Helen Bach
(K=2331) - Comment Date 5/17/2006
|
The full answer would be rather long, and not everyone agrees on the story. Here goes for a brief, simplified version:
Neutral or alkaline fixers are easier to wash out of film or paper than acid fixers, so they are preferred by many for that reason. Over-fixing (removing image silver) is much less likely with alkaline fixer. On the other hand, acid fixers have been in common use for decades, and print longevity hasn't been a problem. The use of a hypo clearing agent is recommended if you use acid fix, but unneccessary if you use neutral or alkaline fix. If you use a neutral or alkaline fixer the whole process can be alkaline or neutral, with no swings in pH.
There aren't many neutral or alkaline fixers available commercially. Agfa FX Universal is an ammonium thiosulphate (ie rapid) neutral fixer, but I'm not sure of the availability now. Photographers Formulary TF-4 is an alkaline rapid fix. Alkali-Fix from monochromephotography.com is also an alkaline fix, not surprisingly.
Acid fixer is usually something like ammonium thiosulphate, sodium sulphite, boric acid and acetic acid. In an alkaline fixer the acids are replaced by something like sodium metaborate.
As I said, this is only a small part of the story.
Best,
Helen
|
|
|
|
ann clancy
(K=2014) - Comment Date 5/18/2006
|
Just to add something to Helen' s review.
Either type will work on all paper and both types work. It just depends on the availibity of products in your location and personal preferences.
|
|
|
|
Ahmad Hasan
(K=4164) - Comment Date 5/19/2006
|
thanks alot Helen You 've always been of great help for me ,please do you know any detailed source for information about the exact chemical components of the alkaline fixative .
|
|
|
|
ann clancy
(K=2014) - Comment Date 5/20/2006
|
Check "the Darkroom Cookbook " by Steve Ancell. There are several formulas for alkaline rapid fixers.
|
|
|
|
Ahmad Hasan
(K=4164) - Comment Date 5/20/2006
|
thanks alot Ann its very kind of you ,Iam really grateful
|
|
|
|
Helen Bach
(K=2331) - Comment Date 5/20/2006
|
Jack's Chemistry Site has a useful collection of formulae.
Here's TF-3, a rapid alkaline fixer from Anchell and Troop:
http://www.jackspcs.com/tf3.htm
The formula of their TF-2 standard alkaline fixer is mentioned by Tom Westbrook here:
http://www.tomwestbrook.com/Photography/notebook.html
Best,
Helen
|
|
|
|
Ahmad Hasan
(K=4164) - Comment Date 5/22/2006
|
Thanks alot Helen I have many formulas now but which alkaline fixative do you think is better for general purposes and ,when developing the film is it necessary to use a hardening material during the process and at what step .
|
|
|
|
