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E-6 Slides Processing

As Kodachromes have disappeared, all actual color reversal films use E-6 process.

This process being standardized, all films whatever their make, type or speed can be developed together.

Summary

• Process
      6 baths
      3 baths

• Equipment
      Equipment setup
          Temperature
          Agitation

• Chemicals
      Mixing
      Shelf-life
      Processing times

Process

6 baths

E-6 slides processing requires the following steps:

1. first developer: similar to a B/W developer, it produces a negative image made of metallic silver.
2. washing: stops the action of first developer
3. inversion: reverts the image. Often done in the past by exposure to light, it is actually more commonly done by a chemical step.
4. color developer: it produces the colors of the slide. The film contains color couplers added during its manufacturing and the color developer reacts with the couplers to produce the color dyes proportionally to the image density.
5. pre bleach: stabilizes the dyes for the rest of the process.
6. bleach: converts the metallic silver image in compounds that can be fixed.
7. fixing: removes all the silver contained in the emulsion, only the dyes remain.
8. washing: removes fixer and other compounds from the film.
9. stabilizer or final rinse: stabilizes the dyes, usually has a biocide action and also contains a wetting agent to facilitate drying.

3 baths

Depending on the chemicals, several steps can be combined. A classic 3-baths process can be:

1. first developer: similar to a B/W developer, it produces a negative image made of metallic silver.
2. washing: stops the action of first developer
3. color developer: it produces the colors of the slide. The film contains color couplers added during its manufacturing and the color developer reacts with the couplers to produce the color dyes proportionally to the image density.
4. washing: avoids contamination of bleach-fix
5. bleach-fix (or blix): converts the metallic silver image in compounds (bleach) that can be fixed (fixer), only the dyes remain.
6. washing: removes fixer and other remaining compounds from the film.
7. stabilizer or final rinse: stabilizes the dyes, has a biocide action and contains a wetting agent to facilitate drying.

Equipment

To obtain a maximal quality and consistency, we must respect a few points:

• constant and precise temperature
• regular agitation
• consistent process times
• fresh chemicals

Even if it is possible to build a simple water bath and process by inversion like for B/W films, I do recommend the use of a small processor.
Amongst the amateur models, the most common are made by Jobo, notably the CPE-2, CPA-2 and CPP-2 series.
They assure precision and consistency of temperature and agitation.
Up to the operator to ensure consistent process times (a stop-watch is enough) and chemicals freshness.
This last point being the major cause of failures, please, throw away old chemicals: they will not make you save money.

You also need:

• drums adapted to the processor, size and number of films you want to develop.

• a thermometer with a *true* 1/10th °C precision. Many electronic models have only a display precision of this sort but absolutely not a real precision, avoid them !
  You can find some electronic precision models (Greisinger.de, etc ...) but their cost is still pretty high.
  I'm lucky to still have an old lab mercury model but these are pretty difficult to find nowadays.
  And mercury not being very environment-friendly, I strongly suggest an electronic precision model instead.
  The best quality/price ratio is the common medical thermometer measuring fortunately the same temperature range we us in the E-6 process. As it also maintains the temperature reading while cooling down, it is also very agreeable in this use.

• graduates adapted to the quantities to measure: avoid graduates to large.
  You need then several models, by example: 50, 150, 500 and 1000ml.
  And also some pipettes to adjust minute quantities.

Equipment Setup

Here is an example with a Jobo CPA-2 processor, completely valid for its brothers CPE and CPP.

Temperature

All process is normally operated at 38°C but the most critical step is the first developer, after that, come the first wash, reversal and color developer which are also important. All other steps are less critical.

You must ensure the temperature inside the drum is really what is recommended.

To do so, increase gradually processor temperature until it reaches 38°C inside the drum.
Due to water's high thermal inertia, you'll have to wait enough it stabilizes.
Once you've reached the right and stable temperature inside the drum, you can measure the temperature on various points of the processor. Select the most convenient as reference.
In successive batches, once temperature reaches this value at the reference point, you'll be sure the temperature inside the drum will be fine.

This setup has to be done only once, so, don't be afraid to lose a complete afternoon to do it carefully.

Agitation

Rotation speed is 75 rpm (position "P").

Chemicals

The number of kits for the amateur (up to 5 liters) available has shrinked a lot these last years but there are still a few manufacturers that still propose 3 and 6 baths kits.

3 or 6 baths ?
Although I prefer the 6 baths, the few 3-baths that I tested perform pretty well.
Although 3-baths kits are not cheaper, their strong point is in simplifying the process.
Note: the stabilizing bath is often not counted (although included in the kit) in the number of baths, so a 6-bath kit contains 7 chemicals !

