In all friendlyness a small addition for historical accuracy, Eastman-Kodak had made black-and-white ciné films with a soot-gelatin back layer from February 1931 on.
Charles Edward Kenneth Mees, History of Professional Black-and-White Motion-Picture Film, Journal of the SMPTE, October 1954: “Panchromatic Cine-Kodak Film, Type 5255, was placed on the market in 1928. The camera film was first supplied for daylight loading with a paper leader. Many experiments were made on the use of an opaque backing to avoid the troubles involved in the use of the paper leader. Finally, in 1931, a jet-black backing was made which gave the necessary protection to the film and which was removed in the processing machines. Supersensitive Cine-Kodak Panchromatic Type 5256 was introduced early in 1931, and this was replaced in 1939 by Super-X Cine-Kodak Panchromatic Film having the same type number, 5256, which is a current product. ( . . . ) The future of motion-picture photography, however, involves the use of color, and the principal advances in motion-picture films will depend upon the improvement of the materials and processes used for color photography.”