question about fixing hp5

Actually I meant both, my original reply was intended for the poster
asking about using hypo check to monitor his fixer and using a two bath
fixing method for film. These type of hypo test solutions can only tell
you when your fixer has gone bad.

ST-1 will create a stain on the emulsion that can be visually evaluated,
it's a measure of how we the user is fixing his film, hence the advice
to use it only on a film leader or blank frame snipped form the roll to
be tested.

wrote:
darkroommike wrote:
Sorry meant hypo check.


HT-1 is a hypo check. So is HT-2. The two are used
to check for thorough washing out of the hypo. You have
in mind FT-1 which is the iodide test of the Fixer. ST-1 is
a test for silver left in the emulsion. Use ST-1 along with
FT-1 to be more sure of complete fixing. Dan

"darkroommike" wrote in message
...
Actually I meant both, my original reply was intended for
the poster asking about using hypo check to monitor his
fixer and using a two bath fixing method for film. These
type of hypo test solutions can only tell you when your
fixer has gone bad.

ST-1 will create a stain on the emulsion that can be
visually evaluated, it's a measure of how we the user is
fixing his film, hence the advice to use it only on a film
leader or blank frame snipped form the roll to be tested.

wrote:
darkroommike wrote:
Sorry meant hypo check.


HT-1 is a hypo check. So is HT-2. The two are used
to check for thorough washing out of the hypo. You have
in mind FT-1 which is the iodide test of the Fixer. ST-1
is
a test for silver left in the emulsion. Use ST-1 along
with
FT-1 to be more sure of complete fixing. Dan


Kodak HT-1 is an old test for residual hypo which is no
longer considered adequate. It employs a Potassium
permangante solution into which water from the negative or
print is allowed to drain. If a stain develops its in
indication of hypo in the water. Unfortunately, this test
does not indicate hypo held in the emulsion or support. It
is quite possible for HT-1 to indicate complete washing when
there is still thiosulfate and thiousulfate complexes bound
up in the gelatin.
A more reliable test is Kodak HT-2, this uses a solution
of preserved Silver Nitrate. This test solution is placed on
the emulsion and produces a stain of Silver Sulfide if there
is thiosulfate present. HT-2 is a very easy to use test but
is limited in its sensitivity. The current test for washing
approved for use on microfilm is the Methylene Blue test.
However, this is not trivial to conduct so the Silver
Nitrate test remains the best choice for home darkrooms.
Measuring the degree of fixation is best done with a
sulfiding toner. The Kodak Sodium Sulfide test will give a
direct indication of residual silver and silver complexes
from fixing. With care, a 1:9 dilution of Kodak Rapid
Selenium Toner can also be used, however, the emulsion must
be well washed because the presense of Thiosulfate will
cause the test to fail. Testing for residual silver in the
fixed material is the best test because it is a direct test
of the degree of fixing. It is the residual silver in the
emulsion which will cause eventual image degradation.
The Potassium Iodide test will give an indication of
dissolved silver in the fixing bath. However, it is not
quantitative and the reaction varies with the dilution of
the test solution. Measuring clearing time will also give an
indication of the amount of dissolved silver. However,
neither is as reliable as testing for residual silver in the
emulsion.
Fixing is not a simple reaction. It is rather a series of
progressive reactions which eventually convert the insoluble
Silver Halide in suspension in the emulsion to a water
soluble form which will wash out. Between these two
conditions the Halide becomes progressively more soluble but
incomplete fixing will leave some remainder of material
which is either insoluble or very tighly bound to the image
silver or the gelatin. It is quite possible for a fixing
bath which is capable of clearing the emulsion, that is,
making it free of the cloudy appearance of unfixed film, not
to be able to complete the fixing process to the point where
all the residual halide is converted to soluble form. The
rule of thumb is to fix for twice the clearing time but,
eventually, the fixing bath will not be able to complete the
fixing process in any amount of time.
Another old rule of thumb is to discard the fixer when
clearing time is doubled. This is probably satsifactory for
commercial permanence ( 10 - 20 years) but is not so for
archival permanence.
It takes about 3 Thiosulfate ions to convert one ion of
Silver halide to the fully soluble form. As emulsion is
fixed more and more Thiosulfate ions combine with the halide
in the emulsion to become silver-thiosulfate complexes. At
some point there will not be enough ions available to
complete the fixing process. Obviously, there are will be
more ions available in a more concentrated solution, so the
capacity of the solution per unit volume will increase with
concentration. Very early research at Kodak Labs produced a
misleading result which suggested that fixing rate did not
increase beyond a critical concentration. It was found later
that this was due to testing with dry emulsion. When a
wetted emulsion was used the fixing rate continued to
increase with concentration with no indication of an optimum
concentration. That is why it is important to used wetted
(saturated) film when testing for clearing time.
It is the relation between free thiosulfate ions and
concentration that makes me very skeptacle of the use of
highly diluted single use fixing. Even though the fixer is
"fresh" the dilution may reduce the amount of thiosulfate
ions to the point where it is no better than a well used
bath.
The capacity of a single fixing bath to fix to archival
standards is very limited. Ilford states its about 10 8x10
prints per _gallon_. By using two successive baths the
capacity is increased by 4 to 10 times. This is a great
economy beside insuring archival fixing. The use of a
Sulfite wash aid also increases the capacity somewhat
because it can break the chemical bond between some
incompletely converted complexes and the emulsion, allowing
them to be washed out.
Note that counting the amount of film or paper processed
in a fixing bath can be misleading because the amount of
residual silver will vary with the nature of the image. The
more halide converted to metallic silver by development the
less there will be for the fixer to work on. So dense
negatives leave less halide than thin ones. The capacity
will also be affected by the thickness of the emulsion and
the nature of the halide.
Fixing baths are also affected by Iodides dissolved from
the emulsion. Most film is rich in Silver Iodide. The Iodide
ions leached into the fixing bath tend to retard fixing. In
a two bath system most of the Iodide will have come out in
the first bath leaving the second one unaffected. Iodide
does not reduce the ability of the fixing bath to convert
halide but does slow it down.
Ammonium thiosulfate is less sensitive to dissolved
Iodides than Sodium thiosulfate fixer, so its use is
suggested for high Iodide emulsions like Kodak T-Max and
Tri-X films. Again, the use of a two bath system makes this
difference less significant.