More than the number of baths, processing one-shot is very important to have consistent chemicals and, thus, results.

I used for long the Kodak 6-baths kit in 5 liters (ref. 525 6763 in Europe) that allowed to process roughly 40 films 135-36.
The original documentation on this kit:
Kodak, E6 Single-Use Chemistry Kit - General Information - (local copy)
Kodak, E6 Single-Use Chemistry Kit - Technical Information - (local copy)

Among the chemistries available at the time being in Europe:

• Fuji Hunt 3E6 (3 baths/5 liters) ref. 958967
• Fuji Hunt Chrome 6X (6 baths/5 liters) ref. 979641
• Tetenal Colortec E6 (3 baths/1 liter) ref. 102031
• Tetenal Colortec E6 (3 baths/5 liters) ref. 102034

Fuji chemicals (3E6 and Chrome 6X) perform as good as the former Kodak kit. I did not test the Tetenal ones.
Fuji documentation:

• Documentations List
• References' List - Kits Replacement (2009)
• 3E6: Packaging (local copy) - Instructions (local copy)
• Chrome 6X: Packaging (local copy) - Instructions (local copy)

There are various manufacturers in North America but sending these chemicals is problematic (corrosive liquids are prohibited in planes) and rather pricey (close to the cost of the kit).

Mixing

Most if not all of them are liquids and you can dilute only what you need for the number of films of the batch being processed.
Please note that the smaller the quantities to dilute, the more difficult they are to measure precisely and, thus, error margin will increase.
You have to be particularly meticulous and use graduates and pipettes adapted to these little quantities.

I only dilute the required quantity, concentrates remaining in their original package.
Here are the quantities for various drums combinations with Jobo 1500 serie, rotary processing, and my CPA-2:

Minimum chemical quantities per drum size

These are the minimum quantities to physically cover the films when processing by rotation.

Minimal quantity of chemicals per film

Whatever the processing method, from a chemical perspective, there is a minimal quantity of chemicals required to fully process a film.
5-liters kits from Kodak, Fuji and Tetenal can process roughly 50 rolls, that 10 rolls 135-36 per liter or 100ml per roll.

Quantity of concentrates to obtain the various final volumes

We can see that for a one-shot processing with the minimum quantities required by rotation we reach 40 rolls, that is pretty close to the maximum processing capabilities of the kits and that with all advantages of the one-shot processing.
The following tables show the concentrates quantities, in milliliters, required for each size in the Jobo line 15xx.

Fuji 3E6 kit:

Kit Fuji Chrome 6X:

The former Kodak kit:

Comments:

To prevent any water problems, I use demineralized water for:
- 1st Developer
- Reversal Bath
- Color Developer

Demineralized water could be used for the first wash too. To maintain the wash water to the right temperature, two 1-litre plastic bottles are placed in the basin right to the tank.

Developers are very sensitive to contamination especially by bleach or fixer, ware should be cleaned very thoroughly between each mixing or use separate utensils for developers and the other chemicals.

The final rinse is hard to clean completely and can influence the next development. So, use another tank for the final rinse and don't immerse the reel, just open it and let fall the film in the product. Agitation should be light to avoid foaming.

Shelf-life

First developer is the most sensible to aging. Concentrate shelf-life can be increased by reducing contact to air.

Here are a couple of methods:

• Introducing a heavy and non-reacting gas into the bottles.
  This gas forms a layer over the concentrate and separates it from air.
  You can find such gazes available commercially like Tetenal Protectan. But since I saw its ingredients, a mix of butane and propane, I replaced it by lighter gas, commonly available in Switzerland as used in heaters for our national meal, la Fondue ...
  Open Kodak kit shelf-life is then around 10 months.

• Concentrate is put into brown glass bottles, the kind you find in pharmacies, and kept in the dark.
  I've chosen 200ml bottles as this quantity makes one liter of final solution which lets me develop 8 rolls 135-36 in a single batch.
  Each bottle is filled with exactly 200ml of concentrate and some demineralized/distilled water is added to fill the bottle completely up to the cap.
  Once needed, the bottle is diluted to the final liter.
  I can't give you yet a precise shelf-life as I've used this method to E-6 kits only recently but as I use it since a long time with B/W developers with great success (Xtol test has gone beyond 4 years of shelf-life), I'm pretty confident it will give better results than the gas method.

Processing Times

First developer time is very important, all others are used to completion, in doubt, you've better to increase the time than decrease it.

Fuji 3E6:

Push/pull Process:

Fuji Chrome 6X:

The former Kodak kit:

Push/pull Process:

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