alternatives for ammonium thiosulfate?
Klaus Schmaranz
Ammonium thiosulfate is quite difficult to get (and expensive!)
because it's quite unstable... sofar, so good...
Is there any alternative to be used for a fixer that will be capable
of fully fixing modern emulsions (such as rapid fixer)? Sodium
thiosulfate doesn't do a perfect job on them, at least not if they
contain silver-iodide.
BTW - is there any source where I can find out which films and papers
need ammonium thiosulfate because of the iodide, and which don't?
Thanks,
Klaus.
Lloyd Erlick
jul901 from Lloyd Elick,
I would like to see corroboration for the statement
that sodium thiosulfate is an inappropriate fixing
material for 'modern emulsions.'
I have been using a simple, cheap and easy to mix
sodium thiosulfate based fix for my Kodak T-Max 400
(TMY) films for several years. If there is any problem
with my negs, I have yet to detect it.
The fix I use is Ansel Adams' 'plain fix', which he
describes in his book, "The Print". I find it excellent
for both prints and film; in fact, I use it for all my
fixing needs. (Separate batches for film and prints!)
I use this fix two-bath style for film, seven minutes
in each. I absolutely never see any color tinge on my
TMY negs.
I usually develop film in runs of ten rolls (I use 120
format film), and I find three liters of solution cover
my ten rolls very nicely in four-inch diameter
cylinders (two rolls on each of five Jobo 1501
developing reels). My two containers of three liters
each very nicely fix fifty rolls of film over a period
of weeks.
I don't bother changing my second fix to first fix when
it comes time to dump. I just mix two fresh ones; it's
pretty cheap stuff and my negatives are the primary and
irreplacable step in the long march to a print (and a
living...)
It's undeniably true that sodium thiosulfate based fix
is exhausted (or at least rendered inoperative) more
quickly by 'modern' film. I think I'd be able to fix a
lot more than fifty rolls of old-tech materials with a
total of six liters of my fix. But I hate the smell of
rapid fix, and I do not wish to pay for it. I also do
not want to drag it home from the store, and frankly
its vastly greater capacity just means I'll be wasting
some of it a little later. My rate of film usage fits
nicely with the lesser capacity of sodium thiosulfate
based fix.
The slower action and lesser capacity of sodium
thiosulfate based fix are positive and attractive
features to me. They are not indications of
inappropriateness.
I would like to see proper citation from the literature
or statements from recognized experts (such as some of
the ones who read this newsgroup...) to support the
contention that a sodium thiosulfate fix is either
inappropriate, inadequate, or actively harmful when
processing 'modern' emulsions like TMY.
regards,
--le
-------------------------------------
Lloyd Erlick,
357 Richmond Street West,
Toronto M5V 1X3 Canada.
---
voice 416-596-8751
ll...@the-wire.com
http://www.heylloyd.com
-------------------------------------
Francis A. Miniter
While I don't have it in front of me, I recall reading the statement in
Anchell and Troop, The Film Developing Cookbook. I will look up the
reference tonight and follow up with you on it. I seem also to recall
seeing it earlier than that book in an article in Photo Techniques USA,
but that will be harder to find, I think.
As I sit here now, I do not recall that much detail was given as to how
these conclusions were reached. But I do think that Klaus is right about
it being related to the proportion of silver iodide in the emulsion.
Perhaps Dr. Gudzincowicz can give us the chemical side of the problem.
In any case, I have for the last few years, as a result, been using
ammonium thiosulfate for my films, reserving sodium thiosulfate for my
papers.
Francis A. Miniter
Lloyd Erlick wrote:
> Klaus Schmaranz <ksc...@iicm.edu> wrote:
>
> >Hi,
> ><snip>
> >Is there any alternative to be used for a fixer that will be capable
> >of fully fixing modern emulsions (such as rapid fixer)? Sodium
> >thiosulfate doesn't do a perfect job on them, at least not if they
> >contain silver-iodide.
> <snip>
> >Thanks,
> > Klaus.
>
> jul901 from Lloyd Elick,
>
> I would like to see corroboration for the statement
> that sodium thiosulfate is an inappropriate fixing
> material for 'modern emulsions.'
> <snip>
Nicholas O. Lindan
>
> Ammonium thiosulfate is quite difficult to get (and expensive!)
Not on this side of the great puddle. It is about $12/gallon from a
photo supplier. You can also purchase this chemical for agricultural
uses where it is used as a fertilizer and plant growth regulator.
> because it's quite unstable...
It is? Seems more stable than sodium thiosulfate to me.
There should be an increase in ammonium thiosulfate production as it
is being touted as way to cut use of methyl bromide in agriculture.
On the flip side, ammonia production is from natural gas and the price
of gas (as purchased for this purpose) has increased some 8-fold.