Kodak Residual Silver Test Solution ST-1
Water 100.0 ml
Sodium Sulfide, anhydrous 2.0 grams

Store in a small stoppered bottle for no more than 3 months.
To use take one part stock and 9 parts water. Place a few
drops of the diluted solution on a clear part of a negative
or print. Allow to stand about 2 to 3 minutes and rinse or
blot off. There should be no stain left.
The working solution lasts about a week.
Because any stain formed is permanent its best when
testing prints to process a scrap of the paper along with
the prints and use that for testing.

Completeness of washing can be tested using the Silver
Nitrate test Kodak HT-2

Kodak HT-2 Residual Hypo Test
Water (distilled) 750.0 ml
Acetic Acid, 28% 125.0 ml
Silver Nitrate, crystals 7.5 grams
Water to make 1.0 liter

The use of distilled water is important. Any halide, such as
chlorine, in the water will react with the Silver Nitrate
producing some silver halide which will precipitate. Make
sure the Acetic Acid is also diluted with distilled water.
For use place a drop or two on a clear area of the film or
paper and allow to stand for about 2 minutes, then blot off.
There should be no more than a very slight yellow stain.
Kodak sells a "Hypo Estimator" also published in the _Kodak
Black-and-White Darkroom Data Book_. This can be used to
estimate the amount of residual hypo. The above is a
lifetime supply so I suggest making up about 100 ml. The
life of the soluion is about 6 months. Note that the stain
will increase wtih time unless fixed. A more elaborate
version of this test, which fixes the stain using Sodium
Chloride, can be used for densitometric measurement.
However, for very sensitive work the Methylene Blue method
is preferred. This test is, however, suitable for evaluation
of home darkroom washing methods.


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

Richard Knoppow wrote:

Completeness of washing can be tested using the Silver
Nitrate test Kodak HT-2

Kodak HT-2 Residual Hypo Test
Water (distilled) 750.0 ml
Acetic Acid, 28% 125.0 ml
Silver Nitrate, crystals 7.5 grams
Water to make 1.0 liter


Ilford's silver nitrate test for the sulfur which is bound
to the sulfite in thiosulfate is not the same as Kodak's. The
strength is 1% and uses no acetic acid. I wonder why or why
not the acetic acid? I'll be testing both formulas. Do you
think Heinz' 5% synthetic Vinegar will do? It's distilled.


For use place a drop or two on a clear area of the film or
paper and allow to stand for about 2 minutes, then blot off.
There should be no more than a very slight yellow stain.


