Advice on monochrome process

"Mark" wrote in message
...
Richard,

The advantage of a neutral or alkaline fixing bath in
washing is considerable when no wash aid is used. There
are
two reasons acid hardening fixing baths are hard to wash
out.

Ok, I certainly plan on using a washing aid and unless I
start
experiencing emulsion damage I don't want a hardening
fixer for film
or prints.

If an alkaline
bath is used after an acid fixer the emulsion will wash
out
as fast as if an alkaline fixer had been used.

This is good to know. But what about the actual paper
fiber? Rapid
fixing is supposed to have an advantage there.

So, while non acid processing set ups work fine I
continue to use the old fashioned type along with KHCA.

The fixer type choice seems to have as much to do with
processing
style and how much/how often you process as it does with
effects on
washing and toning. Storage and re-use are a factor. I
like the idea
of inexpensive plain fixer used one-shot (and no need for
a second
bath), or mixing amounts for one printing session. But
for T-grained
films, if you're doing a lot of processing fairly often,
it may make
more sense to use a rapid fix to save processing time and
get lots of
work out of a quantity of solution.

At any rate your various postings have been educational!

The washing out of the fiber support is more difficult
than washing of the emulsion itself. The problem is that the
paper fibers tend to bind the thiosulfate which must be
removed by frictional forces during washing. The use of a
Sulfite wash aid helps because of the ion exchange property
but it is much less effective for the paper base than for
the emulsion or baryta sizing layer. Note the difference in
wash times for RC paper or film and fiber base paper. RC
washes out sufficiently in 4 minutes even when acid
hardening fixer is used without any wash aid. Film takes
much longer because it has a thicker emulsion than paper but
the wash time is still only about half an hour. Fiber paper
takes much long depending on the thickness of the base, 1
hour for single weight paper and 2 hours for double weight
paper. If a non-hardening and non acid fixing bath is used
these times are cut about in half. When a sulfite wash aid
is used they are cut to about 20% of the original time.
Ilford has a system of fixing and washing that is
supposed to result in much faster wash times for fiber paper
by using a fixing time so short that the hypo can not soak
into the fibers of the support. Ilford measured the amount
of hypo taken up by the base and found that if fixing could
be done within 30 seconds very short wash times were
sufficient providing non-hardening fixer and a sulfite wash
aid was used. Unfortunately, very few papers will fix out in
this time even with film strength rapid fixer. The limit of
time for the process to offer any advantage over normal
fixing procedures is about one minute. Many papers _will_
fix out in this time, but others need up to 2 minutes in
rapid fixer. The advantage of the Ilford system diminishes
rapidly with fixing times over 1 minute.
If one compares the total time for fixing, treating in a
wash aid, and washing, it turns out there is little
advantage in the Ilford system although I have not seen
comparitive figures for the amount of hypo left in the paper
fibers.
Ilford recommends a treatment of 10 minutes in a sulfite
wash aid. Kodak recommends 3 minutes for double weight
paper. Kodak published a technical paper on the wash aid. In
it is a graph showing effectiveness vs time. The curve is
asymtotic reaching about its maximim effectiveness at around
3 to 4 minutes. However, this is for the emulsion, not the
support, so longer times may be benificial. Ilford does not
make clear in its published report what the effect of
varying the treatment time in wash aid was.
So, there is an advantage for rapid fixer for fiber paper
mainly if the paper will fix out rapidly enough to prevent
much absorption of fixer by the base.
Note that _acid_ rapid fixer will dissolve metallic
silver slowly. This can bleach the highlights of paper,
especially warm tone paper, if left in the fixer too long.
Neutral or alkaline rapid fixer does not bleach.
Note that the emulsions of fiber and RC paper are very
similar. Long fixing times for fiber paper are partly a
hold-over from old recomendations based on poor darkroom
practice and assuming partially exhausted fixer. I am told
by Dave Valvo, retired from Kodak, that another reason is
that there can be some halide in the baryta layer which is
hard to fix out. I have not tried to varify this by using a
residual silver test. Unless this effect is significant
fiber should fix out in about the same time as RC. Another
reason for the recommendation of very long fixing times in
old literature is to give adequat time for the hardener to
work. Since the hardener is of little importance in modern
practice, often not even used, the fixing time should be
based entirely on how long it takes to convert the halide
into soluble form.
One-shot fixing.
This is misleadingly attractive. One poster here
recommends using highly diluted fixer one time. This is
likely to result in incomplete fixing for the same reason
that applies to exhausted fixer, namely, not enough
thiosulfate ions being available to complex the halide. At
least 3 thiosulfate ions are needed to complex one silver
ion. If not enough thiosulfate ions are available some of
the halide remains in a partially converted form that is
either not soluble or is very tightly bound to the emulsion.
Wash aid can free some of this last but does nothing for the
insoluble halides. Two bath fixing is both effective and
economical. It may not be necessary when rapid fixer is used
because rapid fixer can tollerate a larger amount of
dissolved silver and still complete the fixing reactions.
Nonetheless, since residual halides in the emulsion are very
destructive to the image silver with time IMO a two bath
system should be used with either kind fo fixing bath.

