Kodachrome can be manufactured again. It has an elegant structure.
Kodachrome is probably the simplest successful design for dye-coupler color film, which is likely the reason it was the first produced. A wonderful essay concerning its development is in a chapter of the Time/Life book on color photography titled "Color". The principles behind Kodachrome are still in use today.
Basically the film had three layers of emulsion each sensitive to one of the primary colors of white light. These colors are blue, green and red. Emulsions with simple ingredients are sensitive only to blue light, so producing that layer of the film is easy. However every other kind of emulsion is also sensitive to blue light. To prevent the blue light from exposing the wrong layer the blue light has to be filtered out by a filter layer which allows only green light and red light to pass through it. Such a filter layer is yellow in color. Kodachrome could have used a yellow dye for this filter layer, but it adopted a brilliant innovation instead: the filter layer contained colloidal silver which just happens to be yellow in color. (There are recipes for the synthesis of colloidal silver dating back to c.1905). Since Kodachrome is designed so that all the silver in the film will be dissolved out during development, no special step is necessary to wash out this colloidal silver. The film under the filter layer will only be exposed to green and red light.
The layer of emulsion underneath the colloidal silver layer is sensitive to green light. Many dyes will make film sensitive to green light (erythrosine, for example, which is a food coloring). The final light-sensitive emulsion layer is sensitive to red light. PE, who held one of the patents on Kodachrome, identified the dye which sensitized Kodachrome to red light as Sand's SDA3057. This dye is stable enough to withstand the developing chemicals and still impart red sensitivity to the red light layer during the correct moment in the processing.
Kodachrome produces a positive color image in the form of a transparent slide or frame of movie film. To produce a positive image the film must be developed through a reversal process. So to start, the exposed film is bathed in a black and white developer to develop the latent image in each layer of the film. The top layer now has a negative corresponding to the image formed by blue light; the intermediate layer has silver metal grains corresponding to a negative of the image formed by green light; and the bottom layer forms a silver metal negative image of the red light exposure. The UNEXPOSED silver-halide grains still remain in each of the layers and are still light sensitive. They will be used to produce the colors.
All shades and hues produced by color film are made by a mixture of only three complementary colors. These are yellow, magenta and cyan (sky-blue). Color work requires us to be precise about shades and hues. Yellow is self explanatory. The color blue is the blue of a sapphire; darker than the sky--more of a royal blue. Sky-blue (cyan) is actually a mixture of blue and green light. Similarly, magenta is a mixture of red and blue light. The color red refers to shade very close to a ruby.
In the red sensitive layer, after the black and white development, all of the exposed grains sensitive to red light are now developed. The UNEXPOSED grains in this layer now correspond to the sections of the image made up of blue and green light. So if we develop just these grains and at the same time produce the color blue-green (cyan) then that layer will contain the correct positive component for the blue-green colors of the scene we photographed. We can develop these unexposed grains in the bottom layer by exposing them to red light, since they are still red light sensitive. Then we develop them with a liquid which produces cyan dye next to the silver-halide grains which the liquid develops. None of the unexposed grains in the green layer and in the blue layer will be developable since they are not sensitive to red light and therefore not exposed.
The unexposed grains of silver-halide in the blue light layer correspond to a positive image of the green and red light in the scene. Green and red light make the color yellow, so if we develop the unexposed grains in the top layer and at the same time lay down a yellow color, then that layer will contain a positive component of the scene corresponding to the yellow color. The blue light sensitive layer is exposed to blue light from the front of the film, exposing all the unexposed grains in that layer. The unexposed grains in the green light layer are protected from exposure by the intact colloidal filter layer above them. Thus, developing with a liquid which manufactures a yellow dye at the same time as it develops will only develop the grains in the top, blue-sensitive, layer of the film.
The only unexposed grains left in the film now are in the green light layer. These unexposed grains correspond to the red and blue areas of the photograph. The film may be exposed to daylight to expose these grains or a special chemical may be used to make these last remaining grains developable. They are developed with a liquid which produces a blue/red dye (magenta) when a grain is developed.
Finally all of the silver is dissolved out of the film using a well know liquid known as Farmer's Reducer--or something like it. This leaves only the yellow dye image; the magenta dye image; and the cyan dye image; a full-color photograph.
The liquid which manufactures the yellow, magenta and cyan dye molecules while the grains are being developed is called a "color developer". Generally it is an aqueous solution containing p-phenylenediamine (or a chemical like it). The lab adds to this liquid another chemical called a "dye coupler" to produce each specific color, yellow, magenta, cyan. Evans, Hanson and Brewer in chapter VII of "Principles of Color Photography" identify these color couplers as suitable for Kodachrome:
cyan
2,4-dichloro-1-naphthol
magenta
p-nitrobenzyl-cyanide
yellow
naphthoylacetanilide
