Gasparcolor was the first three-color multi-layer monopack film available for practical use. It was a double-coated print film with a cyan layer on one side and two layers dyed magenta and yellow on the other side (see illustrations).
Dufaycolor was a regular line screen process whereby the incident light was filtered through a pattern of tiny color patches created by lines in red, green and blue, the so called réseau.
“In 1930 Mannes and Godowsky were invited to join the staff of the Kodak Research Laboratory, where they concentrated on methods of processing multilayer films, while their colleagues worked out ways of manufacturing them. The result was the new Kodachrome film, launched in 1935. Three very thin emulsion layers were coated on film base, the emulsions being sensitised with non-wandering dyes to red, green and blue light, the red-sensitive layer being at the bottom.” (Coe, Brian (1978): Colour Photography. The First Hundred Years 1840-1940. London: Ash & Grant, pp. 121 ff.)