The receiver sheet as described by Andre Rott and Edith Weyde contained nuclei - mainly of metals and metallic salts - suspended in the top layer of paper, or any substrate. When contacted by the processing chemical, and an exposed negative, the interchange of ionic silver, solvents, and sulfides occur in a rapid, battery-like process. Electrical charges, yes. The "electrolyte" is not that different than most alkaline batteries, except that is a developer and a fixer, too.
The silver halide in the exposed negative represents one "terminal" of the circuit. What is the second? In the fast-paced world of Diffusion Transfer Reversal, otherwise known as instant photography, it is the receiver paper, or more exactly, minute metals or metal salts and precursors, that form the second "electrode". Those who are familiar with battery technology are sure to ask "which is the cathode, and which is the anode?" It depends.
Below are two SEM images obtained just today that show the various receiver sheet layers. Stacked like a cake, but made of paper, then a baryta coat, then acid layers, a timing layer, a nucleation layer, and finally a top, or release layer (to prevent sticking). New55 FILM needs to make this or something like it. It's a daunting task as there are no recipes and even if there were, perhaps from patents and scientific papers, there'd still be a lot of process information. So we have over the last month started on the development of these layers, beginning with our visit to Colorado, where coaters capable of coating so-called "solvent coats" meaning, not water-based, but instead based on alcohols, acetone, or some other solvent. That was just the start: Now, every day, the coating team formulates at least one or two experiments, tests them, and decides on the next experiment.
The value of an SEM is hard to overestimate, and I would like to have one close, in our lab.
|Baryta, then cellulose acetate, acid layer and other layers|
|The nucleation layer. We barely see the tiny nanoparticles.|