Assertion: cellulose's use | /r/AtLocation | so-called safety film
Facets:
Source sentences:
text: The first commercial use of cellulose diacetate as a plastic was in so-called safety film, first proposed as a replacement for celluloid in photography soon after the beginning of the 20th century.
text: The first commercial use of cellulose diacetate as a plastic was in so-called safety film, which began to replace celluloid film in motion-picture photography in the 1920s.