|Hot Water (125F or 52C)||500 ml|
|Ferric Ammonium Citrate||8 g|
|Acetic Acid (28%)||265 ml|
|Water to make||1 L|
Solution should be prepared with distilled water if possible. If enameled iron trays are used, no chips or cracks in the enamel should be present or spots and streaks may appear in the print.
Prints for blue toning should be fixed in plain, non-hardening hypo bath (which should be kept at a temperature of 68F or under to avoid undue swelling). When prints have been fully toned in the above solution, they will be greenish in appearance, but will be easily washed out to a clear blue color when placed in running water.
The depth of the blue toning will vary somewhat with the quality of prints toned in it, light-toned prints generally toning to lighter blues. Some intensification of the print usually occurs in toning; consequently, prints should be slightly lighter than the density desired in the final toned print.
Wash water should be acidified slightly with acetic acid since the blue tone is quite soluble in alkaline solutions and is considerably weakened wieh wash water is alkaline. Pleasing variations in the tone can be obtained by bathing the washed prints in a 1/2% solution (5 grams per liter) of borax which produces softer, blue-gray tones, the extent depending on the length of treatment.
From Ansco Formulas for Black and White Film by GAF, 1948 – Formulas are provided for historical reference.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.