The test is to be conducted in subdued light. Although it
is the nitrate of silver it will still darken on exposure. Also, I
suspect that spot-test picks up minute amounts of air born
sulfur and very slowly darkens.
Martin Reed mentions a Zero visible stain on whole sheets
being a fully effective practical test. The context is archival print
washers. Whole sheet tests will reveal uneven washing. That
problem I do not have. Still Water Diffusion washes are not
plagued by uneven currents and eddy formation. Dan

On 27 Jul 2006 17:39:16 -0700,
wrote:

Do you
think Heinz' 5% synthetic Vinegar will do? It's distilled.


July 28, 2006, from Lloyd Erlick,

Five per cent of what they sell in the
container is acetic acid. The rest is water.
It seems very doubtful that distilled water
would be used. Most likely it is pure,
filtered, delicious municipal tap water
delivered to the factory by traditional
underground pipes.

I'd be surprised if the impurity of the water
caused any problems in the darkroom, although
I use distilled water a lot. I even use it to
prepare fixer.

Ascetic acid is a distilled product. In my
neighbourhood, the cheapest source of acetic
acid is farms in Quebec and Ontario. Apples
unsuitable for sale as eating or cooking
apples (think how many apples fall off the
trees or just look unattractive ...) end up
used for acid production. Glacial acetic is
made by distillation.

Is vinegar such a profitable thing that a
synthetic form is viable? Or could it be
cheaper to make that way?

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
website: www.heylloyd.com
telephone: 416-686-0326
email:
________________________________
--

wrote in message
oups.com...
Richard Knoppow wrote:

Completeness of washing can be tested using the Silver
Nitrate test Kodak HT-2

Kodak HT-2 Residual Hypo Test
Water (distilled) 750.0 ml
Acetic Acid, 28% 125.0 ml
Silver Nitrate, crystals 7.5 grams
Water to make 1.0 liter


Ilford's silver nitrate test for the sulfur which is
bound
to the sulfite in thiosulfate is not the same as Kodak's.
The
strength is 1% and uses no acetic acid. I wonder why or
why
not the acetic acid? I'll be testing both formulas. Do you
think Heinz' 5% synthetic Vinegar will do? It's distilled.


For use place a drop or two on a clear area of the film
or
paper and allow to stand for about 2 minutes, then blot
off.
There should be no more than a very slight yellow stain.


The test is to be conducted in subdued light. Although
it
is the nitrate of silver it will still darken on exposure.
Also, I
suspect that spot-test picks up minute amounts of air born
sulfur and very slowly darkens.
Martin Reed mentions a Zero visible stain on whole
sheets
being a fully effective practical test. The context is
archival print
washers. Whole sheet tests will reveal uneven washing.
That
problem I do not have. Still Water Diffusion washes are
not
plagued by uneven currents and eddy formation. Dan


Unless the full test procedure is used (I have it
somewhere) the stain will continue to darken with time. The
simple version of the test is meant to be interpreted at the
moment (I almost said on the spot) since it won't be valid
later.
I am not sure why the Acetic acid is included, I thought
it was a preservative for the silver nitrate but it may
serve some other purpose.
Once you establish a wash routine that is satisfactory
the test does not have to be run very often. It can be used
on whole prints to test for uniformity of washing. Some so
called archival washers do not produce enough turbulance to
wash near the edges of prints. This test will show if that
kind of problem exists.
I disagree about washing by diffusion in still water. It
is very slow and the water will eventually reach equilibrium
with the emulsion unless the volume is very large. Washing
of the emulsion _is_ a diffusion process, however, the rate
of diffusion depends on the ratio of the concentration of
the thiosulfate in the emulsion to the concentration in the
water. The process is fastest when there is a continuous
supply of fresh water at the surface of the emulsion. Since
the washing takes place in a very thin layer near the
surface its possible to do it with relatively little water
by providing a thin layer of water wity high rate of flow at
the surface. Most archival washers have too much volume and
don't change the water fast enough. Adequate washing can be
done using successive baths of fresh water but the water
must be agitated continuously to remove the thiosulfate
diffusing out of the emulsion. Both Kodak and Ilford have
routines for successive bath washing; Kodak's uses equal
intervals, Ilford uses intervals which start short and get
longer. Both work but the Ilford method probably uses less
water so is the choice where water conservation is
important.
The support of fiber paper does not wash by a strictly
diffusion process. Some of the thiosulfate is held by
frictional forces in the fiber structure of the paper. The
use of a wash aid will help displace it but is far less
effective on the support than it is on the emulsion. Rapid
flow of water is necessary to dislodge the thiosulfate from
the support. This is why the wash times for fiber is so much
longer than for RC or film even when wash aid is used.
BTW, if the material being washed is vertical in still
water there will probably be a convection current generated
by the slightly higher density thiosulfate laden water at
the surface. The thiosulfate does not sink to the bottom as
some old books state (this idea did NOT originate with Fred
Picker) but rather forms a cloud of ever decreasing
concentration as it diffuses out into the body of the water.
Since the water at the surface IS a little more dense it
will tend to move downwards as it diffuses further creating
a very slight convection current. This is probably only of
academic interest but it is the mechanism, for instance,
which causes bromide streaks on sheet film which is
developed in tanks with inadequate agitation.


