Fix bath test

I've found two formulation to prepare fix bath test solution:

- using 50 g / l of potassium iodide or

- using 190 g / l of the same salt

What is the best?

Thanks

ziocalepino

And I use10% (= 100 g / l). Am I doing something stupid...?

Jan

"piterengel" schreef in bericht
m...
I've found two formulation to prepare fix bath test solution:

- using 50 g / l of potassium iodide or

- using 190 g / l of the same salt

What is the best?

Thanks

ziocalepino

RE
I've found two formulation to prepare fix bath test solution:
- using 50 g / l of potassium iodide or
- using 190 g / l of the same salt
What is the best?

Both will work though approximately four times as much of the
50gr/ltr solution will be needed. If counting drops is no bother,
the more drop method will give you a more accurate quantitative
result.
A weakness of the usuall test method is that it does not really
give a good indication of how close is the fix to exhaustion. A
fix may pass the usuall test then after the next roll of film
or two or three prints, it may fail. The many drop method
may help pin down just how much life is left. Dan

Dan,

can you describe that method, please?

Jan

"Dan Quinn" schreef in bericht
m...
RE
I've found two formulation to prepare fix bath test solution:
- using 50 g / l of potassium iodide or
- using 190 g / l of the same salt
What is the best?

Both will work though approximately four times as much of the
50gr/ltr solution will be needed. If counting drops is no bother,
the more drop method will give you a more accurate quantitative
result.
A weakness of the usuall test method is that it does not really
give a good indication of how close is the fix to exhaustion. A
fix may pass the usuall test then after the next roll of film
or two or three prints, it may fail. The many drop method
may help pin down just how much life is left. Dan

"Jan T" wrote

And I use10% (= 100 g / l). Am I doing something stupid...?

WE may be doing something stupid. I think perhaps that the
iodide test is another of those one ... fits-all recommendations.
The usuall thiosulfate fix, sodium or ammonium, can take up small
amounts of silver in the presence of small amounts of iodide.
But the same fix can take up large amounts of silver in the presence
of it's chloride and bromide. In fact in the presence of chloride and
to a lesser extent bromide, silver may be complexed by the ammonia.
The iodide test is important in my work because I use fixer one-
shot and do not wish to waste it. I conducted a fix test some time ago
with iodide and then tested with bromide. Where the iodide produced
a precipitate with a few drops the bromide did not with several
times as much of it added.
I will be doing more titration tests with iodide and bromide.
BUT, there is a relation ship twixt the iodide and bromide tests.
If the ratios are correct then the iodide test is valid. I'll have to
do some more tests to come to an accurate quantitative determination.
I think though you can see my point. If in the fix test I made,
a very few drops of iodide made for, but a nearly endless number
of bromide made not for a precipitate, then how close to
accurate can the test be? Dan

"piterengel" wrote in message
m...
I've found two formulation to prepare fix bath test
solution:

- using 50 g / l of potassium iodide or

- using 190 g / l of the same salt

What is the best?

Thanks

ziocalepino

Here is Kodak's formula:

Kodak FT-1 Fixer Bath Test Solution

Water at 80F (27C) 750.0 ml
Potassium Iodide 190.0 grams
Water to make 1.0 liter

To test a single bath fixer: To 5 drops of the test
solution, add 5 drops of the fixing bath and 5 drops of
water. Discard the fixer if a yellow-white precipitate forms
instantly. Disregard any slight milkiness.

Two Bath Fixer:
First Bath: Test as described above for a single bath.
Second Bath: To 5 drops of test solution add 5 drops of
fixing solution plus 15 drops of water.
If _both_ tests produce a yellow-white precipitate, replace
both baths with fresh baths. If only the first bath forms a
precipitate, replace the forst bath withyt the second bath,
and replace the second bath with a fresh bath.
The test solution can be stored for one year in a stoppered
brown bottle.

A liter of this stuff is a lifetime supply. The formulas
are standardized to 1.0 liter. I think 50 ml is a more
practical amount.
This test works on either sodium or ammonium (rapid)
fixers although the criteria above are probably for sodium
thiosulfate and prints.

