Tanning Development and its Application to Dye Transfer Images^*

* Communication from the Laboratories of Technicolor Limited Londan

Abstract

A brood survey of many developing agents shows that almost all can be employed to produce tanned images although an oxidizing or an alkali bath after development is necessary for many of the Agents. Characteristic curves of relief images obtained by the use of a number of different developers followed by an oxidizing bath, show variations in contrast and relief “speed”, and also reveal considerable variations in the relief/silver ratio. Developer concentrations as well as the pH of the bath affect the result, the lower developing agent concentrations sometimes producing greater relief densities. Evidence has been provided that a stage of intermediate coupling can be recognised for both polyhydroxy and diamine type developing agents in which it appears that only a single link with the gelatin has been formed, cross-linking requiring a second stage of coupling. It is thought that the first oxidation product of development is a compound of the developing agent with an amino group of the gelatin molecule, the combination occurring at the ortho position with respect to the -OH or NH₂ group of the developer. Adsorption of the developing agent to functional groups in the gelatin possibly provides the conditions necessary for tanning develobment.

Notes

* Communication from the Laboratories of Technicolor Limited Londan