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

Lloyd Erlick wrote:

wrote:

Do you
think Heinz' 5% synthetic Vinegar will do? It's distilled.

Is vinegar such a profitable thing that a
synthetic form is viable? Or could it be
cheaper to make that way?
________________________________
Lloyd Erlick Portraits, Toronto.
website: www.heylloyd.com
telephone: 416-686-0326
email:
________________________________


White vinegar. Actually clear as crystal. The apple
has a brownish hue. Have you Heinz north of the border?
IIRC, they both claim to be distilled. I'd guess to make
strength. Dan

Richard Knoppow wrote:

I disagree about washing by diffusion in still water. It
is very slow and the water will eventually reach equilibrium
with the emulsion unless the volume is very large.


It is slow. I allow hours. A last soak can be over-night.
I think you have an incorrect picture in mind. Consider:
After the fix there is a rinse a hca and again a rinse. Even
with the usual strength fixer very little fix is left in the paper
after that routine.
The washes follow using hydrophobic separators
bottom and top of stack and one twixt each print. With
the new and much better separators I began using very
recently as little as 1/4 liter of water per 8x10 will do.

With three transfers, 4 soaks, a total of 1 liter of water
is needed per 8x10. Allowing for the bottom 1/4 each wash
and 4 prints; that works out to 1 and 1/4 liter of water
used per 8x10 or a total of 5 liters for the four. Dan

wrote in message

It is slow. I allow hours. A last soak can be over-night.
... three transfers, 4 soaks, a total of 1 liter of water

But it would seem that circulating the water would improve/
speed the wash. If they soak the whole print is as if in
the stagnant zone of a print washer.

I take it the goal, though, is to minimize water usage?


--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics, Photonics, Informatics.
Remove blanks to reply: n o lindan at ix . netcom . com
f-Stop enlarging timers: http://www.nolindan.com/da/fstop/

Nicholas O. Lindan wrote:

wrote in message

It is slow. I allow hours. A last soak can be over-night.
... three transfers, 4 soaks, a total of 1 liter of water

But it would seem that circulating the water would improve/
speed the wash. If they soak the whole print is as if in
the stagnant zone of a print washer.

I take it the goal, though, is to minimize water usage?

Nicholas O. Lindan, Cleveland, Ohio


Totaly stagnant. At transfer from first to second tray they
do experience a little agitation. My old separators were squeese
dried then stored moist in a caped container ready for use. The new
ones will be press dried in the tray then rolled or folded and moist
stored. I've measured the water in and out. Some 90% plus of
the water simply runs out of the tray and separators. Near
100% with hand pressure and the separators in the tray.
I've very hard water so the less distilled I have to lug the better.
A second reason is space saving. Although space for two trays are
needed at transfer only one need take up space while the wash
proceeds. A third reason is no need to plumb. A fourth reason
is no outlay of $$$. A fith reason is the lack of confidence.
That "stagnant zone of a print washer" comment you've
made is just one example. From bubble trouble to
leaks to clean-up, etc.
I've some exhaustive testing to do with the my new separators.
That's why my interest in the ST-1 and HT-2 tests. I need a for-
sure proceedure if I'll ever make it through the back-log of
printing I've to do.
As Mr. Knoppow has put it, the fixer diffuses out of the
emulsion and into the body of water. A few changes of water
are needed. The process is slow. Dan

On 28 Jul 2006 15:52:39 -0700,
wrote:

White vinegar. Actually clear as crystal. The apple
has a brownish hue. Have you Heinz north of the border?
IIRC, they both claim to be distilled. I'd guess to make
strength. Dan


July 29, 2006, from Lloyd Erlick,

There are all fifty seven varieties of Heinz;
only Patricia is missing.

Rotten apples eventually get to acetic acid,
I suppose. Distilling it takes out the
undesirables. Sounds like it should be cheap.

regards,
--le