E6 is the colour-reversal process used to produce slides; you can buy chemistry kits to do it at home. It is strongly recommended that you become familiar with black and white processing before attempting colour. If you also shoot colour negative, it would be good idea to become proficient in C41 processing before E6 simply because mistakes made with those chemicals will be cheaper, and you can make sure your temperature stability is good before working on the expensive soup.
If your time is free, you can develop E6 film for about $2/roll using off-the-shelf kits, which is appealing if you shoot a lot of colour and your local lab charges $10-15 per roll for E6 develop-only.
The E6 process is carried out at 37.8C and requires tight temperature control to prevent colour shifts and crossover. Subtle colour shifts in a slide are uncorrectable because there is no postprocessing (e.g. printing of a C41 negative) stage in which to correct the colour unless you plan to scan.
E6 is more complex than negative processing because a reversal stage is required to produce a positive image. Considering exposure = E and film density = D,
That's a gross over-simplification but it should make it clear that E6 needs to implement a subtraction function chemically.
The process steps are:
Each step is explained below; chemicals from all stages (except for wash water) are re-used several times, therefore they should be carefully captured with a view to preventing cross-contamination after each bath.
Consult the instructions with your kit for processing times; they should be constant regardless of the film type except when pushing or pulling and when reusing the developer.
The film is pre-washed using process-temperature water, which serves the following purposes:
A total of at least 5:00 washing time should be used, with two changes of water, e.g. a 2:00 wash followed by a 3:00 wash. All wash-water should be at process temperature (37.8C).
At this stage, the film is in its exposed but undeveloped state. There is a quantity of activated silver halide ("A") present in each layer of the film that is proportional to exposure, i.e. A = E.
The first developer is a simple black-and-white developer, which produces a monochrome negative image in each layer (one layer per primary colour) of the film. Temperature control and timing of this stage is critical in order to obtain correct contrast and colouring of the final result.
Being a B&W developer, this stage converts activated silver halide into metallic silver, i.e. all of the A is converted to D, therefore D = E and A = 0 after this stage. The image is the same as an un-fixed classic B&W negative at this point.
This stage is responsible for stopping development activity and removing all developer from the film.
If we consider the total quantity of halide (H) in the fresh film to be 1, then after first-developer, H = 1 - D = 1 - E
This bath is a chemical exposure agent, it is functionally equivalent to exposing the film to a huge quantity of light. All of the silver halide that was undeveloped by the first developer (H) will be activated at this stage, so that A = 1 - D = 1 - E.
This reaction proceeds to completion so timing and temperature are not critical, however it is a good idea to maintain 37.8C during this bath so that the colour developer operates at the correct temperature.
The colour developer (CD-3) will develop all of the newly-activated (by reversal) silver halide and have no effect on the already-developed metallic silver from the first developer. The by-products of development interact with dye-couplers in each layer of the film to produce dyes at the locations where development occurs, therefore the density of dye will be proportional to the quantity of activated halide developed at each point in the film.
The process is carried out to completion, though temperature regulation (and pH of the developer solution) is somewhat important for preserving accurate colour.
This stage produces D(dye) = A = 1 - E and D(silver) = A = 1 - E. Once complete, all of the silver halide in the film has been developed, either by the first developer or the colour developer, so we have a total density (considering both metallic silver and dyes) of D = 1 + 1 - E.
The pre-bleach stage has no direct effect on the image, but it contains components responsible for long-term preservation of the film, protection of the dyes from the bleach and for priming the bleaching process. It depends on carry-over of colour developer, therefore there should be no wash step between colour development and pre-bleach.
This bath is process-to-completion; timing and temperature are not critical.
The bleach stage is responsible for converting all metallic silver back into silver halides so that it may be removed by the fixer. This reaction is performed to completion, with no strict requirements on timing or temperature - a couple of extra minutes won't hurt and might be a good idea if the bleach is reaching its rated capacity.
