I’ve been using the following sequence of baths recently, Developer, water,
stop, fix1, fix2, wash. I’m not advocating this, its just what I do. My
observation is simply this, when dumping the post developer water bath, there
is a very significant amount of carry over from the developer in there.
This is for prints, not film.
In the past, I’ve run into silver plating on negatives, using Tmax developer,
and tap water. If detected early, I’ve been able to just rub it off with my
fingers. I’ve also encountered it when printing onto an obscure material, Kodak
Polycontrast print film. This is, or at least was, a known problem.
I have also noted a slight silvering on prints, on the very rare occasions,
when I get fix on my fingers, and then touch the paper with damp fingers before
development. I’m sure I am the only photographer on this list who has noted
this, because I am sure all of the rest of you have scrupulously correct
darkroom practices.
Best regards
Laurence Cuffe
On 19 Mar 2021, at 15:07, BOB KISS <bobkiss@xxxxxxxxxxxxx
<mailto:bobkiss@xxxxxxxxxxxxx>> wrote:
DEAR RICHARD,
Good info! Additionally:
1) One reason ammonium thiosulfate fixers are considered more archival is
that ammonium ions are complexing agents as well as the thiosulfate ions so
they add to the fixing process by making unexposed, undeveloped silver halide
crystals soluble. Further, they keep the thiosulfates from forming the
dreaded, large, nearly insoluble, silver-thiosulfate complexes common to
exhausted fixers that are the most difficult to wash out. So the ammonium
performs double duty in making the fixer "more archival" because it promotes
the washing out fixing byproducts of both film and paper more quickly.
2) You made the point that ammonium thiosulfate fixers can bleach image
silver when in an acid state...true! An EXCELLENT reason NOT to use stop
bath when using an ammonium thiosulfate fixer...yes?
3) Another person mentioned that he could rinse film for 30 sec between dev
and ammonium thiosulfate fixer but was concerned about the possibility that
fiber base paper would carry over dev into the fixer and keep developing.
This is why a 2 minute WASH, (not rinse) in running water is recommended for
fiber base prints between dev and ammonium thiosulfate fixers. But, see #2
for a very good reason NOT to use an acid stop bath unless you THEN do a two
minute wash to remove the acid before going into the ammonium thiosulfate
fixer. IMHO it is easier to just wash the print 2 mins between dev and fix.
CHEERS!
BOB
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>
[mailto:pure-silver-bounce@xxxxxxxxxxxxx ;
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>] On Behalf Of `Richard Knoppow
Sent: Friday, March 19, 2021 10:44 AM
To: pure-silver@xxxxxxxxxxxxx <mailto:pure-silver@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: simple stop bath recipe?
Neither sodium or ammonium thiosulfate requires an acid pH
to work. The statement "they are more archival" requires some
justification. The purpose of the fixing bath is to convert
whatever silver halide is left undeveloped to a water soluble
form. Residual halide can decompose with time causing staining or
fading.
Ammonium thiosulfate has a greater rate of fixation and is
also more effective for silver iodide. High speed emulsion (most
film emulsions and some paper emulsions) have enough silver
iodide to require extending their fixing times. Ammonium based
fixer is more effective for these but reasonably fresh sodium
fixer is just as effective provided fixing time is sufficient.
Ammonium fixer can cause bleaching due to dissolving some
metallic silver, when in acid condition. So, an ammonium fixing
bath should not be as acidified as is common practice for sodium
fixers. However, when containing an alum hardening agent the pH
is determined by the requirements of the hardener so is the same
for either kind.
Most modern emulsions do not need the hardening provided in
many fixing baths. If the hardener is left out a much higher
(more alkaline) pH is sufficient to prevent activation of carried
over developer. It IS necessary for fixing baths of any type to
contain enough sodium sulfite, or its equivalent, to both prevent
staining from reaction products of any carried over developer and
also prevent decomposition of the thiosulfate buy any acid in the
developer and by atmospheric oxidation. An effective fixer need
contain only either sodium or ammonium thiosulfate and a minimum
amount (about 5grams/ liter) of sulfite.
Some later fixer formulas were devised to reduce odor. These
generally have less acid in them. Also, Kodak found that a
buffering the acid with borax would result in less effect from
carried over alkaline developer (see F-5).
A note: Dichroic fog has many causes. They are well covered
in the literature. It is defined as a thin deposit of metallic
silver in the very find state of division called "colloidal" on
the surface of the emulsion. It is thin enough so that it appears
blue by reflected light and yellow by transmitted light, hence
the name. In some cases it can be wiped off the surface while the
emulsion is still wet but not after it dries.
The silver deposit found on old film and prints is not the
same thing. This stain, sometimes called "mirroring" is caused by
oxidation of image silver and consequent migration of the oxide
and sometimes reconversion to metallic silver. It can take place
in perfectly fixed and washed emulsions. In fact, it is what is
prevented by slight sulfiding of the image silver. Silver is
normally difficult to oxidize. The blackening of silver objects
is almost always silver sulfide and the silver of photographic
images is also subject to sulfiding from chemicals in the air.
However, the special circumstances of silver in a photographic
emulsion make it vulnerable to oxidation. Silver sulfide is
extremely stable and is not subject to either oxidation or
further sulfiding. This is the purpose of the slight toning by
using a polysulfide toner. Complete toning with other toners is
also very effective but changes the appearance and structure of
the image so the polysulfide toner is preferred where protection
with minimum other changes are desired.
It was found that very complete washing would make the image
less stable because it made the image silver more vulnerable to
oxidation and sulfiding. A slight residue of thiosulfate causes a
very slight sulfiding which tends to protect the metallic silver.
