Kodachrome 200 – Film for colour slides

K-14 was the most recent version of the developing process for Kodak's Kodachrome transparency film before its discontinuation (the last revision having been designated Process K-14M).[1] It superseded previous versions of the Kodachrome process used with older films (such as K-12 for Kodachrome II and Kodachrome-X).[2]

The K-14 process differed significantly from its contemporary, the E-6 process, in both complexity and length. Kodachrome film has no integral color couplers; dyes are produced during processing (each color in a separate step) by the reaction of the color couplers with the oxidised developer.[3]

Due to declining sales, Kodak discontinued production of all K-14 chemistry in 2009,[4] concurrently with Kodachrome 64 film. Dwayne's Photo, in Parsons, Kansas, operated the last K-14 line in the world, discontinued sales on 30 December 2010;[5][6][7] the last roll was processed on 18 January 2011.[8]

Steps

Kodachrome film schematic and exposure
Unexposed film cross-section
Exposure, showing sensitization of different layers according to red, green, and blue components of visible light

The cross-section of Kodachrome film consists of layers which are, from top-to-bottom: blue sensitive (of which the non-sensitized portions will be dyed yellow), yellow filter, blue-green sensitive (dyed magenta), blue-red sensitive (dyed cyan), acetate base, rem-jet anti-halation backing.[1][9]

The blue-green and blue-red sensitive layers are primarily sensitive to green and red light, respectively, but are sensitive to blue light as well. The yellow filter layer is added to prevent blue light from penetrating to these layers during exposure.[1]

K-14 processing cycle[10]
Step Action Schematic Description
1 Backing removal An alkaline bath softens the cellulose acetate phthalate binder. A spray wash and buffer removes the rem-jet anti-halation backing.
2 First Developer All exposed silver halide crystals are developed to metallic silver via a PQ (phenidone/hydroquinone) developer. The yellow filter layer becomes opaque because it has a combination of Lippmann emulsion (very tiny grains) and Carey Lea silver (metallic silver particles that are small enough that they are yellow rather than gray.)
3 Wash Stops development and removes the PQ developer.
4 Red light re-exposure through the base This makes the remaining undeveloped silver halide in the cyan layer developable.
5 Cyan developer The solution contains a color developer and a cyan coupler. These are colorless in solution. After the color developer develops the silver, the oxidized developer reacts with the cyan coupler to form cyan dye. The dye is much less soluble than either the developer or the coupler so it stays in the blue-red sensitive layer of the film.
6 Wash
7 Blue light re-exposure from the top This makes the remaining undeveloped silver halide grains in the blue sensitive layer (the yellow layer) developable. The now opaque yellow filter layers prevents the blue light from exposing the magenta layer (the green sensitive layer, which is also sensitive to blue light). It is important to avoid stray printing light exposing the film base of film.
8 Yellow developer Analogous to the cyan developer.
9 Wash
10 Magenta developer This contains a chemical fogging agent that makes all of the remaining undeveloped silver halide developable. If everything has worked correctly, nearly all of this silver halide is in the magenta layers. The developer and magenta coupler work just like the cyan and yellow developers to produce magenta dye that is insoluble and stays in the film.
11 Wash
12 Conditioner Prepares the metallic silver for the bleach step.
13 Bleach Oxidises the metallic silver to silver halide. The bleach (ferric EDTA) must be aerated. The former ferricyanide bleach did not require aeration and did not require a conditioner.
14 Fix Converts the silver halide to soluble silver compounds which are then dissolved and washed from the film.
15 Wash Washes the fixer out of the film.
16 Rinse Contains a wetting agent to reduce water spots.
17 Dry

The result is three different color records each with the appropriate dye, just like other color films. The original Kodachrome process in 1935 used dye bleaches and was a far more complex process; the dyes themselves were unstable and faded at high temperature. Although the formulae have changed over the years, the basic process steps have followed a similar pattern since the introduction of "selective re-exposure" Kodachrome in 1938.[11]: 163, 189 

References

  1. ^ a b c "Processing Steps – Processing Kodachrome Film (PDF)" (PDF). Eastman Kodak Company. 2000. Archived from the original (PDF) on 20 April 2003. Retrieved 1 March 2009.
  2. ^ "Archived copy" (PDF). Archived from the original (PDF) on 25 March 2020. Retrieved 16 August 2020.((cite web)): CS1 maint: archived copy as title (link)
  3. ^ "News Release". 27 June 2009. Archived from the original on 27 June 2009. Retrieved 29 April 2019.
  4. ^ Sulzberger, A. G. (29 December 2010). "For Kodachrome Fans, Road Ends at Photo Lab in Kansas". The New York Times. ISSN 0362-4331. Retrieved 29 April 2019.
  5. ^ "Last roll of Kodachrome developed". BBC. 30 December 2010. Retrieved 29 April 2019.
  6. ^ "Kodak Stopped Making This Film Nearly a Decade Ago. But It's About to Have an Unusual Comeback". Fortune. Retrieved 29 April 2019.
  7. ^ Press, Associated. "Kodachrome business swells in Parsons". The Wichita Eagle. Retrieved 29 April 2019.
  8. ^ Mannes, L.D.; Godowsky Jr, L. (July 1935). "The Kodachrome process for amateur cinematography in natural colors". Journal of the Society of Motion Picture Engineers. 25 (1): 65–68. Retrieved 24 August 2023.
  9. ^ "Process K-14 sequence with cross-sections" (pps). Retrieved 8 October 2016.
  10. ^ Pénichon, Sylvie (2013). "5: Dye Coupling (or Chromogenic) Processes". Twentieth Century Colour Photographs: The complete guide to processes, identification & preservation. London: Thames & Hudson. ISBN 978-0-500-51719-2.