--
Nicholas O. Lindan, Cleveland, Ohio noli...@ix.netcom.com
Technical Management Consulting & Engineering Services:
New Product Development; Electrical Engineering;
Software, System and Circuit Design. Oh, & Photography
Klaus Schmaranz
Nicholas> Not on this side of the great puddle. It is about $12/gallon from a
Nicholas> photo supplier. You can also purchase this chemical for agricultural
Nicholas> uses where it is used as a fertilizer and plant growth regulator.
>> because it's quite unstable...
Nicholas> It is? Seems more stable than sodium thiosulfate to me.
Hmmmm.... interesting... my chemical supplier here has basically
everything you could possibly want, and the catalog of raw chemicals
available is a really thick book. I didn't find ammonium thiosulfate
listed there (sodium thiosulfate is available...), so I asked. The
answer was:
Ammonium thiosulfate is very unstable, so you have to place your
order, and if there are enough orders they make a fresh
batch. Needless to mention what this costs. Could it be that the guy
told me something wrong?
Could it be that it is not listed as ammonium thiosulfate but as
whatever liquid under a different name????
Klaus.
Klaus Schmaranz
Lloyd> I would like to see corroboration for the statement
Lloyd> that sodium thiosulfate is an inappropriate fixing
Lloyd> material for 'modern emulsions.'
Anchell / Troop have this statement in the "Film Developing Cookbook"
and it was also discussed here in this group not too long ago. The
problem that was mentioned was that modern emulsions contain a certain
amount of silver iodide and that silver iodide takes extremely long to
be fixed in sodium thiosulfate. I'm not good enough in chemistry to be
able to tell exactly what the problem with the iodide is, maybe
one of the real gurus here could comment on this.
Klaus.
Michael A. Covington
with a thiosulfate compound? That is, you don't start with solid ammonium
thiosulfate.
Richard Knoppow
Ammonium thiosulfate in powder form is rather unstable. In liquid
form its quite stable. So, rapid fixers are put up as liquid
concentrates.
Virtually any fixer formula for sodium thiosulfate can be made into
a rapid fixer by substituting ammonium thisulfate for the sodium salt
using the amount for the anhydrous form of the sodium salt.
One can also make a rapid fixer by adding ammonium chloride or
ammonium sulfate to a sodium thiosulfate fixer. The ammonium sulfate
is suggested when stainless steel tanks are to used since the chloride
formula will corrode them. An example is Kodak F-7 and F-9
Kodak F-7
Water, at 125F (see note below) 600.0 ml
sodium thiosulfate, crystals 360.0 grams
Ammonium Chloride 50.0 grams
Sodium Sulfite, anhydrous 15.0 grams
Acetic Acid, 28% 48.0 ml
Boric Acid, crystals 7.5 grams
Potassium aluminum sulfate 15.0 grams
Water to make 1.0 liter
F-9 is the same except for substituting
Ammonium sulfate 60.0 grams
for the ammonium Chloride above.
Note: When anhydrous sodium thiosulfate is used the amount should be
reduced to 230 grams and the water temperature should not be over 90F.
Ammonium thiosulfate fixers are less sensitive to soluble iodide
from fast emulsions. Sodium thiosulfate fixing baths are slowed down
by accumulated iodide but continue to fix the emulsion, they simply
need more time.
The use of a two bath fixing system eliminates to a great extent the
problem of accumulated iodide since nearly all of it comes out in the
first bath, leaving the second bath working at full speed.
Two bath fixing has the same advantage for rapid fixers that it does
for sodium fixers, namely the capacity for archival fixing is extended
by four to ten times and the relatively fresh second bath assures
complete solublization of the silver complexes.
The rapid fixers made by adding ammonia salt to a sodium fixer are
not quite the same as rapid fixers made with ammonium thiosulfate.
They are not quite as rapid.
As far as what types of films and paper have silver iodide in them,
all reasonably fast films are made with silver iodide. That means even
slow pictorial films like the late, lamented Agfa Agfapan-25. Faster
films, like Tri-X have an abundance of iodide, and the newer tabular
grain films also have a lot. Kodak recommends longer fixing times for
Tri-X as they do for T-Max films. Both can be fixed in sodium
thiosulfate fixers, provided enough time is alloted for complete
fixing.
The old rule of thumb is to allow double the clearing time for
complete fixing. You will find the clearing time for T-Max nearly
twice that for a film like Plus-X or Verichrome Pan. Some recommend
fixing T-Max for three times the clearing time. I think this is
unnecessary when a two bath fixer is used.
Its possible that some paper has silver iodide in it but I don't
know specifically which ones. Traditionally, paper is made with silver
chloride, silver bromide, or a mixture of the two. For the most part
the extra sensitivity given by siler iodide is not necessary for
paper. Most paper emulsions will fix out in a minute in fresh sodium
thiosulfate fixer when the print is fixed alone. Much longer fixing
times have traditionally been recommended to compensate for the use of
partially exhausted fixer and the fixing of many prints together,
preventing adequate access of fresh fixer solution to the surface.
