No carbon, but still potatoes...

...well, some kind of starch anyways. Thanks to my collaborator-in-all-things-color Zach Long at the Image Permanence Institute, I can now show you photomicrographs of the Alticolor film with an expiration date of July 1956 that I recently acquired. Given the date, this is from one of the last batches of the last form of the screen process originally introduced as the Autochrome in 1907. As I mentioned before, I have heard rumors that, at some point, carbon black was no longer used in the manufacture of the Lumiere additive screen processes, and that yeast grains replaced potato starch grains. Well, this Alticolor film does NOT use carbon black to fill the interstices between the grains (see upper image), but it DOES still use starch grains (as evidenced by the Maltese cross in each grain under cross polars-- see lower image). While it would be nice to have a more complete picture of how the various "Autochrome" products changed over time, this will have to do for today...

Dufaycolor

The last significant additive screen process to be introduced was a modification of the original Dufay dioptichrome process from before WWI. First released as a motion picture film in 1932, it was introduced for still photography in 1935 in roll, sheet, and film pack forms. A very fine screen structure, increased sensitivity, and simple reversal processing kept it in use into the 1950s for still photography.

Its use in motion pictures was short lived, though long enough to produce a number of feature-length films in the 1930s. Although not present on this sample from the Eastman House Film Technology Collection, a variable density soundtrack could be printed successfully into the image area.

Alticolor, the Autochrome of the 1950s

Thanks to a tip from Autochrome collector Mark Jacobs, I have just acquired my first roll of Alticolor film, actually an entire brick. Alticolor was introduced in 1952 by Lumiere, and was discontinued about 1955 (the expiration date on these rolls being July 1956). It was the final roll film version of the additive screen plate process originally introduced as glass plates in 1907 under the Autochrome name. In the early 1930s the first plastic support versions of the Autochrome were introduced under the names Lumicolor (cut sheet film) and Filmcolor (roll film). And finally the new and improved Filmcolor-Ultra-Rapid and Alticolor were introduced in the 1950s.
While all the Autochrome (and Filmcolor, etc...) that I've looked at with a microscope used potato starch grains and carbon black, there is a rumor going around that there was a change to yeast grains at some point, and that carbon black stopped being used to filled the interstices between the grains. So this very late-manufacture Alticolor film is a test of that rumor. I'll report back once I have examined this film with a compound light microscope.
I particularly like the cloth mailing bag that comes with every roll, addressed to the Lumiere processing center in Lyon. And the roll comes in a cute little aluminum capsule. And maybe the film can still be exposed and developed....but that's for another day.