Once this stage is completed, we have H = 1, D(silver) = 0 and D = D(dye) = 1 - E, i.e. a positive image made up of dyes.
This stage (washing with water) is responsible for removing bleach from the film. It is not strictly required, however bleach attacks fixer and reduces its shelf life, therefore this wash stage is recommended in order to preserve chemistry.
I use a wash of approximately 4 minutes (continuous agitation) with 5 changes of water.
The fixer is an ammonium thiosulfate-based rapid fixer; it removes all silver halides from the film. This reaction is performed to completion, with no strict requirements on timing or temperature - a couple of extra minutes won't hurt and might be a good idea if the fixer is reaching its rated capacity.
Once this stage is complete, there should remain no silver in the film, either in metallic or halide form.
This wash stage is responsible for removing all fixer from the film so that it may be archivally stable.
Using the rotary processor, I change the water about 8 times in 10 minutes (longer washes near the end, shorter-washes near the beginning), using 1.5-2x as much as is necessary to cover the film. Always have at least one change of water be the max rated capacity (generally 1L for Jobo) of the tank.
The final rinse contains surfactants (to help prevent spots while drying) and some preservatives to help with stability of the film. DO NOT WASH the film after it has been in the stabiliser bath; the stabiliser must dry onto the film.
Stabilisers, final rinses and the surfactants they contain (similar to Photoflo) have a reputation for gumming up tanks, spirals and funnels (Jobo Lift). I never put stabiliser through the Jobo Lift from a perhaps-irrational fear that it will be difficult to wash out and likewise don't bother putting it in the tanks either. Instead, I transfer each spiral (after the wash) to a 2L plastic container full of final rinse and let it sit there for the required time before draining and drying the film.
After each spiral has been unloaded, it (the spiral, NOT the film) is washed with hot (50-60C) water to remove all traces of final rise and prevent contamination of later processes using the same spiral.
DO NOT PANIC here; the film will look milky, slightly-purple and of low saturation while wet. It will achieve its glorious appearance only once completely dry.
Dry the film in preferably-filtered air. If dust reaches the film while wet, it will sink into the emulsion and never be removed, whereas dust landing on dried film can be blown off.
As of 2011, E6 kits are difficult to find and ship, but the following options at least are available:
Kodak used to make a 5L 6-bath kit similar to the Fuji X6 offering but it is discontinued. I therefore recommended that you buy the Fuji X6 kit for highest-quality processing, though it is harder to obtain outside Europe/UK.
If you're processing lots of film, it is possible to buy all of the components separately from Fuji or Kodak in large quantities (e.g. to make 20-100L). Bulk chemistry is by far the cheapest option per-roll but you're buying about $300-$500 of chemistry up-front and if you're not processing a lot of film then the components may go off before you exhaust them.
Bleach is the only very-expensive item; it has significantly more capacity per litre and it doesn't really go off, meaning that this is the component you want to purchase in bulk (with friends) if possible.
Professional E6 uses the 6-bath (dev, reverse, dev, pre-bleach, bleach, fix) process described above and if you can obtain a kit that follows that process, you should use that.
Simplified 3-bath kits designed for home-use combine several baths into a single stage, e.g. reversal and colour development become one bath and pre-bleach, bleach and fix become "blix".
The problem with the simplified approach is that the different baths (notably bleach and fixer) attack each other and have poor shelf-life once mixed. Though the first couple of rolls from the chemistry will look good, later rolls are likely to be of lower quality in a non-obvious way, e.g. tainted highlights, pale shadows and subtle colour shifts including crossover (different hue shifts in the shadows and highlights). Archival stability can also be affected due to insufficient bleaching and/or fixing.
See the Equipment section of C41 processing; all of the same comments and Jobo settings apply.
I have used only the Fuji 5L kit and can't speak from experience on any of the other chemistry options. I use a Jobo CPP-2 for E6 processing.
Back to Analogue Photography and Film FAQ