Double Toning of Motion Picture Films

A motion picture image with green shadows and blue halftones can be prepared by toning the image blue in the usual toning solution, fixing in hypo, washing, and then re-toning followed by immersion in a solution of a basic dye. In this way the first toning bath converts the silver image to a mixture of Prussian blue and silver ferrocyanide, the reaction going to completion in the halftones but incompletely in the shadows so that some of the silver is unaffected. The silver ferrocyanide is removed in the hypo solution leaving an image consisting of pure Prussian blue in the halftones and a mixture of this substance and silver in the shadows. On re-immersion in the blue toning bath, the silver in the shadows is again converted to a mixture of Prussian blue and silver ferrocyanide which latter substance is a mordant for basic dyes, so that on immersion in a dye solution the dye is absorbed only to the shadows.

Print ISSN

0097-5834

Published

1931-01

Content type

Original Research

DOI

10.5594/J16628