The formula you have using 50 grams per liter is about the
same as the diluted version of this test for single bath
fixers.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote

Here is Kodak's formula:
Kodak FT-1 Fixer Bath Test Solution
Water at 80F (27C) 750.0 ml
Potassium Iodide 190.0 grams
Water to make 1.0 liter

To test a single bath fixer: To 5 drops of the test
solution, add 5 drops of the fixing bath and 5 drops of
water. Discard the fixer if a yellow-white precipitate forms
instantly. Disregard any slight milkiness.

Those directions are telling us to add 5 drops fixing bath to
5 drops of 19% KI solution. That is an unrealistic test save for
possably one. That one would be a single bath archival fix. Silver
levels as you know must be very low in a first and only fix to
achieve archival results.
I'm quite sure bath one and two fixers have been reversed. That
is, 15 drops of water should be added to test bath one and 5 drops
added to bath two. That will dilute bath two less and make for a
more sensitive test. Bath two silver levels are to be kept
extremly low.
One more thing, this FT-1 test is for, if anything, Fiber Base
paper ONLY. Quite frankly I'm not sure the FT-1 test is good for
anything but selling more fixer.
Subclub recommends two, 2, DROPS same strength in 2 OUNCES
of fix. My bottle of Fix-A-Sure recommends one, 1, DROP in 1
OUNCE. Those two are mentioned only by way of contrast. Dan

Two Bath Fixer:
First Bath: Test as described above for a single bath.
Second Bath: To 5 drops of test solution add 5 drops of
fixing solution plus 15 drops of water.
If _both_ tests produce a yellow-white precipitate, replace
both baths with fresh baths. If only the first bath forms a
precipitate, replace the forst bath withyt the second bath,
and replace the second bath with a fresh bath.
The test solution can be stored for one year in a stoppered
brown bottle.

A liter of this stuff is a lifetime supply. The formulas
are standardized to 1.0 liter. I think 50 ml is a more
practical amount.
This test works on either sodium or ammonium (rapid)
fixers although the criteria above are probably for sodium
thiosulfate and prints.

The formula you have using 50 grams per liter is about the
same as the diluted version of this test for single bath
fixers.

(Dan Quinn) wrote in message . com...
"Richard Knoppow" wrote

Here is Kodak's formula:
Kodak FT-1 Fixer Bath Test Solution
Water at 80F (27C) 750.0 ml
Potassium Iodide 190.0 grams
Water to make 1.0 liter

To test a single bath fixer: To 5 drops of the test
solution, add 5 drops of the fixing bath and 5 drops of
water. Discard the fixer if a yellow-white precipitate forms
instantly. Disregard any slight milkiness.

Those directions are telling us to add 5 drops fixing bath to
5 drops of 19% KI solution. That is an unrealistic test save for
possably one. That one would be a single bath archival fix. Silver
levels as you know must be very low in a first and only fix to
achieve archival results.
I'm quite sure bath one and two fixers have been reversed. That
is, 15 drops of water should be added to test bath one and 5 drops
added to bath two. That will dilute bath two less and make for a
more sensitive test. Bath two silver levels are to be kept
extremly low.
One more thing, this FT-1 test is for, if anything, Fiber Base
paper ONLY. Quite frankly I'm not sure the FT-1 test is good for
anything but selling more fixer.
Subclub recommends two, 2, DROPS same strength in 2 OUNCES
of fix. My bottle of Fix-A-Sure recommends one, 1, DROP in 1
OUNCE. Those two are mentioned only by way of contrast. Dan

Two Bath Fixer:
First Bath: Test as described above for a single bath.
Second Bath: To 5 drops of test solution add 5 drops of
fixing solution plus 15 drops of water.
If _both_ tests produce a yellow-white precipitate, replace
both baths with fresh baths. If only the first bath forms a
precipitate, replace the forst bath withyt the second bath,
and replace the second bath with a fresh bath.
The test solution can be stored for one year in a stoppered
brown bottle.

A liter of this stuff is a lifetime supply. The formulas
are standardized to 1.0 liter. I think 50 ml is a more
practical amount.
This test works on either sodium or ammonium (rapid)
fixers although the criteria above are probably for sodium
thiosulfate and prints.

The formula you have using 50 grams per liter is about the
same as the diluted version of this test for single bath
fixers.

