SPUR Ultrafix A is an alkaline fixer concentrate, 1 litre, for film and paper.
What it is for
An alkaline fixer is chosen for two reasons. First, staining developers: acid would destroy their stain. Second, baryta paper: it washes free of an alkaline fixer faster and more thoroughly, and a badly washed print yellows over the years.
How to dilute it
The solution is replenishable — kept and reused, with development time extended as it exhausts. Keep count of the films put through it; that is the only way to avoid an underdeveloped roll at the end of its life.
Storage
Sealed concentrate keeps well but dislikes air: the emptier the bottle, the faster it oxidises. Decant the remainder into a smaller bottle, or displace the air — that is what gets a concentrate to its last measure.
How it compares
Its counterpart is Ultrafix N, slightly acid, in this same catalogue. The nearest equivalent in purpose is Moersch ATS Alkaline.
