 Silver-halide crystals are naturally sensitive to blue light, so the blue layers are on the top of the film and they are followed immediately by a yellow filter, which stops any more blue light from passing through to the green and red layers and biasing those crystals with extra blue exposure.Next are the red-sensitive record (which forms cyan dyes when developed); and, at the bottom, the green-sensitive record, which forms magenta dyes when developed.Each color is separated by a gelatin layer that prevents silver development in one record from causing unwanted dye formation in another.