Shelf life for Hypo Clearing Agent?
 

Greetings, B&W Dinosaurs;

Last night, developing some Ilford HP5 rolls, I mixed some new working
solution of Hypo Clearing Agent. The stock solution--stored in a cool, dark
darkroom--had been mixed about a year ago, and smelled VERY strongly of
ammonia. How come? Any ideas on the recommended shelf life of this stuff?

Yes, I mixed a fresh batch, but can anyone explain the strong odor? What
are the decomposition products of clearing agent? Rich Knoppow?

BTW, it is GREAT to see so many diehards still fussing with black and white.
SILVER HALIDES FOREVER!!

Dick Behan
Lopez Island, WA

Shelf life for Hypo Clearing Agent?
 

"R.W. Behan" wrote in message
om...
Greetings, B&W Dinosaurs;

Last night, developing some Ilford HP5 rolls, I mixed some
new working solution of Hypo Clearing Agent. The stock
solution--stored in a cool, dark darkroom--had been mixed
about a year ago, and smelled VERY strongly of ammonia.
How come? Any ideas on the recommended shelf life of this
stuff?

Yes, I mixed a fresh batch, but can anyone explain the
strong odor? What are the decomposition products of
clearing agent? Rich Knoppow?

BTW, it is GREAT to see so many diehards still fussing
with black and white. SILVER HALIDES FOREVER!!

Dick Behan
Lopez Island, WA
Kodak give the shelf life in a filled, sealed, bottle
as three months. Its not long lived because the sulfite,
which is the key ingredient, oxidizes to sulfate with
exposure to the air. Sulfate does not harm but is far less
effective as a wash aid than sulfite.
I am puzzled by the ammonia odor. My guess is that this
is not Kodak Hypo Clearing Agent but something else. There
is no ammonia in the Kodak or Ilford products but there may
be other products based on the old Kodak Hypo Eliminator.
This is a mixture of hydrogen peroxide and ammonia. It
should be avoided for various reasons because the sulfite
wash aids work better. If this is what you have it may have
a very short shelf life. Kodak gives the life of their
mix-it-yourself formula in hours.
I recommend the Kodak product because it has the right
ratio of sulfite to bisulfite and has two sequestering
agents to deal with residue from hardener, where its used,
and with minerals in the water. Ilford's wash aid is a
sulfite wash aid but I have only the information in the MSDS
and can't be sure its buffered. According to the Kodak
research paper and patents the buffering is important.
Another thought, is is possible this was rapid fixer
and not wash aid? That would certainly account for the
ammonia odor. If you mixed Kodak Rapid Selenium Toner in the
wash aid it could also account for the odor. The toner is
mostly ammonium thiosulfate but there wouldn't be much in
the wash aid.


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

Shelf life for Hypo Clearing Agent?
 

For Richard K.....

Awhile back, I was trying to locate my old, original source for the
HCA that I've been using..... The label on my bottles had the formula
and I had come to just remix batches from that and had lost the
source. I'm suspicious that it was from something that you had once
posted long ago. I'm usually careful about keeping sources attached
to my formulas and hadn't done so on this. This is what I've been
using.

Sodium Sulfite 200g/L
Sodium Bisulfite 40g/L
Sodium Citrate 10g/L
EDTA TSSalt 10g/L

Dilute 1:9 for use.

Did this come from you? Do you recognize it and its source? Just
tying up loose ends here but I recall in testing that it was effective
and has become my normal HCA for print duties. I've settled upon TF-4
fixer and no required HCA for film use but didn't want to rethink my
sequencing and related issues for toning/fixing, etc for printing and
continue to use this HCA. If not yours, do you have any opinions,
especially in the Citrate and EDTA usefulness?

Craig Schroeder
craig nospam craigschroeder com

Shelf life for Hypo Clearing Agent?
 

"Craig Schroeder" wrote in
message ...
For Richard K.....

Awhile back, I was trying to locate my old, original
source for the
HCA that I've been using..... The label on my bottles had
the formula
and I had come to just remix batches from that and had
lost the
source. I'm suspicious that it was from something that
you had once
posted long ago. I'm usually careful about keeping
sources attached
to my formulas and hadn't done so on this. This is what
I've been
using.

Sodium Sulfite 200g/L
Sodium Bisulfite 40g/L
Sodium Citrate 10g/L
EDTA TSSalt 10g/L

Dilute 1:9 for use.

Did this come from you? Do you recognize it and its
source? Just
tying up loose ends here but I recall in testing that it
was effective
and has become my normal HCA for print duties. I've
settled upon TF-4
fixer and no required HCA for film use but didn't want to
rethink my
sequencing and related issues for toning/fixing, etc for
printing and
continue to use this HCA. If not yours, do you have any
opinions,
especially in the Citrate and EDTA usefulness?

Craig Schroeder
craig nospam craigschroeder com

It didn't come from me. Its double the strength of the
packaged stuff but the ratios are about right. The formula
in the patent dosen't have the sodium citrate in it although
it mentioned in the list of suitable sequestering agents. No
formula is given in the research paper. I have to do some
digging to get you the citations.


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

Shelf life for Hypo Clearing Agent?
 

Richard--

Thanks a million. I'm not sure the odor was ammonia, but it was strong and
acrid, perhaps more like fresh "hypo."

In any case, it was Kodak Hypo Clearing Agent, and your explanation of what
took place is more than adequate for my curiosity.

Thanks again. You, sir, are a marvel of photographic knowledge.

Cheers,

Dick B.


"R.W. Behan" wrote in message
om...
Greetings, B&W Dinosaurs;

Last night, developing some Ilford HP5 rolls, I mixed some new working
solution of Hypo Clearing Agent. The stock solution--stored in a cool,
dark darkroom--had been mixed about a year ago, and smelled VERY strongly
of ammonia. How come? Any ideas on the recommended shelf life of this
stuff?

Yes, I mixed a fresh batch, but can anyone explain the strong odor? What
are the decomposition products of clearing agent? Rich Knoppow?

BTW, it is GREAT to see so many diehards still fussing with black and
white. SILVER HALIDES FOREVER!!

Dick Behan
Lopez Island, WA

Shelf life for Hypo Clearing Agent?
 

Sodium Sulfite 200g/L
Sodium Bisulfite 40g/L
Sodium Citrate 10g/L
EDTA TSSalt 10g/L

Dilute 1:9 for use.

This looks familiar ... I mix mine up double-strength also.

I got my formula from Richard and doubled the concentrations so as to use a
1:9 dilution rather than a 1:5 to get to working strength. I find 1 gallon
jugs a PITA to pour small amounts from.

I make the S. Citrate from Citric Acid and S. Bicarbonate.

In measuring spoons:

0.5 tsp Citric Acid
1.0 tsp S. Bicarbonate
Small amount of water, let fizz

2.0 l Water
1.0 tsp EDTA (will fizz a bit more)
6.0 tbl S. Sulfite
2.0 tbl S. Metabisulfite

Serve 1:9 with a garni of freshly fixed prints.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/da-main.htm
n o lindan at ix dot netcom dot com