This hardening fixing bath for use with films in hot weather should be used fresh, as it does not retain its hardening action.

Solution 1

Hot water (125F or 52C) 2.5 L
Sodium Thiosulfate 960 g
Sodium Sulfite, anhydrous 60 g
Water to make 3 L

 

Solution 2

Hot water (125F or 52C) 1 L
Potassium Chrome Alum 60 g
Sulphuric Acid C.P. 8 ml

 

Slowly pour Solution 2 into Solution 1 while rapidly stirring the latter. Do not dilute for use. Do not dissolve the chrome alum at a temperature higher than 150F (66C). Always rinse films throughly before fixing. Normal fixing time 5 to 10 minutes at 68F (20C).

From Ansco Formulas for Black and White Film by GAF, 1948 – Formulas are provided for historical reference. They may not work well with modern films and papers. Some of the chemicals can be dangerous. As with all photographic processes, be careful.