I really don't know, but is it possible that a plasticiser in the saran wrap
is affecting, or being affected by, the presence of thiosulfate in Hypo 2?
If the same thing does not happen to Hypo1, that could perhaps be explained
by the higher silver concentration in Hypo1. I fooled around in Google and
the word "desulfovirga" came up.
Don Sweet
----- Original Message -----
From: "Bogdan Karasek" <bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, December 04, 2009 4:33 PM
Subject: [pure-silver] Re: Problem with 2 tray hypo (fixer).
Hi all,
Just to add to the context and recap.
Nothing has changed in my procedure, same for two years, and this never
happened before, when Hypo1 started to show a slight cloudiness when a
few drops of Hypochek was dropped in, I would dump it and replace it
with Hypo2 which becomes Hypo1 and mix a new batch Sodium Thiosulfate to
make Hypo2. By the book. The last few btaches, nothing changed, the
chemicals came from the same shipment and the same source of distilled
water, same procedure except that last week, Hypo2 turned to an amber
colour after spending the night under Saran wrap. The day before, about
20 prints had gone through Hypo1 and Hypo2. Overnight, Hypo2 turns
amber yet Hypo1 is still clear despite being a Hypo2 in a previous
cycle. I dump the amber Hypo2 and mix a fresh batch of Hypo2, Hypo1
stays the same, put about 10 prints through both, cover both Saran Wrap
for the night and the next morning, Hypo2 is amber coloured.
Never happened before and now, twice in a row with an unchanged
procedure that I have been doing for several years. Twice with the
Hypo2 but never with the Hypo1????
I am flumuxed, to say the least. Other than the dektol, Stop, and a
holding tray filled with water next to Hypo2, I don't see any other
source of contamination.
If I have some time tomorrow, I'll do the tests that Richard proposed to
see if Hypo2 is still good. But still, only 10 8x10's went though
Hypo2, so why wouldn't it still be good???
Just a question... if it is sulphurized Hypo, where would the sulphur
have come from? There is none in the darkroom.
And I'll mix my next batch with sodium sulfide.
And I will report back with the results.
Thanks all,
Bogdan
In Montreal,
Scratching his head
Richard Knoppow wrote:
----- Original Message ----- From: "Bogdan Karasek"
<bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, December 03, 2009 3:02 PM
Subject: [pure-silver] Problem with 2 tray hypo (fixer).
Hello,
I need some advice/clarification regarding my fixer. When
printing fiber paper, I use the two tray method for my
fixer and I mix it myself using Sodium Thiosulfate in
distilled water. When tray I is exhausted, I do the usual
routine, move the hypo in tray II to tray I and mix a
fresh gallon of hypo for tray II.
Recently, a phenomenon has happened for which I have no
explanation. If I am doing intensive work over several
days, I leave the the chemicals, Stop and Hypo (developer
gets changed everyday) in their trays overnight but each
tray is covered with Saran Wrap to prevent oxidation.
Never had a problem until last week. Overnight, Hypo II
changed colour to a light amber (see photo) whereas hypo I
did not. I checked hypo II for exhaustion using Edwal's
Hypochek and everything was clear. As a precautionary
measure, I mixed fresh hypo for tray II, covered it with
Saran Wrap at the end on the evening and next morning,
tray II has the amber colour whereas tray I is clear. I
checked tray II with the Hypochek and again, no evidence
of exhaustion.
Since an image is worth a 1000 words, what you see in the
photo are the contents of tray I on the left, clear, and
tray II on the right, amber coloured.
By the way, the developer is Dektol 1:2 and the stop is
Kodak Indicator Stop Bath. Nothing has changed in my
procedure, same trays for the past number of years, always
mix chemicals with distilled water.
Anybody have an explanation? This has never happened to
me before.
http://s873.photobucket.com/albums/ab296/bkarasek/?action=view¤t=Hypo12-01.jpg
Cheers,
bogdan
I don't have an explanation but if you are using plain
hypo you should be adding some sodium sulfite to it to
preserve the thiosulfate. Where there is no acid about 5
grams per liter is enough although more won't hurt. Plan
hypo oxidizes pretty fast without the preservative.
If this happened only once I suspect something got
spilled into the tray.
Hypo-Check shows dissolved silver as a precipitate but
will not show other problems such as sulphurized hypo. I
have some question about its reliability since the dilution
is unknown so the threshold of showing the precipitate is
also unknown. Hypo can be checked indirectly by using a
residual silver test on a scrap of paper or film fixed in
it. The simplest test is a 1:9 dilution of Kodak Rapid
Selenium Toner. However, this fails if there is much hypo in
the material so it should be well washed before testing. The
standard test is a solution of sodium sulfide but the
Selenium toner works as well providing the material is
washed and the test solution does not smell and lasts longer
than the sulfide solution. The test is made in exactly the same way as
the sulfide test, place a drop of solution on the emulsion in a clear
area and allow it to sit for about two minutes. Then rinse off and look
for any staining. Properly fixed film or paper should show no stain. If
there is silver halide present there will be a yellow or
brown stain. The Kodak Hypo Estimator comparitor works for
the Selenium test as well as the sulfide test but there
really should be no stain at all.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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