Processing Ektachrome E-4 film
Ektachrome is Kodak colour reversal (transparency or slide) film first introduced in 1946 and still produced by Kodak Alaris. The emulsion and the development process went through several updates from the original technology later named process E-1 to the current E-6 process used by both Fuji and Kodak, the last remaining slide film manufacturers.
I recently acquired several rolls of exposed Ektachrome E-4 film and started researching the options for its development. While earlier processes E-1 to E-4 were quite similar and with some adjustments could be processed in E-4 chemistry, the modern E-6 process is radically different: it uses different colour couplers, requires different chemistry and runs at a much higher temperature. Any attempts at cross-processing E-4 film in standard E-6 process are guaranteed to fail as the earlier Ektachrome emulsions are very soft and will melt at 38 °C, the standard temperature for E-6. Even if you develop at lower temperature the results would probably be disappointing.
Earlier Ektachromes especially E-3 and E-4 could be processed at home by the photographer and the kits were available from Kodak. As modern E-6 process superseded E-4 in the late 1970s the production of E-4 kits for home use must have stopped as well. Even if you manage to find one of those 40-year-old kits today the chances of it still being usable are very slim.
The procedure for the home-processing kit includes the following steps:
| Step | Time, min | Temperature, °C |
|---|---|---|
| 1. Pre-Hardener | 3 | 29.5 ± 0.5 |
| 2. Neutraliser | 1 | 28 - 31 |
| 3. Wash | 1 | 28 - 31 |
| 4. First Developer | 6 | 29.5 ± 0.25 |
| 5. First Stop Bath | 2 | 28 - 31 |
| 6. Wash | 4 | 27 - 32 |
| 7. Colour Developer | 15 | 28 - 31 |
| 8. Second Stop Bath | 3 | 28 - 31 |
| 9. Wash | 3 | 27 - 32 |
| 10. Bleach | 5 | 28 - 31 |
| 11. Fixer | 4 | 28 - 31 |
| 12. Wash | 6 | 27 - 32 |
| 13. Stabiliser | 1 | 28 - 32 |
In 2000 Kodak released publication CIS-111 describing E-4 processing solutions. So theoretically, one can prepare the authentic E-4 chemistry using the original formulas. I doubt that anyone would want to do it though. The solutions contain formalin, succinaldehyde and tertiary butylamine borane (TBAB) which are highly toxic and hard to source in most countries.
Two alternative formulas for E-4 were published by Patrick Dignan in his How to Compound Simplified Color Processing Formulas. In the book they are called "Modified E-4" and "Simplified 18 minute E-4". The "Simplified" version was designed to speed up processing and takes some shot-cuts like replacing the pre-hardener and neutralizer steps with the hardener bath after first development. The official and "Modified" formulas are compared below.
Pre-Hardener
The formulas are to make 1 litre of solution. The order in which the chemicals should be added in the solution was changed for easier comparison.
| Component | Kodak | Modified E-4 |
|---|---|---|
| Succinaldehyde Disodium Bisulfite | 10.00 g | - |
| Sodium sulfate, anhydrous | 147.00 g | 140 g |
| Aminoacetic acid | 1.00 g | - |
| Sodium bromide | 2.00 g | - |
| Potassium bromide | - | 16 g |
| Sodium acetate, anhydrous | 15.00 g | - |
| Formalin | 28.35 g (37%) | 30 ml (40%) |
| Acetic acid, glacial | 5.24 g | - |
Neutralizer
The step is required to remove the hardener(s) from the emulsion.
| Component | Kodak | Modified E-4 |
|---|---|---|
| Hydroxylamine sulfate | 12.60 g | 18.0 g |
| Sodium Bromide, anhydrous | 11.90 g | 20.0 g |
| Acetic acid, glacial | 7.00 g | 7.0 g |
| Sodium Hydroxide, 50% solution | 9.6 g | - |
| Sodium sulfate, anhydrous | 23.5 g | 50.0 g |
| 3-MethylBenzothiazolium p-toluenesulfonate | 0.021 g | - |
| Sodium Acetate | - | 7.0 g |
First developer
The first developers are quite different. The Kodak formula is close to D-67 Metol-Hydroquinone developer used in B&W reversal process, see Kodak Publication J-1, page 50. The modified developer uses Phenidone-Hydroquinone. Again, the order was changed for the ease of comparison.
