how many 8x10 papers can a liter of F-6A fixer process?

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Steven Woody - 31 Aug 2006 12:45 GMT

thank you.

-
woody

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darkroommike - 01 Sep 2006 16:44 GMT

> thank you.
>
> -
> woody

Nice straight answer? It depends.

Here are the variables to consider:
Type of paper, FB or RC
One bath fixing or two.
And the water you use to mix the fixer.

The best way to find your answer is to test yourself in your own
darkroom, Vestal in his book, The Art of Black and White Enlarging, has
a good test sequence.

If just starting out and no time to test, here's what I would do for an
FB sequence. And since I am not using f6A this is literally what I would
do until I had time to test:

Use the two bath method. Mix two four liter batches of F-6a. Calculate
Kodak's recommended usage for four liters of F-6 (if I can't find one
for F6-a (always a problem when using modified formulas)) and then
DIVIDE BY TWO. Let's say that the number of prints per 4 liter bath
equals 100.

Discard fix bath one after one hundred prints, pour bath two into the
bottle labeled fixer one and mix another four liters of fixer two.
Discard both fixers every thirty days. This is very conservative
practice and will go a long ways to ensuring your prints will be around
in good shape a long time.

Note it's fun to experiment with formulas but if your not doing 100
prints a month you'd probably be better off buying prepackaged fixers
and not mixing your own.

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darkroommike

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Richard Knoppow - 01 Sep 2006 19:32 GMT

> thank you.
>
> -
> woody

Kodak F-6a is a stock hardener solution for fixer formula
F-6. If you have F-6a, it is not a complete fixer. F-6 is
given as an oderless fixer.
Since the amount of thiousulfate in F-6 is the same as in
F-5, which is what packaged Kodak fixer is, the capacity is
about the same. The capicity depends on how well fixed the
prints are to be. For archival purposes the capacity of a
single fixing bath is very limited, Ilford states its no
more that about 10 8x10 prints per _gallon_. Kodak gives the
capacity as 100 8x10 sheets per gallon but that is probably
for "commercial" use with a 25 year expected lifetime. By
using two successive baths the archival capacity can be
increased by about 10 times, that is, to the same amount as
for the less permanent commercial standard.
The degree of fixing can be tested with either of two
simple test formulas. One is a 1% solution of Sodium
Sulfide, the other is a 1:9 dilution of Kodak Rapid Selenium
Toner. The toner test solution will fail if there is a lot
of residual hypo in the print (must be well washed before
testing). Place a drop or two on a clear area of the print.
Allow it to stand for about 2 minutes, blot off and examine
for any stain. There should be no detectable stain with
either test. The prints to be tested should be wet not have
surface moisture. Its best to use a small sample of paper
processed along with the prints because any stain from the
test solution can not be removed. If a stain appears the
prints should be refixed in fresh fixer.
Someone else has given instructions for the two bath
system of fixing. You can also find this is several Kodak
publications.

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---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com

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darkroommike - 02 Sep 2006 15:08 GMT

>> thank you.
>>
[quoted text clipped - 31 lines]
> system of fixing. You can also find this is several Kodak
> publications.

What Woody is referencing is the Ansel Adams version of F-6, not the
hardener formula. Maybe to eliminate confusion it should have been
named F-6AA. It's just F-6 with less alum, see:
http://www.jackspcs.com/f6a.htm

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darkroommike

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Steven Woody - 02 Sep 2006 16:57 GMT

> >> thank you.
> >>
[quoted text clipped - 36 lines]
> named F-6AA. It's just F-6 with less alum, see:
> http://www.jackspcs.com/f6a.htm

yes, what i said is the Adams's version of F-6, and it was said as f-6a
in jack's site.

i am processing 8x10 RC papers.

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Lloyd Erlick - 02 Sep 2006 21:43 GMT

>yes, what i said is the Adams's version of F-6, and it was said as f-6a
>in jack's site.
>
>i am processing 8x10 RC papers.

September 2, 2006, from Lloyd Erlick,

Is hardener really necessary for this type of
material??

F6 minus the hardener ... minus the acetic
acid (needed because of hardener) ... leaves
the fixer Adams called 'plain fixer' - in the
appendix to 'The Print'. Fixer can't get
cheaper, easier or quicker to prepare.

