In contrast to tinting, toning is not the simple immersion of a film into a dye bath but involves a chemical reaction converting the silver image. In this reaction the neutral silver image in the emulsion of the positive film is replaced by one consisting of colored metal compounds. These were usually iron ferrocyanide (Prussian Blue) for blue, copper ferrocyanide for red/brown, silver sulfide for sepia or rarely uranium ferrocyanide for reddish brown. Toning had been used in still photography before. But since film was projected on the screen it required translucent toning compounds.
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Hongarije (FRA 1926, Anonymous). Credit: EYE Film Museum. Photographs of the tinted, toned and stencil colored nitrate print by Olivia Kristina Stutz, ERC Advanced Grant FilmColors.
- Virages sur films à support teinté Pathé, Film teinté lavande (virage bleu) lavender tinted stock with blue toning, the same image from a different copy of the book, combination of tungsten backlight with daylight toplight. Photograph by Barbara Flueckiger. Source: Didiée, L. (1926): Le Film vierge Pathé. Manuel de développement et de tirage. Paris: Pathé. [quote id='16']
- Photomicrograph, 25x. Credit: Norbert Wey, Institute of Pathology, University of Zurich.
- Photomicrograph, 50x. Credit: Norbert Wey, Institute of Pathology, University of Zurich.
- Photomicrograph, 100x. Credit: Norbert Wey, Institute of Pathology, University of Zurich.
- Toning samples from the Tinting and Toning Workshop by Ulrich Ruedel, Seminar "Materiality of Film" by Barbara Flueckiger and Bregt Lameris, Department of Film Studies, University of Zurich, in collaboration with Lichtspiel / Kinemathek Bern, David Landolf and Brigitte Paulowitz.
- Toning samples from the Tinting and Toning Workshop by Ulrich Ruedel, Seminar "Materiality of Film" by Barbara Flueckiger and Bregt Lameris, Department of Film Studies, University of Zurich, in collaboration with Lichtspiel / Kinemathek Bern, David Landolf and Brigitte Paulowitz.