| Component | Kodak | Modified E-4 | Kodak D-67 |
|---|---|---|---|
| Sodium sulfite, Anhydrous | 39.00 g | 50 g | 90.0 g |
| KODAK ELON Developing Agent | 5.00 g | - | 2.0 g |
| Phenidone | - | 0.35 g | - |
| Hydroquinone | 5.90 g | 6.0 g | 8.0 g |
| Quadrafos | 2.00 g | - | - |
| Sodium hexametaphosphate | - | 2.0 g | - |
| Sodium carbonate, monohydrated | 28.1 g | 35.0 g | 52.5 g |
| Sodium bromide, anhydrous | 1.50 g | - | - |
| Potassium bromide | - | 2.0 g | 5.0 g |
| Potassium iodide (0.1% solution in water) | 9.00 ml | 6.0 ml | - |
| Sodium thiocyanate | (51% solution) 2.59 g | 1.3 ± 0.1 g | 3 ml |
| Sodium hydroxide | - | 2.0 ± 0.5 g | - |
The development time is 6 min for both Kodak and Modified E-4 developers at 29.5 ± 0.25 °C.
Stop Bath
Stop baths are used after the first developer and the colour developer. Two solutions must be prepared using the same formula, reuse of the first stop bath is not recommended.
| Component | Kodak | Modified E-4 |
|---|---|---|
| Acetic acid, glacial | 28.5 g | 15.0 g |
| Sodium hydroxide, granular | 1.75 g | - |
| Potassium Alum | - | 20.0 g |
| Sodium Sulfate, anhydrous | - | 20.0 g |
| Sodium Acetate | - | 15.0 g |
Colour developer
The modified E-4 formulas do not include the reversal agent and re-exposure is used instead after the first stop bath following a wash for 4 minutes. 15 seconds exposure for each side of the film is recommended using Kodak Photoflood #2 as a light source.
| Component | Kodak | Modified E-4 |
|---|---|---|
| Quadrafos | 5.0 g | - |
| Benzyl alcohol, photograde, inhibited | 3.25 g | (35% solution), 10 ml |
| Sodium sulfite, anhydrous | 7.60 g | 5.0 g |
| Potassium iodide 0.1% solution | 28 ml | 10 ml |
| Sodium bromide, anhydrous | 0.8 g | - |
| Potassium bromide | - | 0.2 g |
| Sodium hydroxide, 50% solution | 4.1 g | (100%), 8.0 g |
| Ethylenediamine, 99% | 3.0 g | - |
| Ethylenediamine sulfate | - | 7.6 g |
| Tertiary butylamine borane, powder | 0.070 g | - |
| Trisodium phosphate, dodecahydrated, crystals | 36.0 g | 40.0 g |
| Citrazinic acid | 1.35 g | 1.3 g |
| Color Developing Agent CD-3 | 10.5 g | 12.0 g |
| Tetrasodium EDTA | - | 3.0 g |
The 35% solution of benzyl alcohol in the Modified E-4 colour developer is made of 35 ml benzyl alcohol, 45 ml diethylene glycol and 20 ml of water.
The development time is 15 min for the Kodak developer and 9 min for the modified formula.
Bleach
The modified formula is given for stock solution that is to be diluted 1 part stock to 3 parts water. The working solution should be discarded after use. The concentration in the working solution is given in the table below.
| Component | Kodak | Modified E-4 (working solution) |
|---|---|---|
| Sodium thiocyanate, 51% solution | 14.7 g | 6.25 g |
| Potassium ferricyanide, anhydrous | 90.0 g | 75.0 g |
| Sodium bromide, anhydrous | 22.5 g | - |
| Potassium bromide | - | 18.75 g |
| Disodium phosphate, anhydrous | 19.5 g | (heptahydrated) 11.25 g |
| Monosodium phosphate, monohydrated | 7.5 g | (anhydrous) 3.0 g |
Kodak recommends longer bleaching time (5 min compared to 3 min in the Modified E-4).
Fixer
Kodak publication does not include the formula for the fixer and recommends to use Kodak E-6 fixer. The stock fixer solution in the Modified recipe is made of 1 litre of 60% ammonium thiosulfate solution with 100 g of potassium bisulphite. The working solution is prepared by mixing 1 part stock in 4 parts water. The fixer is used once and then discarded.
Stabilizer
Kodak uses 6 ml of formalin (37.5%) and 0.14 ml of Renex 30 surfactant in 1 litre of water. Renex 30 is a trade name for Polyoxyethylene (10) Tridecyl Ether. The Modified formulation is made of 3 ml formalin (40%) and 10 ml of Kodak Photo-Flo.
Implementing the process
While the original Kodak formulas are out of reach for most home darkroom users, the Modified variant is certainly doable provided you can source specialized chemicals like citrazinic acid and CD-3 that are not commonly available from photographic suppliers. Despite its toxicity, formalin is still widely used, and you should be able to acquire it possibly as a more dilute solution. Benzyl alcohol is also quite common but might be a bit expensive if you buy pharmaceutical grade.