Fresh film strength rapid fixer will fix out most paper emulsions in
30 seconds. This is the basis of the Ilford archival processing
method. Its purpose is to fix out the paper quickly enough to prevent
substantial adsorption of the fixer to the paper fibers.
Clearing time for film can be observed directly. A clip of the
unprocessed film is soaked in water for a few minutes and placed in
the fixer. Agitate it gently and measure the time until it becomes
transparent. Fixing time is generally twice the clearing time. The
reason for soaking the film first is that wet film fixes at a slightly
different rate than dry film. When dry the emulsion must swell first
for the solution to fully penetrate it. In practice, the film is
wetted and swollen when introduced into the fixer.
Please not that partially exhaused fixer can still clear the film,
but, if there are not enough thiosulfate ions left, it can not
complete the somewhat complex reaction that results in the reaction
products being soluble in water so they will wash out.
The two bath system insures these reactions will be completed and
the reaction products will wash out.
Any silver complex left in the emulsion will eventually decompose
and attack the image. Once the film has dried these reaction products
begin to change, so that even subsequent fixing in fresh fixer may not
make incompletely fixed film or paper permanent.
This is much more than I intended to write. I hope it is helpful
rather than confusing.
To summarize:
Conventional sodium thiosulfate fixer is suitable for high iodide
films, providing a two bath fixing system is used.
All pictorial films have some silver iodide, but fast films have
more.
Some paper may have silver iodide but it is not traditionally used in
paper emulsions.
A kind of rapid fixer can be made without ammonium thiosulfate by
adding ammonium salts to conventional fixer.
Even rapid fixer is not a gurantee of complete, archival, fixing. A
two bath system with either type of fixer is a large help.
I will add finally that the use of a fixing bath test solution is
helpful in keeping track of fixing bath condition. The formula and
instructions for Kodak FT-1 is given in the _Kodak Black-and -White
Darkroom Dataguide_. I prefer this to the prepared Edwal Hypo Check
because the Kodak formula is of known strength and specific dilution
is given for testing various types of baths.
The same book has the formula for the residual silver test ST-1,
whichis a 2% solution of Sodium Sulfide. A 1:9 dilution of Kodak Rapid
Selenium Toner can also be used to test for residual halide. A few
drops are applied to the wet emulsion and allowed to work for about
two minutes. The emulsion is then blotted and examined for any stain.
Either solution will stain silver halide. There should be NO stain if
the film or paper is completely fixed.
Enough !
---
Richard Knoppow
Los Angeles, Ca.
dick...@ix.netcom.com
Francis A. Miniter
Francis A. Miniter
Nicholas O. Lindan
>
> Another keeper with Richard's name on it!
Yup. The thread starts in Austria at 11 am (5 am EST).
It percolates across the US, various folks tut-tutting and making spurious
remarks till Richard gets home from work, and then: the answer -> you want
the stuff as a liquid, the solid form is indeed unstable and expensive as
the chemical supplier in Austria said......
It all seems a bit like the opening scene in Terry Gallium's movie
"Brazil" -- Harry Tuttle rappels into a scene of utter hopelessness,
red tape and technologic collapse, pops off a panel to an underworld
of pipes steam and sparks, reaches in and magically makes everything
right again.
--
Nicholas O. Lindan, Cleveland, Ohio noli...@ix.netcom.com
Consulting Engineer: Electronics, Informatics, Photonics.
Klaus Schmaranz
...one more answer from the source of wisdom! It has been said several
times by several people here, but I have to say it again:
Richard, MANY THANKS for all the effort you put in your answers. You
are indeed an invaluable source of knowledge and you saved many people
lots of time and prevented them from making mistakes and from several
disappoointments.
Maybe.... could we talk you into writing a book???? There are so many
things that you know and that are not collected anywhere in a single
book, so I'm sure this would be a must-have for all people having to
do with a darkroom....
Klaus.
>>>>> "Richard" == Richard Knoppow <dick...@ix.netcom.com> writes:
Richard> Ammonium thiosulfate in powder form is rather unstable. In liquid
Richard> form its quite stable. So, rapid fixers are put up as liquid
Richard> concentrates.
--
-----------------------------------------------------------------------------
Dipl. Ing. Dr. techn. Klaus Schmaranz
Institute for Information Processing and Computer Supported New Media (IICM)
Graz University of Technology, Graz/Austria/Europe/Earth/Milky-Way/Universe
email: ksc...@iicm.edu, phone: +43/316/873-5611, fax: +43-316-873-5699
-----------------------------------------------------------------------------
Do you know the Dinopolis middleware project? Visit http://www.dinopolis.org
Colin DeWolfe
Colin
gordon....@live.ca
Jean-David Beyer
is faster than F-5.
