30 second paper fixing?

Photo Engineer said:

Well, there were 2 answers hidden in that post Ralph. I'll answer both.

1. Diluting fixer changes the complexation ability (ratio) of hypo and ammonium ion towards the silver and changes the equillibrium. Look at it this way.... AgX (lots) and Hypo (lots) --> Complex (lots) + excess hypo (lots) but....

AgX(lots) and Hypo (Dlute but lots) --> Complex (lots) + excess hypo (dilute) ---> AgX(some) + free hypo again.

And, as the concentration of hypo changes, the type of complex changes. This is what Mees and James show.

2. Testing fix by making it a blix. The rate determining step in a blix is how fast the silver salt that forms can be removed from the coating. If the hypo is dead, the blix will bleach silver slowly to a brownish silver complex but fail to fix it. So, you get a discolored brownish or blackish strip of paper. If the hypo is active, all silver vanishes and leaves a white to yellow white strip of paper. So, the better the hypo, the whiter the strip becomes and the faster it changes.

I usually make a run with fresh fix and then know what the time is for a given paper and test as I go.

PE

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PE

Do I understand this right that the ammonium ferric turns the developed silver into a silver salt that the fixer can act upon again?

Ralph, that is the essence of a blix which is BLeach + fIX or BLIX. Ferric EDTA alone forms a gray brown material in the coating that is not fully soluable. The fix must be present to clear the film. However, this is not a rehal blix.

Remember that Ammonia in the fix and in the Ammonium Ferric EDTA will dissolve some silver salt from the coating and form odd complexes. This is normal.

Another approach is to mix Potassium Ferricyanide solution with your hypo. It will do the same thing only much more rapidly. It will destroy the hypo very quickly so the test must be ready to run or the hypo destruction by Ferricyanide will offset the test results.

There are many routes to this type of test for hypo exhaustion.

PE

Photo Engineer said:

Ralph, that is the essence of a blix which is BLeach + fIX or BLIX. Ferric EDTA alone forms a gray brown material in the coating that is not fully soluable. The fix must be present to clear the film. However, this is not a rehal blix.

Remember that Ammonia in the fix and in the Ammonium Ferric EDTA will dissolve some silver salt from the coating and form odd complexes. This is normal.

Another approach is to mix Potassium Ferricyanide solution with your hypo. It will do the same thing only much more rapidly. It will destroy the hypo very quickly so the test must be ready to run or the hypo destruction by Ferricyanide will offset the test results.

There are many routes to this type of test for hypo exhaustion.

PE

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PE

This makes a lot of sense to me. I will try it with a ferri-fix combo. You are right, that's not a very stable solution, but if mixed just prior to the test, it should work.

Thanks for the hint!

(Wogster) Makes one also wonder if there is a paper equivalent to the film fixer clip test.

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The test I would personally use, should I be suspicious of my fixer/paper combination, is this:

- condition a test strip of paper with developer and stop (or rinse, etc.)
- immerse 1 inch of test strip into fixer for 2 seconds, then another inch for 2 more seconds, then another inch for 2 seconds, etc, etc.
- quickly rinse the fixer out with running water, for perhaps a half minute or so.
- turn on the room lights, then redevelop the test strip in the light.

For evaluation, the strip will have darker patches wherever the silver halide was not entirely fixed out, and thus was able to be developed. So the first pure white section represents "clearing".

Obviously, there are finer details, such as marking the paper (notches, etc) at the intended immersion points, and any set of immersion times is ok, whatever you want. I'd consider this only a crude test, for comparison, you would ideally know the initial clearing time with freshly mixed fixer. For myself, I'd use the low end of manufacturer's fixing times, but make sure this time is comfortably more than triple the clear time.

If this were a community darkroom, and the condition of the fixer was unknown to me, I'd probably also want to do a silver-test-paper dip test. Or, bring my own 3rd tray plus fixer, or refix at home, etc.

Half Strength for Twice the Capacity

RalphLambrecht said:

I'm sure there is a difference, but I have limited my
process to film-strength fixer.

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In my post 40 this thread I chose not to go into the issue of
silver load limits. Ilford claims 40 8x10s through a liter of their
rapid fix at a dilution of 1:4. Silver levels hover around 2 grams
per liter. Although the chemistry's capacity is much higher, Ilford
recommendeds no more than that when fixing FB papers. Their
VOLUMETRIC limit for silver using FB papers is 2 grams or
0.5 gram when processing archival. Grant Haist has set
an archival limit of 0.2 grams.

Ilford rates their rapid fix at 200 8x10s per liter of concentrate
and they want us to have full measure and very well fixed prints
to boot. The upshot in 1981; they introduced the FILM strength
fix IN CONJUNCTION with a specific post fix wash-hca-wash;
the Ilford Archival Processing Sequence.

