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Capacity/life of rapid fixer



 
 
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  #1  
Old April 4th 10, 07:52 PM posted to rec.photo.darkroom
Stefan Patric[_3_]
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Posts: 19
Default Capacity/life of rapid fixer

On Sun, 04 Apr 2010 03:29:41 -0700, sreenath wrote:

Hi,

I am using a rapid fixer sold in India be the name "Agefix" The
instructions that come with the bottle just suggests a dilution of 3-5
times for film.

I have been using the suggested dilution with no problem.

My question is the capacity of this diluted fixer. I kept using the 1
liter for more than a year. Every time I do a film clip test and observe
that film clears very quickly.

Is it possible for the fixer to clear the film clipping but still be
unable to fix the film completely?

Are there any other tests for fixers?


Agefix is an Agfa product. With standard dilution, no replenishment, 1
liter will fix 1 square meter of film before the fixer is exhausted.
That's about 20 rolls of 36 exposure, 35mm film.

Here's a link to the Agfa film chemistry pdf. The Agefix info is on page
12 of the document.

http://www.cri.ensmp.fr/~silber/photo/docs/films.pdf


Stef
  #2  
Old April 4th 10, 10:33 PM posted to rec.photo.darkroom
Richard Knoppow
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Posts: 751
Default Capacity/life of rapid fixer


"Stefan Patric" wrote in message
...
On Sun, 04 Apr 2010 03:29:41 -0700, sreenath wrote:

Hi,

I am using a rapid fixer sold in India be the name
"Agefix" The
instructions that come with the bottle just suggests a
dilution of 3-5
times for film.

I have been using the suggested dilution with no problem.

My question is the capacity of this diluted fixer. I kept
using the 1
liter for more than a year. Every time I do a film clip
test and observe
that film clears very quickly.

Is it possible for the fixer to clear the film clipping
but still be
unable to fix the film completely?

Are there any other tests for fixers?


Agefix is an Agfa product. With standard dilution, no
replenishment, 1
liter will fix 1 square meter of film before the fixer is
exhausted.
That's about 20 rolls of 36 exposure, 35mm film.

Here's a link to the Agfa film chemistry pdf. The Agefix
info is on page
12 of the document.

http://www.cri.ensmp.fr/~silber/photo/docs/films.pdf


Stef


The real test for fixer is the residual silver in the
emulsion. There are two simple tests. One is about a 2%
solution of sodium sulfide (not sulfite) the other is a 1:9
dilution of Kodak Rapid Selenium Toner. Either will tone the
remaining halides or silver complexes readily leaving a
stain. A drop or two of the solution is placed on _wetted_
film or paper and left for a couple of minutes, they rinsed
off. It should leave NO stain if the emulsion has been
completely fixed.
With any fixer the capacity can be much extended by
using two successive baths. This technique extends the
ability of the fixer to completely fix from four to ten
times. Instructions for the technique and for the test
solutions can be found in the _Kodak Black and White
Darkroom Data Book_ I don't know if this is still published
but old editions have the same information in them.
The problem is that an exhausted fixing bath will
continue to clear emulsions long after it has become too
exhausted to completely fix out all the silver halide. The
complexes left in the emulsion will change over time to a
form which can no longer be removed by re-fixing and will
eventually destroy the image.


--
Richard Knoppow
Los Angeles, CA, USA



  #3  
Old April 4th 10, 11:24 PM posted to rec.photo.darkroom
Toni Nikkanen
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Posts: 255
Default Capacity/life of rapid fixer


All of the above suggestions are great but being the lazy person I am,
I just use Agefix in 1+5 dilution in quantity of 1 litre, for 10 rolls
of film and then make a new one. I am probably wasteful but it's not
that expensive around here in 1.25 litre bottles, which makes 7.5
litres of fixer that lasts for 75 rolls of film. I don't even adjust
fixing times..

  #4  
Old April 6th 10, 03:56 PM posted to rec.photo.darkroom
Richard Knoppow
external usenet poster
 
Posts: 751
Default Capacity/life of rapid fixer


"sreenath" wrote in message
...
On Apr 5, 3:24 am, Toni Nikkanen
wrote:
All of the above suggestions are great but being the lazy
person I am,
I just use Agefix in 1+5 dilution in quantity of 1 litre,
for 10 rolls
of film and then make a new one. I am probably wasteful
but it's not
that expensive around here in 1.25 litre bottles, which
makes 7.5
litres of fixer that lasts for 75 rolls of film. I don't
even adjust
fixing times..


Hi,

Thanks for all the information and suggestions.

Hi, I mis-spelt the name as "Agefix". Actually it is
"Agifix"
When I searched on web for information, I thought it would
be similar
to Adefix of Agfa, but then was not sure.

The bottle says "Rapid fixer for X-Ray and graphic
industry". They
don't explicitly state it is for regular films.

It goes on to say : "Add 3.5 litres of water to the
contents ....."
meaning a total volume of working strength
solution of 4.5 litres. So , I am not sure of the actual
strength of
the working dilution.