The problem is that when this is provided by simply limiting
washing it is not predictable or controllable where toning is.
I didn't mean to write this much and am not sure I really
addressed the issue.
On 3/19/2021 6:58 AM, BOB KISS wrote:
The entire issue of stop or wash can be made moot simply by
using an ammonium thiosulfate neutral or slightly alkaline
fixer.They are more archival and you only need a wash between
dev and fix.
*From:*pure-silver-bounce@xxxxxxxxxxxxx
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>
[mailto:pure-silver-bounce@xxxxxxxxxxxxx ;
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>] *On Behalf Of *John
Stockdale
*Sent:* Thursday, March 18, 2021 8:52 PM
*To:* pure-silver@xxxxxxxxxxxxx <mailto:pure-silver@xxxxxxxxxxxxx>
*Subject:* [pure-silver] Re: simple stop bath recipe?
Ryuji Suzuki wrote on the subject some years ago. I think he
suggested a buffered stop to avoid masssive swings of pH from
alkaline developer to quite acidic stop. Over at photrio.org
<http://photrio.org/>
there is a current thread with 1000 posts! FWIW I use water
for film and then a fixer that's only mildly acidic (C-41
type). For paper I always use as a stop sodium metabisulphite
brought up to pH=5.5 or 6 with some hydroxide, following
Suzuki's suggestion. I found that using water as a stop for
paper took too long and wasted water, and I had staining that
appeared later if it was too short or insufficiently fresh.
=================================================================
On 19/03/2021 9:18 am, BOB KISS wrote:
URGENT: You really should use a stop bath with film if you
are using an acid fixer.I started doing photo
conservation/archiving work nearly 30 years ago and
enlisted the aid of Jose Orraca, a world famous photo
conservator, a number of photo historians, and the
remaining synapses from my under grad and grad photo chem
from RIT.Something that kept showing up in older negatives
was dichroic fog.When asked, ALL my advisors said it
resulted from the film going from alkaline developers into
acid hardening fixers without stop bath.
NOW: if you use a neutral or slightly alkaline fixer like
TF-5 or most other ammonium thiosulfate fixers, no prob.But
alkaline dev to acid fixer, you have probably cursed your
negs to dichroic for in the future.Before digitization and
numerous redundant data storage systems, the negative was
revered as "the" document and the print as the artist's
statement...Adams said, the negative is the score, the
print the performance.
I am sure that Richard will look into his extensive
documentation and confirm what I claim above...
*From:*pure-silver-bounce@xxxxxxxxxxxxx
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>
<mailto:pure-silver-bounce@xxxxxxxxxxxxx ;
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>>
[mailto:pure-silver-bounce@xxxxxxxxxxxxx ;
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>
<mailto:pure-silver-bounce@xxxxxxxxxxxxx ;
<mailto:pure-silver-bounce@xxxxxxxxxxxxx>>] *On Behalf Of
*MARK SAMPSON (Redacted sender "msampson45" for DMARC)
*Sent:* Thursday, March 18, 2021 5:57 PM
*To:* pure-silver@xxxxxxxxxxxxx <mailto:pure-silver@xxxxxxxxxxxxx>
<mailto:pure-silver@xxxxxxxxxxxxx ;<mailto:pure-silver@xxxxxxxxxxxxx>>
*Subject:* [pure-silver] Re: simple stop bath recipe?
Interesting. TF-5 is alkaline and non-hardening... the lack
of which has not caused any problems with the prints. I’ve
been told that TF-5 is buffered and doesn’t require a stop
bath, a water rinse is good enough. I guess I’m being
traditional by using a stop bath.
I time the stop bath for the usual 30” and have not noticed
any continued development in the fixer. Never imagined such
a thing could be possible- even after 40+ years in the
craft. Live and learn!
Mark S
Sent from my iPhone
On Mar 18, 2021, at 2:17 PM, Wilbert van den Berg
<wilbert@xxxxxxxxxxxxxxx <mailto:wilbert@xxxxxxxxxxxxxxx>>
<mailto:wilbert@xxxxxxxxxxxxxxx ;<mailto:wilbert@xxxxxxxxxxxxxxx>>
wrote:
15 gr of citric acid in 1 liter of water.
Le 18/03/2021 à 21:58, `Richard Knoppow a écrit :
Citric acid works fine where the fixer does not
have alum hardener. It has the virtue of not having
a vinegar odor. Can also be used in non-hardening
fixing baths. Actually, fixers do not need to be
acid, the fixing action is independent of pH but
they are made acid partly because the alum hardener
needs it and also to make sure any developer
carried over is inactivated. A stop bath will
usually take care of the developer but the usual
few second stop bath does not wash out the
developer which can become active again if put into
an alkaline bath.
--
wilbert@xxxxxxxxxxxxxxx <mailto:wilbert@xxxxxxxxxxxxxxx>
<mailto:wilbert@xxxxxxxxxxxxxxx ;<mailto:wilbert@xxxxxxxxxxxxxxx>>
04 73 72 19 20
"Quand on se retrouve du côté de la majorité, il est temps de
prendre du recul et de réfléchir."
Mark Twain
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>>
Virus-free. www.avg.com <http://www.avg.com/>
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>>
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org
<//www.freelists.org/> and
logon to your account (the same e-mail address and password you
set-up when you subscribed,) and unsubscribe from there.
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>
WB6KBL
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org
<//www.freelists.org/> and logon to your account (the same e-mail
address and password you set-up when you subscribed,) and unsubscribe from
there.