Preparing the full set of E-4 solutions might be a costly exercise unless you are used to mixing your own chemistry and already have most of the required chemistry or have a large stock of Ektachrome film to process. For just several rolls of mystery film a more practical approach is required.
Alternatives for pre-harderning
Formalin (and succinaldehydes) is not the only substance that can be used to harden film emulsion. Kodak publications provide several other formulas including Kodak Hardening Bath SB-4 (Kodak J-1, page 37):
| Component | Quantity, g |
|---|---|
| Potassium Chrome Alum, crystals (dedecahydrated) | 30.0 |
| Sodium Sulfate, anhydrous | 60.0 |
In the Book of Formulas for Eastman Professional Films and Plates published in 1938 this hardener is called "Tropical" and is recommended for use in the temperature range from 24 °C to 32 °C which suits our application. The original instruction is to use after developing and before fixing, but it should work equally well as a pre-hardener followed with a thorough wash.
Even simpler is the Chrome Alum Hardening Bath (Kodak Formula SB-3) consisting of 30 grams Potassium Chrome Alum in 1 litre of water. It is also recommended for use "in hot weather". The hardening time is 3 minutes.
The latter solution was suggested by PhotoEngineer on Photrio forum. Neutralizer bath is not required for these hardeners, but the film should be washed before development.
Mixing the First Developer
It should be possible to use E-6 first developer at a low temperature in E-4 process. The development time would need to be adjusted, probably by trial and error.
Mixing the first developer from raw chemicals should not be a problem for anyone who makes their own B&W chemistry. There is some ambiguity regarding the order in which the chemicals should be mixed. Kodak CIS-111 publication emphasizes that the components should be added in the order given in the formula, which is a standard convention. That means that the full amount of sodium sulfite should be dissolved before adding metol. This is different from all other Metol-Hydroquinone formulas in which metol is added first. Photographer's Formulary in the instructions for their B&W reversal processing kit give a first developer formula similar to Kodak D-67 and include the following note:
Add a pinch of sodium sulfite; this amount retards the initial oxidation of the metol. If more sulfite is added at this point the metol will not dissolve.
Also, neither Quadrafos nor sodium hexametaphosphate should be required if distilled water is used to prepare the solution.
Stop Bath
Kodak stop bath for E-4 differs from common formulas as it calls for sodium hydroxide. It is not clear why this should be needed.
Options for Colour Developer
Colour developers similar to E-4 were used in other Kodak processes including C-22 and VNF-1, both discontinued long ago. E-6 colour developer would probably be the closest alternative available today. Kodak formulas for their single use E-6 kit are included in their US patent 5,948,604. Fuji process is described in US patent 6,720,134. These patents are now expired.
A number of alternative formulations are also known. A detailed description of the process is published by Alexey Shadrin in 1992. The book (in Russian) is available online from the publisher. Patrick Dignan's book contains E-6 recipes and discusses experiments on running the process at lower temperatures. E-6 Processing Changes that Change Color Balance is another useful piece of information found in the same book (page 57). British Journal of Photography Annual published E-3, E-4 and E-6 formulas for a number of years.
The comparison of Kodak E-4, Kodak E-6, Fuji E-6 and Alexey Shadrin's formulas for the colour developer is given in the table below. These E-6 kits have separate colour reversal baths based on stannous chloride, while the E-4 formula includes the notorious TBAB in the developer. Kodak E-6 solutions are given in the patent as Part A and Part B solutions in the concentrated form. The working solution is prepared by mixing 200 ml of part A and 47 ml of part B and adding water to 1 litre, that is the amounts for Part A concentrate should be divided by 10 and Part B by 21.2 to calculate the equivalent amount in the working solution.