I guess I will dump the fixer after about 20 rolls.

Thanks,
Sreenath


If you can manage to find a data sheet for this stuff
it would be worthwhile. X-Ray film has very thick emulsions,
some are coated on both sides. They are harder to fix out
that pictorial films so this fixer may be stronger than a
standard fixer. Evidently AGFA used the same trade name for
several fixers, the Agifix I am familiar with is a
non-hardening fixer for color work that is nearly neutral in
pH. That works fine for pictorial film and printing paper
except you can not use an acid stop bath with it.
A note: The potassium iodide test will show when there
is a certain amount of silver in the fixer but is not
quantitative. The test varies with the dilution of the test
solution. The only test which shows if the fixer is working
is to test the fixed emulsion for residual silver halide.
That is done with either a solution of sodium sulfide or a
1:9 dilution of KRST, as I mentioned in a previous post in
this thread. The iodide test may fail, that is, it may show
the fixer as being good when it is actually too diluted for
archival fixing. A two bath fixing method is a great help in
achieving permanent images and is economical because it
increases the capacity of the fixing bath by four to ten
times. The use of a sulfite wash aid such as Kodak Hypo
Clearing Agent will also help because it makes some not
quite completely fixed complexes soluble so they wash out.



--
Richard Knoppow
Los Angeles, CA, USA



  #5  
Old April 7th 10, 10:16 PM posted to rec.photo.darkroom
Richard Knoppow
external usenet poster
 
Posts: 751
Default Capacity/life of rapid fixer


"sreenath" wrote in message
...
On Apr 6, 7:56 pm, "Richard Knoppow"
wrote:
"sreenath" wrote in message

...



On Apr 5, 3:24 am, Toni Nikkanen
wrote:
All of the above suggestions are great but being the
lazy
person I am,

Are there any alternatives to sodium sulfide for this test
and in
general for toning etc? I had about 500 grams of this
stuff, and it
absorbed water from air. I had to dispose it off.

I would like to avoid having this chemical around because
of the smell
and its ability to fog photo emulsions.

I use two bath fixer made from hypo for paper and have no
confusion
there as to degree of fixation.
When I fix fiber paper I also use a sulfite wash aid.

thanks,
Sreenath


Kodak at one time recommended a 1:9 dilution of Kodak
Rapid Selenium Toner. This has low odor. I don't know how
easy it is to get now. Its used in the same way as the
sulfide test except that it must be used on well washed
films or prints since it may fail to stain if there is an
excess of hypo in the emulsion.
Ideally, neither test solution should leave any stain
if the emulsion is fully fixed.
Micheal Gudzinowicz posted some very complete
explainations of how fixer works to this group several years
ago. I think Google will still find them. They are worth
reading because they will give you a better understanding of
the limits on fixer capacity.
Clearing time is a dangerous criteria to use in judging
fixer capacity since partially exhaused fixer will "clear"
film long after it has reached the point where it is no
longer fixing out completely. Because there are no longer
enough free thiosulfate ions to completely convert the
halide to water soluble form mearly extending the fixing
time will not compensate for this.
I use Kodak Hypo Clearing Agent on both fiber paper and
on film. Because the emulsion on RC paper is so thin it
washes out to archival level very quickly without any
special treatment. The use of KHCA on it may actually wash
it too much.
The older ideas about archival washing were based on the
idea that NO thiosulfate whatsoever should remain in the
emulsion, however, about 1960 T.H.James of Kodak Research
Laboratories discovered that very small amounts of
thiosulfate remaining in the emulsion would stabilize the
image silver resulting is some resistance to oxidation. This
was such heresy that James was reluctant to publishe his
results until similar findings from Fuji's lab were
published. The discovery caused Kodak to revise its washing
recommendations. KHCA can wash down too far if its applied
for too long and subsequent washing is carried on for too
long. Current Kodak recommendations for KHCA and washing
times in general take cognizance of this. Its interesting
that a great many "drugstore photofinisher" snapshots have
survived because they were fixed OK but not overwashed where
materials given "archival" washing treatment but no toning
have developed the symptoms of oxidation, i.e., silvering of
the surface and staining of the image.
Toning is still the best protection. The Image
Permanence Institute currently recommends a polysulfide
toner like Kodak Brown Toner for this because it gives
uniform toning for partial toning. KRST, which used to be
the standard method was found not to be effective for
partial toning. It does, however, provide good protection if
some change in image density or color can be tolerated. The
recommendation is to use a dilution no weaker than 1:9 and
for not less than 3 minutes at room temperature for prints
and films.


--
Richard Knoppow
Los Angeles, CA, USA



  #6  
Old April 8th 10, 04:25 PM posted to rec.photo.darkroom
Peter Irwin
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Posts: 352
Default Capacity/life of rapid fixer

sreenath wrote:

Hi,

How long will b/w prints last if fixed and washed properly, but not
toned?


