I recently did spring cleaning and found in the back of my freezer a 100' roll of 5241 (Ektachrome EF) E-4 process film (expiration 1973). I mixed a liter of chemistry using formulae from Pat Dignan's old photochemistry formulary. I shot tried a series of bracketed MacBeth chart images, all of which came out quite bad--useless, in fact.
The E-4 emulsions are not hardened as are modern films. They are quite soft and require a pre-hardener and processing at 85F. Even so, I got reticulation in this old soft emulsion. Just for fun I tried a strip at 75F and the result was better but still with poor color and a very high fog level. Doing these experiments makes one appreciate how really good E-6 films have become. One other item of note for E-4 is the great difficulty to bleach this film. I tried some E-6 bleach and found it to work but at triple the expected bleaching time. The E-4 bleach formula is a ferricyanide-based bleach as is used for black & white bleaching, but is is more concentrated owing to the difficulty to bleach this film. Once bleached however, it's a snap to fix.
I usually squeege excess stabilizer from my 35 mm E-6 films. Do that to an E-4 film and you will find parts of the soft emulsion peeling off onto your photo sponge, especially around the sprocket holes where the cut edges are exposed.
Overall I wasted a couple of days fooling with this film that is obsolete, and for good reason! As I said, I appreciate the quality of modern E-6 emulsions that are available! Working with E-4 reminded me how primitive color photography used to be, and also why Kodachrome has stood the test of time and continues to be the standard for quality.