E-6 process. The E-6 process (often abbreviated to E-6) is a chromogenic photographic process for developing Ektachrome, Fujichrome and other color reversal (also called slide or transparency) photographic film.

Unlike some color reversal processes (such as Kodachrome K-14) that produce positive transparencies, E-6 processing can be performed by individual users with the same equipment that is used for processing black and white negative film or C-41 color negative film. The process is highly sensitive to temperature variations: a heated water bath is mandatory to stabilize the temperature at  for the first developer and first wash to maintain process tolerances.

History 

The E-6 process superseded Kodak's  E-3 and E-4 processes. The E-3 process required fogging with light to accomplish image reversal and produced transparencies that faded quickly.  The E-4 process used polluting chemicals, such as the highly toxic reversal agent borane tert-butylamine (TBAB).

Non-Kodak color reversal films introduced in the 1980s were compatible with the E-6 process, including variants of Fujichrome and Agfachrome, sold by Fujifilm and Agfa-Gevaert, respectively; one notable exception was Fujichrome 1600 Professional D, which was compatible with E-6 but used a customized PZ process for best results. The PZ process was similar to E-6, but used a different fog-suppressing chemical.

Process variations 
There are two versions of the E-6 process. Commercial laboratories use a six-bath chemical process. The 'hobby' type chemistry kits, such as those produced by Tetenal, use three chemical baths that combine the color developer and fogging (reversal) bath solutions, and the pre-bleach, bleach and fixer bath solutions. Rinses, washes, stop baths and stabilizer/final rinse (the final step of the process) are not counted as baths when describing both the conventional six bath and hobbyist three bath processes.

Six-bath process 

The structure of E-6 film has three separate light-sensitive layers; each layer is sensitive to a different group of wavelengths corresponding to red, green, and blue colors. When the film is exposed, each layer records a latent image based on its sensitivity. A yellow filter prevents blue light from exposing the green- and red-sensitive layers, which have some sensitivity to blue light.

Kodak Publication Z-119 provides instructions for various methods to carry out the E-6 process, including the use of continuous processors, roller-transport processors, rack-and-tank processors, batch processing, and rotary-tube processors; however, they largely share the same steps and recommendations for time and temperature with the exception of rotary-tube processors. The first developer, first wash, and reversal bath must be carried out in darkness.

Three-bath process 
Tetenal nearly closed in 2019, but was rescued through a management buyout, and relaunched its online store in 2020, operating as Tetenal 1847 GmbH. However, the chemical production part of Tetenal 1847 was spun off as Norderstedter Chemiewerke in 2022, which filed for bankruptcy in February 2023 and the three-bath process is no longer available.

See also 

 Replenishment (photography)

References

External links 
 Kodak Process E-6 Publication Z-119
 Kodak Q-LAB Process Control Handbook - more details than processing manual Z-119
 Kodak Professional First Developer Replenisher, Process E-6 (PDF)
 FujiFilm USA Product Bulletin Library technical data sheets
 E-6 Ektachrome DIY processing super-8 & 16mm.

Photographic film processes