E-4 process: Difference between revisions
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==History== |
==History== |
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[[File:Kodak Ektachrome IE 135-20 Infrared Slide Film.jpg|thumb|right|Kodak Ektachrome IE (infrared) film using E-4 process]] |
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E-4 processed film is color stable for about 30 years.<ref>{{Cite web | url=https://www.digitalrev.com/article/ektachrome-a-look-back | title=Ektachrome: A Look Back| date=25 January 2017}}</ref> |
E-4 processed film is color stable for about 30 years.<ref>{{Cite web | url=https://www.digitalrev.com/article/ektachrome-a-look-back | title=Ektachrome: A Look Back| date=25 January 2017}}</ref> |
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Revision as of 21:02, 24 August 2023
 | This article needs additional citations for verification. (April 2021) |
- See also Ektachrome for full details of Kodak E-series processes.
The E-4 process is a now outdated process for developing color reversal (transparency) photographic film, which was introduced in 1966.
Drawbacks
The process is infamous for two reasons:
First, it uses the highly toxic boron hydride-based reversal agent tertiary butyl-amine borane (TBAB).[a] Early releases of the consumer-sized version of the chemistry provided the TBAB in the form of a tablet. This was later changed to loose powder, likely as a countermeasure against inadvertent ingestion of the substance.
Second, the first two steps in the E-4 process are prehardener and neutralizer. When the prehardener is neutralized, a noxious gas, which has been likened to tear gas, is generated. Process E-6 films are hardened during manufacture, eliminating the prehardener step altogether and allowing them to be processed at 100 °F (38 °C).
Steps
The process is faster than E-3; whereas E-3 required 15 steps and up to 70 minutes from start to finish,[1][2]: 30–31 E-4 was completed in approximately 50 minutes over 13 steps.[3] E-4 runs at 85 °F (29 °C),[3] about 10°F (6°C) higher than E-3. The temperature tolerance is ±1°F for prehardener, ±1⁄2°F for the first developer, and ±2–5°F for all other steps.[3] The ME-4 process was a motion picture variation of the E-4 process.
The major change for E-4 was the inclusion of a chemical reversal agent, which permits processing of the film without the manual re-exposure/fogging step required by the predecessor E-1 / E-2 / E-3 processes.[1][3]
Total darkness is required during the first four development steps; normal room light can be used for the remaining steps.[3]
| Step | Time (min.) | Temp. | Description | ||
|---|---|---|---|---|---|
| 1 | Prehardener | 3 | 85 °F (29 °C) ±1°F | ||
| 2 | Neutralizer | 1 | 83–87 °F (28–31 °C) | ||
| 3 | First developer | 7 | 85 °F (29 °C) ±1⁄2°F | ||
| 4 | First stop bath | 2 | 83–87 °F (28–31 °C) | Solution not interchangeable with second stop bath (step 7) | |
| 5 | Wash | 4 | 80–90 °F (27–32 °C) | Running water | |
| 6 | Color developer | 9 | 83–87 °F (28–31 °C) | ||
| 7 | Second stop bath | 3 | 83–87 °F (28–31 °C) | Solution not interchangeable with first stop bath (step 4) | |
| 8 | Wash | 3 | 80–90 °F (27–32 °C) | Running water | |
| 9 | Bleach | 5 | 83–87 °F (28–31 °C) | ||
| 10 | Fixer | 6 | 83–87 °F (28–31 °C) | ||
| 11 | Wash | 6 | 80–90 °F (27–32 °C) | Running water | |
| 12 | Stabilizer | 1 | 83–87 °F (28–31 °C) | ||
| 13 | Dry | var. | <110 °F (43 °C) | ||
History
E-4 processed film is color stable for about 30 years.[4]
The process largely was phased out in 1976 with the introduction of the E-6 process, which is more environmentally friendly due to its lack of toxic chemicals. E-6 avoids the use of TBAB by adding a separate reversal bath containing the tin salt stannous chloride. The E-4 process has been discontinued since 1996; after 1976 it was used solely for Kodak IE color infrared film, due to a legal commitment by Kodak to provide process support for 30 years after introduction.
Notes
- ^ Not to be confused with tetra-n-butylammonium bromide, which also is abbreviated as TBAB.
References
- ^ a b Talbert, Michael. "Kodak Ektachrome Colour Transparency films". Photo Memorabilia. Retrieved 24 August 2023.
- ^ Kodak Ektachrome Film, Publication No. E-13. Eastman Kodak Company. 1955.
- ^ a b c d e f Wahl, Paul (April 1968). "Kodak's new E-4 kit: 50-Minute Cure for People Afraid to Develop Their Own Color Film". Popular Science. pp. 130–131.
- ^ "Ektachrome: A Look Back". 25 January 2017.
External links
Processing of older Ektachrome films (including Process E-4)
- Film Rescue USA and Canada
- Rocky Mountain USA
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