Re: Substitute fixer for silver?

eml@gate.net
Thu, 16 Nov 1995 13:00:59 -0500 (EST)

Sam Wang
>
> This is not related to what we normally regard as alt.photo.process, but I
> need to find an alternative to the regular fixers for processing of black
> and white films and papers. Does anyone have experience with good
> substitutions? "Good" in terms of breathability(sorry, Webster) and
> functionality.
>
> Please e-mail me your comments if this topic is not appropriate to this
> list. Thanks!
>
> Sam
>
>
Thiosulfate fixers outgas far less Sulfur Dioxide if they are
basic or neutral or only weakly acid. So-called odorless fixers
usually rely on Boric Acid as the acidifier, resulting in a
very large reserve of very weak acidity. Formulae can
be found in a lot of texts.

Unfortunately, there are very few silver halide solvents which
are practical fixers. The next most practical after
Sodium or Ammonium Thiosulfate are Sodium, Ammonium, and Potassium
Thiocyanates. All are much more expensiove, and act very quickly
with the risk of bleaching of the silver image being much greater
than with Thiosulfates. An alkaline Thiocyanate/Sodium Sulfite
fixer should be as nearly odorless as you can get. But it might
be better to use an alkaline or neutral Thiosulfate fixer, since
they are slower and more predictable in action. I honestly don't
know what would happen to a chlorbromide paper fixed in Thiocyanate.
Image bleaching if you're not careful is a real possibility.

Kodak had a formula many years ago for an odorless fixer, F6.
The formula is as follows:

Water (125F) 600ml
Sodium Thiosulfate 240 Grams
Sodium Sulfite(Anhyd) 15 Grams
Acetic Acid (28% Sol.) 48ml
Kodalk 15 Grams
Potassium Alum 15 Grams
Cold water to make: 1000ml

The 1946 Photo Lab Index (Morgan & Lester) says:

"This new fixing bath has been prepared for those who are sensitive
to Sulfor Dioxide even in the small concentrations which sometimes
emanate from a newly prepared tray of F-5. [the standard Kodak fixer
of the time] The odor of Sulfur Dioxide is eliminated almost entirely
by omitting from Formula F-5 the Boric Acid and substituting for it
15 Grams of Kodalk per litre."

Hope this helps you out.

Edward M. Lukacs, LRPS
Miami, Florida, USA

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