Non-substantive is a term used to describe colour film in which the colour couplers are not incorporated within the emulsion layers of the film itself. Instead, these couplers are introduced during the chemical processing stage, where they react to form the final colour image.
This approach differs from modern integral colour films, where the couplers are built directly into the emulsion. Non-substantive processes were used in earlier colour photography systems and are important in understanding the evolution of colour film technology and photographic chemistry.