But the original poster seems to be trying
various materials and formulas for
educational purposes ... so Kodak fixer F5
would be in order. The formula usually
specifies a gallon, but only a liter or even
half a liter is enough (for educational
purposes, that is ...). The smell of F5 is
powerfully obnoxious (no wonder they called
it darkroom fumes). It's very interesting how
F6 eliminates the smell! If one prepares F6
slightly differently (add acid *after* the
alkali) from the usual presentation of the
formula (acid added to the mix before the
alkali) there is no smell at all.

Both F5 and F6 are of academic interest. Most
current production materials (the films and
papers, RC and FB, found in a 'usual'
darkroom like mine) require no hardener. In
addition, I prefer a low-capacity fixer
because with relatively low throughput in my
darkroom, it takes too long to exhaust a
commercial, so-called, rapid fixer.

I like to make up fixer with distilled water,
so no sequestering or chelating agent is
necessary, either.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
website: www.heylloyd.com
telephone: 416-686-0326
email: portrait@heylloyd.com
________________________________
--

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Richard Knoppow - 03 Sep 2006 22:10 GMT

>>> thank you.
>>>
[quoted text clipped - 38 lines]
> confusion it should have been named F-6AA. It's just F-6
> with less alum, see: http://www.jackspcs.com/f6a.htm

An unfortunate confusion. The amount of hardener does
not matter, it takes no part in the fixing process. In fact,
it can be left out altogether, Kodak F-24 is a non
hardening, low odor formula.
The capacity of a fixing bath depends on the amount of
thiosulfate in it. It takes about three thiosulfate ions to
convert one silver halide molecule. Ions which become bound
to halide are no longer available to convert more. While one
can test the hypo bath for dissolved silver by means of the
simple Potassium Iodide test it is indirect. Testing a print
or test paper using a solution which reacts directly on the
remaining halide is superior.
Several years ago Michael Gudzinowicz, who is a Phd
chemist, wrote a complete description of the fixing process
to this list. Google may be able to find it. The fixing
process is not simple, but rather a chain of reactions each
resulting in the halide complex being more soluble. The
fixer must be prett fresh to complete this chain and allow
the unused silver halide to be completely washed out of the
emulsion. Two bath fixing is helpful because the first bath
does most of the work leaving the second bath relatively
fresh to clean up any remaining incompletely converted
halide.
Most conventional fixer formulas are acid because they
are intended to contain a hardener. It is the hardener which
must work in an acid bath, hypo works equally well in acid,
alkaline, or neutral solutions. However, the odor associated
with hypo is from the acid. The acid would decompose the
thiosulfate very quickly so a relatively large amount of
sulfite is added. Some sulfite decomposes releasing Sulfur
dioxide gas which has a sharp odor and can be very
irritating. By eliminating the hardener the pH can be
whatever one wants. A somewhat acid bath is still desirable
to prevent carried over developer from being active in the
fixing bath but much less acid is needed for this. Neutral
fixing baths have very little odor but an acid stop bath can
not be used so film or paper must have a short and rather
rapid wash between the developer and fixing bath. Alkaline
fixing baths, which are currently popular, have no advantage
over a neutral bath.

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---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com

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Lloyd Erlick - 04 Sep 2006 17:14 GMT

>Kodak F-24 is a non
>hardening,

low odor formula.

September 4, 2006, from Lloyd Erlick,

I beg to differ. In fact, I'd say anyone who
mixes F-24 in a sink and holds their head
over it will smell it quite prominently. It
smells like good ol' acid fixer. The same is
true of the version that specifies citric
acid instead of acetic.

I know many long-term sources claim F-24 is
low odour, but it only needs to be mixed to
prove it is far from it.

Low odour fixers are easiest to make sans
acid, although F-6 is an odorless, acid
fixer. But it's acid because it's a hardening
fixer, and who needs hardener? Without
hardener and acid, F-6 is pretty much Ansel
Adams' 'plain fixer' (water, sulfite and
thiosulfate). Probably a member of the
'neutral' category.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
website: www.heylloyd.com
telephone: 416-686-0326
email: portrait@heylloyd.com
________________________________
--

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