No Compromises - Cs6 3-Bath Process vs. E6 6-Bath Processing

Posted by Brian Wright on

With the Cs6 "Creative Slide" process the number of processing baths for E-6 film is reduced from 6 to 3. The reversal step occurs during color development in a Color&Reversal bath, and the pre-bleach, bleach steps are combined with the fixing step in a Bleaches&Fixer bath. People often wonder, "What are the compromises with combined processing baths?", such as the Cr6 "Color&Reversal" 2-In-1 Slide Solution or the Bf6 "Bleaches&Fixer" 3-In-1 Slide Solution. The reality is that there are no compromises between fresh Cs6 and carefully replenished E-6 chemistry. 

Just see for yourself! We bracketed exposures of an extreme lighting situation just before sunset, with cool skylight and warm backlight. Snip tests were made and processed in each of our three 1st developers at 104ºf and the remaining 2 Cs6 baths at ~85-100ºf in a Patterson tank. The remaining film was sent to The Darkroom photo lab and processed with the 6-bath E-6 process. The Darkroom specializes in professional film developing and scanning. Their Sitte Tischer TruTrak dip & dunk processor maintains high professional standards with constant process control standards. All frames were scanned on the Skier Sunray Box with a Canon 5D mk2 with all the same settings and corrections.

Kodak Ektachrome E100 with an Olympus Zuiko 50mm at f/2 bracketed 1 stop over and under.

There is a lot of conjecture and skepticism out there regarding the stability and efficacy of "hobby" type chemistry kits, especially when it comes to slide processing. Some speculate that, "Professional labs must prefer the 6-bath E-6 process because it is superior." or posit, "Why then don't pro labs use combined processing baths like blix?" Well, that is not the whole story...

The 6-bath process appeals to professional labs because of the economics of chemical replenishment when processing large volumes of film. For instance, labs will add small concentrations of developing or clearing agents to the developer or fixer baths to replenish their activities as they exhaust from each roll processed. This can be repeated indefinitely if control strips are charted and pH is carefully controlled to maintain quality. The amount of replenishment depends on the amount of film developed, in what manner and how long the chemistry is stored, what contaminants have entered the system, and how far can the results deviate from ideal before they are deemed unacceptable. Additionally, when overexposed slides are processed the 1st developer, bleaches and fixer will be overworked and exhaust more rapidly. Conversely, underexposed slides will deplete the reversal and color developer solutions further. Chemical replenishment is a balance of improvisation and complicated science that saves labs money.

With the 3-bath process there is no need for replenishment because it is intended for small batches rather than large volumes. The Bleaches&Fixer solution cannot be replenished because oxidation increases bleach activity but decreases the ability of the fixing agents to clear the film. The Color&Reversal combined solution likewise could not be replenished accurately in a small batch. Although using a volume of chemicals more than once will not destroy its ability to process film, there are definite solution capacities and lifespans when reusing a batch of chemistry to process more rolls. 

1st Developers greatly determine the characteristics and quality of a slide, whereas the other 2 baths will process-to-completion and can be reused, multiple times before any loss of quality. The best results are actually obtained when 1st Developers are used only once. But if you must use a larger volume of chemistry to process a roll, there may be more solution capacity for further processing. Whenever a weakened 1st Developer is reused after processing only a few rolls, the development time can be increased instead of using chemical replenishment. Adding 4% to the time for each roll previously processed in 1 liter of recombined working solution can help compensate for exhaustion, up to the solution capacities. Reusing chemicals can cause color and density shifts. The more a chemical is reused the greater the shift. All developers start on an inexorable downhill exhaustion path the moment they are mixed, and exhaust faster in the presence of air, contaminants and high temperature, and suffer superimposed stepwise exhaustion with each use. This is why our 1st Developers are offered as 1000ml stock solutions, that are diluted further to a working solution, extending the volume capacity for single-use and achieving the best quality slides. 

Share this post

← Older Post Newer Post →

Leave a comment

Please note, comments must be approved before they are published.