I've seen a lot of early 20th century family photos which have survived
just fine with normal storage in photo albums and envelopes. There are
no guarantees (I think pollution can be a big variable), but there is
nothing particularly unlikely about an untoned black and white print
lasting a hundred years or more.

Peter.
--



  #7  
Old April 9th 10, 07:36 AM posted to rec.photo.darkroom
Richard Knoppow
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Posts: 751
Default Capacity/life of rapid fixer


"Peter Irwin" wrote in message
...
sreenath wrote:

Hi,

How long will b/w prints last if fixed and washed
properly, but not
toned?


I've seen a lot of early 20th century family photos which
have survived
just fine with normal storage in photo albums and
envelopes. There are
no guarantees (I think pollution can be a big variable),
but there is
nothing particularly unlikely about an untoned black and
white print
lasting a hundred years or more.

Peter.
--


That seems to be the case. If the films or prints are
fixed thoroughly they should be washed according to Kodak
recommendations. Since Kodak no longer makes B&W paper the
usual recommendation is to wash single weight fiber paper
for an hour and double weight for two hours in running
water. If a sulfite wash aid is used 20 minutes is enough
for single weight and half an hour for double weight. Since
the washing is a slow process longer wash times are OK
provided they are not extremely extended. The above is for
water at about 68F (20C), washing is faster in warmer water.
When a sulfite wash aid is used even quite cold water is
effective.
Washing is faster when a non-hardening fixing bath is
used since the usual white alum hardener acts as a mordant
for the thiosulfate when it is acid. By treating film or
paper with a mild alkali the mordanting is eliminated.
However, if the pH is much more than 7 (neutral) the
hardening is also eliminated. Kodak Hypo Clearing Agent is
buffered to neutral so that the hardening is preserved. The
alkali also serves to affect the electrical charges in the
gelatin so as to make it repel the thiosulfate ions where
when it is acid it attracts them.
Film washes out much faster than fiber paper because
the support does not absorb any hypo. For untreated film
fixed in a normal acid hardening fixer half an hour is
enough. If treated in KHCA five minutes is sufficient.
RC paper washes out in four minutes after normal acid
fixer even when no wash aid is used and wash aid is not
recommended by Kodak unless one is experiencing staining
problems when toning.
Polysulfide toner is the one recommended currently
because it provides protection to all densities even when
only partial toning is done. KRST tones the finer grains
found in the high density parts of the image before it tones
the coarser ones so that when highly diluted (1:19) KHCA is
used as formerly recommended, the low densites may not be
protected. If toning is carried out far enough it protects
all densities.
I don't know of another toner that can be used for
partial toning and provide full protection against oxidation
and sulfiding. The standard for microfilm is gold toning. It
is quite effective and causes relatively little change in
tone or density on cold or neutral tone paper. Its drawback
is that its expensive. Gold will form fairly vivid blue
images on very warm tone paper but on neutral or cold tone
paper the color shift is small to none. Its useful where one
finds a paper a bit green.
Polysulfide toner is easy to make. Kodak gives a formula
as Kodak T-8. According to the IPI this is as effective as
Kodak Brown Toner for image protection. However, if you
can't obtain polysulfide that isn't very useful to you.
The theory about the small residue of thiosulfate is
that it causes a slight amount of surface sulfiding of the
silver crystals. Silver sulfide is very stable so once a
layer of sulfide forms it goes no further and is also
passive as far as oxidation is concerned. The problem is
that there is no definite information about wash times, etc.
Another anti-oxidation treatment involves the use of a
chemical like thiocyanate in highly diluted form. This is
what AGFA Sistan was. While Sistan was not as effective as
toning it does have the advantage of not causing any change
to the image color, density, or structure. The latter is of
little consequence in pictorial photography but can be
critical for microfilm.
FWIW, _any_ sulfiding toner will fully protect images if
carried out to completion, however all will change the image
color. KRST will provide full protection according to
Dr.Douglas Nishimura of IPI if used at a dilution of no
greater than 1:9 and for not less than 3 minutes at 68F.
Gold toners are very effective.
Other toners such as iron, copper, uranium, etc, form
imgages which are _more_ vulnerable than the original silver
image although they may produce attractive colors.
BTW, it has become much more difficult to obtain
photographic chemicals even here in the USA.


--
Richard Knoppow
Los Angeles, CA, USA



  #8  
Old April 9th 10, 04:52 PM posted to rec.photo.darkroom
Richard Knoppow
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Posts: 751
Default Capacity/life of rapid fixer


"Richard Knoppow" wrote in message
...

"Peter Irwin" wrote in message
...
sreenath wrote:

Hi,

How long will b/w prints last if fixed and washed
properly, but not
toned?
found in the high density parts of the image before it
tones

the coarser ones so that when highly diluted (1:19) KHCA
is

^^^^^^^^^^^^^^
Mis-typed, should read KRST i.e., Kodak Rapid Selenium
Toner


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



 




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