E-3 process

Ektachrome film structure and exposure

Structure

Sample exposure to various colors

Ektachrome 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.[1]

Films are processed at 75 °F (23.9 °C) with a tolerance of only ±0.5°F; exceeding these limits could cause color shifts.[2]^: 30–31 The steps are:

Early Ektachrome processes

Step			Schematic	E-1 (1946)[3]		E-1 (1955)[2]: 30–31  E-2 (1955)[3] E-3 (1959)[3]		Description
				Time (min)	Temp.	Time (min)	Temp.
	1	First developer		15	68 °F (20 °C)	10	75 °F (24 °C)	This is a conventional black-and-white developer, which develops the exposed portions as a negative.
	2	Stop bath / rinse		1	65–72 °F (18–22 °C)	1	73–77 °F (23–25 °C)
	3	Hardener		5–10	66–70 °F (19–21 °C)	3–10	73–77 °F (23–25 °C)
	4	Reversal exposure		varies (typically 5 sec/side)				The film is removed from the tank and thoroughly exposed with a bright light for either 5 seconds on each side, or each end of the reel is exposed for 15 seconds at a distance of 1 ft (0.30 m) from a No. 2 photoflood. This step sensitizes the remaining silver halide crystals for the colour developer. Replace in tank, though the lid was no longer required.
	5	Wash		5	65–72 °F (18–22 °C)	3	73–77 °F (23–25 °C)	Using running water
	6	Colour developer		25	66–70 °F (19–21 °C)	15	73–77 °F (23–25 °C)	This develops the now exposed silver bromide, and simultaneously activates the dye couplers in the three colour-sensitive layers of the film.
	7	Wash		5	65–72 °F (18–22 °C)	5	73–77 °F (23–25 °C)	Using running water
	8	Clear		5	66–70 °F (19–21 °C)	5	73–77 °F (23–25 °C)	To remove pink stains left by the colour developer. Solution saved for fixing bath (step 12). In the E-1 process, this is noted as a "clearing and fixing bath."
	9	Rinse		1	65–72 °F (18–22 °C)	1	73–77 °F (23–25 °C)	Using running water for at least 30 seconds, but not more than 90 seconds.
	10	Bleach		10	66–70 °F (19–21 °C)	8	73–77 °F (23–25 °C)	To convert all the developed silver into compounds that are made soluble in the fixer
	11	Rinse		1	65–72 °F (18–22 °C)	1	73–77 °F (23–25 °C)
	12	Fix		5	66–70 °F (19–21 °C)	3	73–77 °F (23–25 °C)	To remove all the developed silver. In the E-1 process, this is noted as a "clearing and fixing bath."
	13	Wash		10	65–72 °F (18–22 °C)	8	73–77 °F (23–25 °C)	Running water
	14	Stabilizing / Wetting agent rinse		1	65–72 °F (18–22 °C)	1	73–77 °F (23–25 °C)	Using Kodak Photo-Flo to remove water droplets
	15	Dry		not specified		varies	<110 °F (43 °C)	Same as for black-and-white films

The original Ektachrome process introduced in 1946 used similar steps with different durations; the total processing time was approximately 90 minutes.[4] It was renamed to E-1 when the E-2 process was introduced in 1955 for ASA 32 Ektachrome, followed by E-3 for ASA 50 Ektachrome in 1959.[3]

Films designed for E-2 and E-3 are prone to fading because of the instability of the color dyes.[5][6] The processes were phased out in 1974 in favor of E-4 (which was introduced in 1966), and two years later E-6 was introduced which remains in use to this day.

• Kodak specifications for hand mixing of chemistry

Processing of older Ektachrome films including Process E-3:

• Film Rescue USA and Canada
• Rocky Mountain USA