The test for a single bath is 5 drops of test solution _and_ five
drops of water to 5 drops of fixer. That's not 19%. The concentration
of the mixture is about 6.3%.
The tollerable concentration for the second bath is much less
than for the first since it must have low enough silver concentration
to function as the first bath.
I do agree that one would expect a more sensitive test for a
single bath than for the first bath of a two bath system. It may be
that there is an error is the instructions. They came from the _Kodak
Black and White Darkroom Dataguide_ I've found examples of
instructions in Kodak publications that have lost something in
translation at some point. I don't know what the original source of
the test formulas is. Probably one of the Kodak Labs research papers.
The capacity of a single bath for "archival" fixing of paper is
astonishingly limited. According to Ilford figures its only about 10
8x10 sheets per _gallon_. The capacity of a two bath system is at
least four times this and probably much more than that. Kodak used to
rate both fixing and washing as either "commercial" or "archival".
Commercial processing had a life expectancy of 25 years. Since the
capacity of a two bath system for archival fixing is enough to make it
economical there is no good reason to use the less permanent standard.
Since neither Kodak or other makers of Iodide test solutions seem to
publish the approximate silver concentration that results in an
indication they are of use mainly as a guide. Further, the use of a
sulfite wash aid will make some otherwise insoluble reaction products
soluble, or at least removable, thus indirectly increasing the
capacity of the fixing bath.
Capacity depends on the nature of the emulsion. Fixing time and
capacity is actually about the same for fiber paper as it is for RC.
The emulsions are about the same. Film has a different kind of
emulsion, generally thicker, with a greater concentration of halides,
and with more silver iodide. All of these result in longer fixing
times. Typical paper emulsion will fix out completely in two minutes
in a Sodium thiosulfate fixer, perhaps even faster. Typical film
emulsion takes perhaps 6 minutes in fresh sodium fixer but can take
longer. Emulsions with a lot of Silver Iodide, like Tri-X or any of
the tabular grain films, take considerably longer, probably ten
minutes in sodium fixer. Ammonium thiosulfate has a distinct advantage
in fixing these emulsions.
Fixing time varies with the silver concentration in the fixing
bath. A very large excess of free thiosulfate ions must be present to
complete the fixing. Note that clearing of the emulsion, that is,
making it visually transparent, does not signify complete fixing.
While a fresh fixer may fix in the clearing time used fixer will not.
The old rule of fixing for twice the clearing time is a good one but
sufficiently used fixer may not fix in any amount of time although it
still clears the emulsion. Since any resudual silver halide will
eventually decompose and attack the image good fixing is important.
Probably a better test of fixing is a residual silver test of the
emulsion rather than a silver concentration test of the fixing bath.
Residual halide may be tested by using a Sodium Sulfide solution or a
1:9 dilution of Kodak Rapid Selenium Toner. Both stain the halide. The
toner is a more stable test solution but works only on well washed
emulsion, it fails where there is a large excess of hypo present. Well
fixed emulsion should show no stain. One problem with either test is
that its hard to see the stain on tinted stock. Very little of that is
currently in use so it is a very useful test.

Richard Knoppow
Los Angeles, CA, USA

"Jan T" wrote

Dan,
can you describe that method, please? Jan

RE
I've found two formulation to prepare fix bath test solution:
- using 50 g / l of potassium iodide or
- using 190 g / l of the same salt
What is the best?

Both will work though approximately four times as much of the
50gr/ltr solution will be needed. If counting drops is no bother,
the more drop method will give you a more accurate quantitative
result.
A weakness of the usuall test method is that it does not really
give a good indication of how close is the fix to exhaustion. A
fix may pass the usuall test then after the next roll of film
or two or three prints, it may fail. The many drop method
may help pin down just how much life is left. Dan

The Kodak FT-1 and Subclub, Fix-A-Sure tests referred to in
another post this thread, represent the extrems.
The Kodak test and the other one-drop-in an-ounce tests are at
opposite ends of the spectrum. One drop in one ounce is no margine
at all.
I see I've 5% KI. The 10% you use should show no precipitate
with a few drops in 10ml. That is my opinion. I think I would feel
safe with that. Do the test slowly, one drop at a time, and
stir or shake.
I've yet to read anything at all which delves into the subject
of fixer testing. Considering the importance of fixation, I think
the lack of information a real oversight.
Some films and most papers have no silver iodides. Fixer has a
great capacity for the chloride and bromide. Is the iodide test
relevant? If so how is it related?
The test itself, is it for film, RC or FB paper? In all cases
capacity is not the measure. In fact the capacity of all usuall
fixers surpass their usefullness; the more true with FB
archivaly processed. Dan