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 (slide) 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 100.0 °F (37.8 °C) for the first developer and first wash to maintain process tolerances.

The E-6 process superseded Kodak's E-3 and E-4 processes.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 a highly toxic reversal agent Tertiary Butyl-Amine Borane(TBAB).

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 bath solutions, and the pre-bleach, bleach and fixer bath solutions. The three-bath process has a discrete color developer step in between. However, the three-bath version of the process suffers from poor process control, with color shifts and color crossover, mainly because of insufficient bleaching, fixing or both in the bleach-fixer ("blix") stage.

The steps for developing color transparency films using process E6 are:

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