This hardening fixing bath for use with films in hot weather should be used fresh, as it does not retain its hardening action.
|Hot water (125F or 52C)||2.5 L|
|Sodium Thiosulfate||960 g|
|Sodium Sulfite, anhydrous||60 g|
|Water to make||3 L|
|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From Ansco Formulas for Black and White Film by GAF, 1948 – Formulas are provided for historical reference.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.