C41

C-41 is the standard color negative film development process used for processing color photographic film. It was developed by Kodak and widely adopted by laboratories around the world in the late 20th century. The process yields a color negative with three dye layers corresponding to cyan, magenta, and yellow, which can be printed onto color photographic paper using the RA-4 printing process. The negative is intended to be projected or printed to produce accurate color reproductions when paired with conventional color chemistry.

Process overview: C-41 uses a fixed sequence of chemical baths to develop, bleach, fix, rinse, and stabilize the image. The typical sequence is color development, followed by bleaching, fixing, washing, and stabilizing. The development stage converts exposed silver halide into metallic silver and simultaneously forms the color dyes in the three emulsion layers. The subsequent bleach and fix steps remove metallic silver and unexposed silver halide, leaving a stable color negative. The stabilizer bath helps prevent deterioration and fading over time.

Temperature and timing: The process requires controlled temperatures, commonly around 38°C (100°F) for the developer, with timings that vary by film type and chemistry. Precise temperatures and dwell times are prescribed by the specific C-41 chemistry being used to ensure consistent results across different film stocks and lab equipment.

Usage and legacy: C-41 remains the de facto standard for developing consumer and professional color negative films, even as digital photography has grown. Many modern films are designed for C-41 compatibility, and the chemistry is widely available in local labs and home-processing kits.