This is is a long answer to a short question but I find that
incomplete information can be misleading and try to avoid
it.


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

Mark wrote:

lots of methods and things may have changed since
the 30 year old old Ansel Adams and Fred Picker
books were published! Mark


One notion needing more of a change is the notion
that fixer need be quite strong if it's to have lots of capacity
and work fast. Lots of capacity means lots of dissolved silver
in the fixer. No one wants that. After all there are archival
limits for film as well as paper.
Last night I processed a 120 roll of HP5+. It was fixed
in 1/2 liter of solution containing 1/64 liter or 15.625 ml of
unadulterated A. Thio. concentrate; 1:32, ph 7.5.
I checked after 6 minutes. The roll was clear and had no
sign of color. I allowed 3 more minutes. I'll repeat the
test and check after 3 minutes.
An archival fix using fresh fix and well within ten minutes.
I think it worth the 2 or 3 minutes more. Dan

On Mon, 13 Feb 2006 00:11:08 +1100, "otzi" wrote:

On the question of hypo leeching into the fibres of the support, in the
worst case scenario, How far into the papers edge would this be? 1/4" +/-
--
Otzi

Complete saturation to the baryta layer. In the past it was common to
leave prints in fixer for hours. It really just depends on the papers
qualities and how long it will take to wash the fix out. If needed,
one can always use a hypo-eliminator and then reintroduce a minimal
amount of hypo with the toner to help with archival stability.

==
John - Photographer & Webmaster
www.puresilver.org - www.xs750.net

wrote:

Mark wrote:

lots of methods and things may have changed since
the 30 year old old Ansel Adams and Fred Picker
books were published! Mark


One notion needing more of a change is the notion
that fixer need be quite strong if it's to have lots of capacity
and work fast. Lots of capacity means lots of dissolved silver
in the fixer. No one wants that. After all there are archival
limits for film as well as paper.
Last night I processed a 120 roll of HP5+. It was fixed
in 1/2 liter of solution containing 1/64 liter or 15.625 ml of
unadulterated A. Thio. concentrate; 1:32, ph 7.5.
I checked after 6 minutes. The roll was clear and had no
sign of color. I allowed 3 more minutes. I'll repeat the
test and check after 3 minutes.
An archival fix using fresh fix and well within ten minutes.
I think it worth the 2 or 3 minutes more. Dan


A correction and a couple of observations:
That A. Thio. dilution should read 1:31. I would expect any
A. Thio. based off the self concentrate will work at the same
dilution. That same number of ml of A. Thio. concentrate
may be substituted by the same number of grams of
S. Thio. anhydrous.
An acid stop stops instantly. A few find that important.
For some an immidiate and total shut down of the developing
process is essential. For others stopping is a secondary
matter and a consequence of washing out all but the
very last trace of developer. The acid stoppers are
interested in stoping and the water stoppers are
interested in washing.
The Ilford Archival Processing Sequence. It is no more.
They do still recommend the 5-10-5 minute - wash, Ilford HCA,
wash - routine. They do not however differentiate twixt the 1:4 or
1:9 dilutions; fix 1 or 2 or 3 minutes. That includes their S. Thio.
based fixer. They do very much suggest the two bath method
and they do make a point of mentioning the low silver
per unit volume needed for extended keeping. IIRC
the word Archival is not mentioned once.
How about that? Dan

In article ,
John wrote:

On Mon, 13 Feb 2006 00:11:08 +1100, "otzi" wrote:

On the question of hypo leeching into the fibres of the support, in the
worst case scenario, How far into the papers edge would this be? 1/4" +/-
--
Otzi

Complete saturation to the baryta layer. In the past it was common to
leave prints in fixer for hours. It really just depends on the papers
qualities and how long it will take to wash the fix out. If needed,
one can always use a hypo-eliminator and then reintroduce a minimal
amount of hypo with the toner to help with archival stability.

==
John - Photographer & Webmaster
www.puresilver.org - www.xs750.net

Was it William Henry Jackson that made the huge
plates through the west? I went to a photo exhibit
a few years back Photographers of the west That had AA and others I
think it was one Jackson's prints that showed very serious image
deterioration, in what appeared to me as bad fixation and mold growing.
Shame as most of the original plates were scraped to produce more
imagery as they proceeded along the journey.



--
"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

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