did), relegates my testing efforts to the realm of the amateur, I fear.

I was hoping that those of us with more expertise and experience in well-equipped research labs, background in photochemistry and engineering and/or access to and understanding of research, including yourself of course, could give those of us with less technical backgrounds some more concrete guidelines for fixation times and fixer capacities.

Certainly, it would seem that two-bath fixing is indicated for most cases, but should I fix for 2x, 3x, or 4x the clearing time?

Is a clip test a reliable indicator of fixer exhaustion? And can I feel confident using my fixer till the clearing time reaches 2x that of fresh fixer?

What levels of dissolved silver in the fixer is acceptable for optimum permanence? 0 g/l as Haist uses, or 0.5 g/l as Ilford recommends or ? Are these levels the same for prints and films (I think not but...)?

As for capacities, can I keep using those recommended by manufacturers, or, in light of Haist/Gudinowicz, do I need to revise those figures? For that matter, what standard of permanence are Kodak's recommendations based on (Ilford is rather more clear on this issue, but their science seems to be called into question by some)?

Unfortunately, the information is not always easy to come by, and often contradictory. It is precisely these contradictions and dispariteies that I was hoping those more knowledgeable than myself would address. I'm still hoping...

Best,

Doremus Scudder

Photo Engineer · May 3, 2010

Well, I'll restate what I said in my other post but use different words.

If you run a leader test on any fixer and the leader clears, the 2x the clear time is the fixer time FOR THAT FILM.

Then, if you wash that leader using your normal film wash cycle for that film and it test free of hypo and silver, then the fixer is still good. For proper longevity of film and paper, a tiny amount of hypo is needed, remaining in the coating as shown by the Kodak tests. There is a slight residual color.

Note that only the combined fix and wash tests will really reveal whether the fixer is good or not.

PE

RalphLambrecht · May 3, 2010

Doremus

You are making this too hard for yourself. I advise to stick to two-bath fixing (film or paper) and the values listed by Haist and Gudzinowicz for archival processing. This will give you reasonable capacities and piece of mind. If you want to do more, do the clip test for film, as PE suggested, or get comfortable with one-shot processing.

clayne · May 3, 2010

Ralph, but what if the values are actually wrong and it's possible 2-bath fixing is acutally capable of going much further? You have to admit that the single-bath values seem extremely conservative - and as such the two-bath values would also be affected by a factor of 3.8 (gal vs liter) if what is being questioned has some validity to it. With the single bath values it's 4 rolls of 135 film per *gallon* before it's considered non-archival. That seems very low.

RalphLambrecht · May 3, 2010

clayne said:
Ralph, but what if the values are actually wrong and it's possible 2-bath fixing is acutally capable of going much further?...

Forget the possibility of a mistake or the opportunity of going further for a moment, and let's look at all the film data in the table in order to understand the message. Here is how I read it:

The table starts with predetermined values for residual silver levels, which are acceptable for commercial and archival use. For example, Haist assumes the commercial value for residual silver in film to be at 0.01 mg/in^2.

He claims, that this much silver is left in the films if 25 films/gallon are fixed with single-bath fixing, or 60-70 films/gallon are fixed with two-bath fixing.

In the next example, Haist sets the archival value for film to nil. In other word, stop using the fixer as soon as you can detect any residual silver in the film. According to him, this happens after only 2 films/gallon with single-bath fixing, but 40 films/gallon can be fixed with two-bath fixing before silver becomes detectable in the films.

In addition, he also lists the amounts of accumulated silver in the fixing baths for all conditions, because they are much easier to measure than residual silver levels in the film itself.

I see nothing wrong with the table, and I don't think there is a mixup of units either, but I understand the message to be: single-bath fixing is a big waste of fixer if you want an archival process.

I'm sure, you can take single and two-bath fixing further than the capacity limits Haist describes, but then you have to change the assumptions of residual silver limits in film and paper too, and I see no evidence to safely do so.

Photo Engineer · May 3, 2010

Having formulated several fixers and bleaches on photo imaging and also having patents on the chemistry, I feel that I am outclassed by the present company. Sorry. I bow out of this discussion.

PE

dancqu · May 3, 2010

Capacity Varies

Photo Engineer said:
Note that only the combined fix and wash tests will really
reveal whether the fixer is good or not. PE

And that only under the specific conditions used in
processing. Ron is suggesting that post fix procedures
will affect permissible silver levels. See my post 36
this thread dealing with method and silver levels.

When going for great LE chemical capacity ordinarily far
exceeds silver limits. For that matter commercial levels
of silver are way below chemical capacity. The only
exception is my use of very dilute fixer used one-
shot. The silver limit per unit volume is not an
issue. Silver levels are always well within
Ilford's standard for great LE. Dan

Dave in Kansas · May 4, 2010

This thread was perfect timing for me. After developing a roll of film last night I began wondering if my fixer was still good. It was great reading about the leader test, something I've never done in all my years of developing. I've always just guessed or used hypo check. I just found my unused leader from last night and tested it and learned my fixer is still good, according to that test. I felt so good about this that I renewed my Apug subscription!

Dave

hypo check: what am i looking for?

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