The overview from one of the main sources of support from inside Kodak.
Kodak Dye Transfer Paper. They were not simple (nothing there ever was). The paper was almost triple thick photo-base. It was made from virgin fiber. Even the wrapping of the huge bails of fiber were discarded because they were addressed in black ink. The paper was the thickest that Kodak made. It had a subbing coat (a glue) to hold 2 laydowns of barite. Then two laydowns of gelatin-rich emulsion containing the thorium mordant and finally, an overcoat of clear emulsion to serve as a protection. When I say “gelatin-rich,” it is to differentiate it from normal paper emulsions that have a high “gelatin-to-junk” ratio. Junk is what the technicians call the plastic molecules that are routinely added to most film emulsions. Some emulsions contain very little gelatin at all. The goal is to do away with it completely because it is more expensive than the tiny bit of silver halide they now use. T-grain technology has allowed the emulsion to be reduced to the thickness of almost one micron.in the multi-layered films. — Frank McLaughlin, 2000.
There is some information about the process contained in patents [2,207,695 ]. There are also substitute, or alternative formulations for a mordant, or for making mordanted paper.
Mordant simply means the chemicals that will absorb, hold onto, the dyes so they don’t bleed, or wander. A well designed system picks dye and mordant to match so the color suits the overall system, keeping the palette in balance.
In addition to this resistance to physical damage the imbibition blank must yield transferred images having good density, contrast, and also high definition. This latter condition is obtained by retarding the bleeding or diffusion of the dyes in the colloid after transfer from the matrix by means of a mordant distributed in the colloid. Mordants are introduced in the colloid by mixing them into the coating dope or colloid prior to the coating of the blank or they may be introduced after manufacture of the blank and prior to the dye transfer operation by impregnation of the blank with a mordant solution. [ patent ]
search patents for: (imbibiton) (G03C7/25). pay attention to: Louis M. Condax.
- thorium nitrate TN <— original BUT hazardous in air
- aluminum sulfate AL <— common replacement for handmaders
- uranium ? nitrate
Uranium nitrate (cheaper). After the paper is dry I have to soak the paper in Sodium aluminate to create an insoluble salt on the surface so that the mordant doesn’t poison the matrix. Kodak used a thin layer of low bloom gelatin as a wicking layer between the mordanted gelatin and the matrix.