Water 600ml Hot water
Sodium Thiosulfate 360gr crystalline or 230gr anhydrous
Ammonium sulfate 60gr
Sodium Sulfite (anhydrous) 15gr
Acetic Acid 28% 48ml
Boric Acid 7.5gr
Potassium Alum (fine dodecahydrated) 15gr Do not use anhydrous
Cold water to make 1000ml
It is a hardening fixer. If you do not want hardening, you could reduce
or omit the Potassium Alum.
I prefer F-6 fixer for most things.
Water, about 50 Celsius (125° F.) 600 ml
Sodium Thiosulfate (Hypo) 240 g
Sodium Sulfite, desiccated 15 g
Acetic Acid, 28%; 48 ml
Kodalk 15 g
Potassium Alum 15 g
Cold water to make 1 liter
Here, too, you can omit the potassium alum if you do not need hardening.
--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key:166D840A 0C610C8B Registered Machine 1935521.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 10:10:01 up 17 days, 12:31, 2 users, load average: 4.23, 4.23, 4.26
Richard Knoppow
"Jean-David Beyer" <jeand...@verizon.net> wrote in message
news:l6l8g...@news4.newsguy.com...
Water, about 125F (50C)......................600.0 ml
Sodium Thiosulfate, crystalline..............360.0 grams
Ammonium Chloride.............................50.0 grams
Sodium sulfite, desiccated....................15.0 grams
Acetic acid, 28%..............................48.0 grams
Boric Acid, crystalline....................... 7.5 grams
Potassium alum................................15.0 grams
Water to make..................................1.0 liter
As with the other formulas the alum can be left out and
probably the acid too if you don't want a hardening fixing
bath.
Sodium thiosulfate, desiccated, can also be used with an
adjustment in the amount.
A couple of general notes on fixing baths:
Sodium thiosulfate will do fine for iodide-containing
emulsions but the fixing time should be extended somewhat.
Nearly all film emulsions contain some silver iodide and
many modern paper emulsions do also. Iodide is both more
difficult to fix and iodide accumulated in the fixing bath
tends to retard fixing. The usual rule is to fix for twice
the time it takes the emulsion to visually clear. This rule
works for reasonably fresh fixing baths. However, an
exhausted bath will not completely convert silver halide to
soluble silver no matter how long fixing is extended. At one
time Kodak recommended extending fixing time to three times
clearing time for tabular grain films, which have a lot of
iodide and are difficult to fix. The solution is to use a
two-bath fixer. Ammonium fixing baths have greater capacity
before they stop fixing effectively and some experts state
that a two-bath fixer is not necessary if a "rapid" fixer is
used, but I think its wisdom as well as an economy to use a
two bath system. In addition, the use of a sulfite wash aid
(I think Ilford still sells this but you can make your own)
will cause some otherwise insoluble silver complexes to wash
out. It effectively extends the capacity of the fixing bath.
Wash aid will also remove residual sensitizing dye from
films where it is persistent such as T-Max. Kodak used to
state that the stain was the result of the dye binding to
the silver due to insufficient fixing but I've encountered
this staining even with very extended fixing in fresh fixer.
The wash aid removes it in a few seconds.
Non-acid fixing.
Unlike developers, which must operate at a certain pH to
work, fixing baths are pretty much independent of pH. What
the acid in a fixing bath is for is two-fold; first, it
stops the developer, and secondly it is necessary for the
non-organic hardeners usually used in fixing baths. If the
hardener is not necessary it can be left out and the acid
can be left out also. While I think it is probably a good
idea to have a certain amount of buffered acid in the fixing
bath to eliminate development while fixing it is not
necessary. However, a thorough rinse in place of the usually
acid stop bath is a good idea. Most of the sodium sulfite
in fixing baths is there to prevent the acid from
decomposing the thiosulfate. If the bath is made neutral
most of the sulfite can be left out, but not all. For one
thing it prevents staining from carried over developer which
may remain active in the fixing bath, and also it prevents
decomposition of the thiosulfate from other sources such as
exposure to the air. Typical fixing baths have about 15
grams per liter of sodium sulfite, if made neutral about 5
grams will do although there is no harm in using more and it
might result in cleaner negatives by preventing any
staining.
I can see no advantage whatever to making a fixing bath
alkaline. The advantages of a non-acid bath are obtained if
its neutral and it will have less tendency to re-activate
carried over developer. If a buffered sulfite wash aid is
used following fixing there are really no advantages to a
non-acid or non-hardening fixing bath other than the lack of
odor.
Also, Ilford makes rapid fixer and the fixing baths for
color processing are rapid fixer. I don't know about current
prices and availability but you may be able to find made-up
rapid fixer at an attractive price.
--
Richard Knoppow
Los Angeles
WB6KBL
dick...@ix.netcom.com