| Component | Kodak E-4 | Kodak E-6 | Fuji E-6 | Shadrin's E-6 |
|---|---|---|---|---|
| Quadrafos | 5.0 g | - | - | - |
| Benzyl alcohol, photograde, inhibited | 3.25 g | - | - | - |
| Sodium sulfite, anhydrous | 7.60 g | 2.99 g | 7.0 g | 0.8 g |
| Potassium iodide | (0.1%) 28 ml | 0.0147 g | 0.090 g | (1%) 2-3 ml |
| Sodium bromide, anhydrous | 0.8 g | 0.1 g | - | - |
| Potassium bromide | - | - | 1.0 g | 0.5 g |
| Sodium hydroxide, 50% solution | 4.1 g | 1.375 g | (100%) 12.0 g | - |
| Potassium hydroxide, 45.5% solution | - | 27.86 g | - | to PH 11.6-11.7 |
| Ethylenediamine, 99% | 3.0 g | - | - | - |
| Tertiary butylamine borane, powder | 0.070 g | - | - | - |
| Trisodium phosphate, dodecahydrated, crystals | 36.0 g | - | 36.0 g | 32.0 g |
| Phosphoric acid, 75% solution | - | 8.9 g | - | - |
| Citrazinic acid | 1.35 g | 0.279 g | 0.5 g | 0.8 - 1.3 g |
| Color Developing Agent CD-3 | 10.5 g | 8.34 g | 10.0 g | 11.3 g |
| 2,2'-Ethylenedithiodiethanol (Tegochrome 22) | - | 0.36 g | 1.0 g | - |
| Dequest 2000, 50% solution | - | 2.05 g | - | - |
| Sodium metabisulfite | - | 0.30 g | - | - |
| Dequest 2006 | - | 2.0 g | - | |
| Sodium hexametaphosphate | - | - | - | 0.5 g |
| 6-nitrobenzimidazole | - | - | - | 0.05 g |
| Phenylhydrazine sulfate | - | - | - | 0.03 g |
Theoretically, it should be possible to add 3.25 g of benzyl alcohol to E-6 colour developer from a kit and use it as a substitute for E-4 colour developer at the specified temperature of 29.5 °C. Since the concentrations of the developing agent and citrazinic acid are different in E-4 and the substitute solution development time might need to be adjusted from the recommended value of 15 minutes.
A note in Patrick Dignan's book (page 58) discusses experiments with running E-6 process at a lower temperature of ~24 °C. Recommended time for E-6 colour development at 24 °C is 21 minutes. In another experiment the film was left in the colour developer at room temperature for 24 hours without affecting the quality of the results!
Reversal Solution
In popular E-6 kits like Tetenal Colortech and CineStill Cs6 reversal chemicals are included in colour developer solution which is mixed from a two-part concentrate. Most likely, stannous chloride is used as a reversal agent and added to Part A concentrate while Part B contains CD-3 with some sodium metabisulfite as a preservative, see Tetenal and Cinestill Safety Data Sheets. Fuji Hunt E-6 chemistry set for professional photo labs also provides reversal and colour development solutions combined. It is not clear if E-6 reversal agent will work with Ektachrome E-4 film without experimentation.
A safer option would be to use light re-exposure (fogging) as was done in E-3 process but this would require separate reversal and colour developer solutions. Original E-6 7-part kits are available from Bellini and ars-imago in Italy and Co-op Photo Chemists in Russia. These kits are very well suited for preparing E-4 substitute chemistry. Sourcing the kits outside Europe might be problematic due to shipping restrictions on liquid chemicals.
Ferricyanide Bleach
PhotoEngineer mentions in this post that ferricyanide bleach must be used for E1-E4 films to properly form the dyes and can not be replaced with E-6 process bleach.
Which Fixer?
Modern E-6 kits combine bleach and fixer into one solution made of 3-part (CineStill) or 2-part (Tetenal) concentrate. Thus, either a 7-part kit with separate fixer solution is required or it has to be prepared from raw chemicals using one of the formulas in the table below, or that provided by the Modified E-4 process.
| Component | Kodak E-6 | Fuji E-6 |
|---|---|---|
| Ammonium thiosulfate | (56%) 87.17 g | 80.0 g |
| Ethylendiaminetetraacetic acid | 0.41 g | - |
| Sodium metabisulfite | 4.98 g | - |
| Sodium sulfite | - | 5.0 g |
| Sodium bisulfite | - | 5.0 g |
| Sodium hydroxide | (50%) 1.39 g | - |
Stabilizer Options
The original E-4 formula uses formalin in the stabilizer solution. In Kodak and Fuji E-6 formula it is replaced with PROXEL GXL biocide (solution of 1,2-benzisothiazolin-3-one in dipropylene glycol and water). Ron Mowrey (PhotoEngineer) in his posts on C-22 and colour stabilizers explained that formalin is required in the stabilizer solutions to prevent dye fading.
References
- Kodak Publication CIS-111. Formulas for Process E-4 Solutions. 2000 (PDF)
- Kodak Publication J-1. Processing Chemicals and Formulas for Black-and-White Photography. 1977 (PDF)
- Patrick Dignan. How to compound ... Simplified Color Processing Formulas. (PDF)
- Шадрин А.Е. Процесс Е-6: Лабораторная обработка цветных обращаемых фотоплёнок типа Эктахром. 1992 (PDF).
- Concentrates and Working Solution for E-6 Color Developer Based on Kodak's US5948604A
- Grant Haist. Modern Photographic Processing. Volume 2. 1979 (PDF available on z-lib.org)
- George T. Eaton. Photographic Chemistry in Black and White and Color Photography. 1966 (PDF)
- The British Journal of Photography Annual 1981, pages 198-201 (PDF)
- Derek Watson. Chrome Brew - making your own E-6 from raw chemicals