Color Film Processing Types

Adapted from movie film stock, 35 millimeter film is the most common format.

While digital imaging has nudged film-based photography aside, film continues to hang on to a market share. The history of photography is dominated by silver halide systems and several remain in use a decade in to the 21st century. Chemical systems that were once complex and hard to control have been replaced with simple and easy to manage chemistry to meet the demands of the one-hour labs that dominate the film market.

K-14

Kodachrome slide film is the first mass-marketed color film, available first in 1935. The process has ten separate steps, not including washes and drying, with narrow tolerances for time and temperature. The results speak for themselves as Kodachrome film itself was manufactured until 2009, with processing continuing until early 2011. So loved are the results that a group of photographers is considering resurrecting the technology.

C-41

Color negative film is by far the most widely used film, and since the 1970s that has meant C-41 processing or its variations. Contrasting with K-14, C-41 consists of only three chemical steps: developer, bleach and fix. Dye couplers are incorporated into the emulsion layers of the film and dyes are formed during the developer process. The designation C-41 is Kodak's, and other manufacturers have compatible processes with different names, such as Fuji's CN-16 and AGFA's AP-70.

E-6

The only process to challenge K-14's supremacy in transparency film was E-6. Borrowing dye coupler technology from color negatives, E-6 has five chemical stages, not including washes. The comparative simplicity of E-6 as a process made it popular with magazine photographers, who shot transparency film and no longer had to wait days or weeks for Kodachrome film to return from the lab. One-hour processing equipment for E-6 is available.

ECN-2

The ECN-2 process began as a movie film process. Companies like Seattle Filmworks bought quantities of ECN-2 film, repackaged it and sold it under their brand. Because the ECN-2 process was hard to find, users would return the film to the manufacturer, who would then give a replacement roll with processed film, thus keeping the user returning. However, many consumers were not aware of the differences and if mistakenly processed in C-41 chemistry, the antistatic backing of the film was not completely removed.

References

• Kodak: K-14M Processing Steps
• Guide to Film Photography: Guide to Color Negative Film Processing
• CPAC Imaging: ECN-2 Processing