Dufaycolor c1935-50
Dufaycolor was the most successful early colour photographic process. It was initially developed for cinè film but became popular as a medium format lantern slide process. Most commonly seen on 2.5in x 2.5in slides. The colour was made up of lines of orange green and blue. It was largely superseded by Kodakchrome from 1935.
Dufaycolor slides are always mounted between glass and edged with passepartout