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From Ansco Formulas for Black and White Film by GAF, 1948 – Formulas are provided for historical reference.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.
