By 1935, Godowsky and Mannes and the Kodak research staff had developed a marketable subtractive color film for home movies. Kodachrome film was coated with three layers of ordinary black-and-white silver halide gelatin emulsion, but each layer was made sensitive to only one-third of the spectrum of colors—in essence, to red, green or blue. Special processing chemistry and procedures caused complementary cyan, magenta or yellow dye images to be generated in these layers as the black-and-white silver images were developed. After they had served their purpose, the silver images were chemically removed, so that the completed chromogenic film consisted solely of the three layers of dye images suspended in gelatin. is only partially accurate. All three layers were sensitive to blue light. The topmost layer was coated onto a "Carey-Lea silver" "filter" layer, which was a blue-light absorbing layer. This prevented blue light from reaching the two lower layers. It transmitted both red light and green light. The layer closest to the support was sensitive to both blue and red light. That is where the red light information was recorded. The layer above it was sensitive to both green and blue light. The top-most layer recorded the blue light information.