Importantly if one wishes their money's worth at film strength
they must settle for 40 8x10s and 2 grams silver per liter. To
make 0.5 with film strength, the liter of concentrate is
good for 50 8x10s. At paper strength, 100. Dan

archer said:

Dear Ralph;
While I agree that over fixing can be a serious problem and should be avoided if possible, I do not agree that it is anywhere near as bad as underfixing in long or short term permanence.
A poorly built house is eminently prefferable to a house that has burned down and must be rebuilt from scratch. A poor analogy perhaps but certainly germain.
Denise Libby

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I'll partly agree with you, even with rapid fixers, you need to over fix quite a bit before it affects the results. If the proper fixing time is 4 minutes 52 seconds and you fix for 5 or 10 minutes, it's not likely to have an adverse effect. It's unlikely to affect permanence all that much either, providing your paper washing process is good for fixing that length of time. Now if you fixed a sheet for say 5 hours, it's likely to affect the image and permanence doesn't then matter. Where it can affect the permanence is that the longer it sits in the fixer the more fixer the paper can absorb, an issue with FB papers, much less of an issue with film and RC papers. The more fixer in the paper, the harder it is to remove in a permanent manner. Under fixing definitely affects permanence, in that the residual silver halides will eventually darken ruining the print.

As for the house analogy, a poorly built house can be less preferable then one that has burned down, if it's built so poorly that the only way to fix it is to knock it down and rebuild it properly. The issue being now you have to pay demo costs as well as cleanup and building costs. Neither is preferable to determining a proper fixing time and then using that, the analogy being having a proper well built house that has not burned down.

wogster said:

... If the proper fixing time is 4 minutes 52 seconds and you fix for 5 or 10 minutes, it's not likely to have an adverse effect. It's unlikely to affect permanence all that much either, providing your paper washing process is good for fixing that length of time. Now if you fixed a sheet for say 5 hours, it's likely to affect the image and permanence doesn't then matter...

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I beg to differ. Doubling your fixing time from say 4 to 8 minutes will make it very hard to wash the fixer out of the emulsion. In my tests, it increased the washing time from 30 min to 2 hours to get to the same level of residual hypo in the emulsion. To fix as short as possible is almost as important as fixing as long as necessary in my opinion.

By the way, if you fix for 5 hours in rapid film-strength fixer, you don't have to worry about washing times anymore. Most of the image will be gone anyway. In any case, we must not forget over this discussion that 'real' photographic permanence requires toning.

My recommendation is:

1. two-bath fixing (as long as needed and as short as possible)
2. 10-60 min wash (depends on toner used in next step)
3. toning
4. 5-min wash
5. 10-min hypo clear
6. 30-min wash min (depends on water hardness and temp)

Photo Engineer said:

... when I want to run a test, I take about 5 ml of fix and 5 ml of the Ferric EDTA solution ...

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I had never heard of this test. Since you make mention of it as your way of testing, it must be, in some fashion, a better or more practical test than the "hypo Check" tests using Potassium Iodide. Can you comment on the respective merits and shortcomings of each sort of test?

Does the use of film strength fix for FB papers or the use of alkaline / neutral fixers affect the selection of the best test for fix exhaustion?

Thanks!

C

C;

Alkaline fixers are hard to work with in this test if the fix causes Ferric Hydroxide to precipitate. All tests have to be refined by the user as they are qualitative in nature. And, you never heard of the Ferric EDTA test because we used it internally at EK and never ended up publishing it. So, you can say you saw it here first.

The KI test is very very qualitative. Even a perfectly good but used fix can give a positive test with KI and fool you, but if the fix is bad with the FeEDTA test, it is BAD!

PE

Mr Bill said:

The test I would personally use, should I be suspicious
of my fixer/paper combination, is this:

- condition a test strip of paper with developer and stop
(or rinse, etc.) - immerse 1 inch of test strip into fixer for
2 seconds, then another inch for 2 more seconds, then another
inch for 2 seconds, etc, etc. - quickly rinse the fixer out with
running water, for perhaps a half minute or so. - turn on the
room lights, then redevelop the test strip in the light.

For evaluation, the strip will have darker patches wherever
the silver halide was not entirely fixed out, ...

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I'd be concerned with the residual silver left in the emulsion
with such a short after fix 'wash'. Even very minute amounts
of silver left in the emulsion when exposed to room lighting
will darken giving a false reading. The fix may have done
it's job but some clinging silver remains. Dan

[Dan] Even very minute amounts of silver left in the emulsion when exposed to room lighting will darken giving a false reading.

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Dan, it's a screening test for fixer, similar in purpose to a film clearing test. It is NOT to search for small amounts of residual silver. It is to find the approximate fixing time at which nearly all silver halide can be dissolved - same as a film clearing test.

To be more clear about the "darker patches" I mentioned; they will typically go from very dark to white with perhaps 1 or 2 steps of moderate gray. I think that it would be very difficult to misinterpret the results of this test, even for a novice. The step where the drastic change to white occurs, where all white patches look the same, is the endpoint of the test.

I should probably point out that this test does not prove that the fixer is suitable for use, however if the fixer is grossly deficient, this would probably be identified.

I should have perhaps been more clear in the purpose of this test.