fixer
Kodak F-5 acid hardening fixer
Handle chemistry safely
Wear gloves and eye protection, work with good ventilation, and read the supplier’s safety data sheet before use. Hazard information here is a summary, not a replacement for it. Dispose of all photographic chemistry correctly, in line with local laws and your local authority’s guidance. Never mix waste solutions, and check the supplier’s safety data sheet before disposing of anything.
Ingredients
| Sodium thiosulfate pentahydrate | 240 g |
| Sodium sulfite (anhydrous) | 15 g |
| Acetic acid (28%) | 48 mL |
| Boric acid (crystals) | 7.5 g |
| Potassium alum (dodecahydrate) | 15 g |
| Water to make | 1.0 L |
Notes
General-purpose acid hardening fixer, mixed in warm water in the listed order. Use crystalline boric acid, because the powder dissolves poorly. Kodak gives 5–10 minutes for films and prints. The hardener can also be kept as a separate stock (F-5a).
Source
Processing Chemicals and Formulas for Black-and-White Photography (Kodak Publication J-1), 7th edition, Eastman Kodak Company (1977), p. 38
Amounts as published. Chemical forms (anhydrous, monohydrate and so on) change the weights, so match the form listed.