Auteur: zonesys
Date: 30-11-2006 17:42
Je me suis un peu planté...Après une nouvelle recherche sur internet, j'ai trouvé une formule de fixateur alcalin avec du thiosulfate d'ammonium :
Ammonium thiosulfate 57-60% 800 ml
Sodium sulfite anhydrous 60 g
sodium metaborate 5g
water to make 1L
Working solution: dilute 1:4 with water
Ci-dessous un court texte en anglais qui résume bien les avantages d'un fixateur alcalin :
Although it is more convenient to use acid fixers simply because they are
readily available, film processing should ideally take place in high salt
solutions at or near the pH of the developer.
"There are several advantages to using an alkaline fixer:
1. Alkaline fixers do not dissolve image-bearing silver. Theefore, there is
less danger of over fixing.
2. Alkaline fixers allow shorter washing times. Removal of hypo is faster
than when an ordinary fixer plus a hypo clearing agent is used. Film fixed
in an alkaline fixer does not require hypo clearing agent: hypo is down to
archival levels afer a minute of washing. But film shout be washed a total
of at least three minutes to ensure all developer residue is removed.
3. Keeping the entire system either neutral or alkaline, from alkaline
developer, netural water stop, alkaline fixer, neutral final wash (w/o HCA),
will improve the permanence of all films and papers because the thiosulfate
does not mordant to the silver image or base.
4. Alkaline fixers have greater capacity than acid fixers.
5. Alkaline fixers are easier to formulate and more stable as thiosulfates
are more stable in an alkaline solution.
6. Alkaline fixers can be formulated to have very low odor."
|
|
