==Diacetate motion picture film stock== 

 Where does the author get 1957 as the year of cessation of production from?  EK introduced triacetate film base in 1948, which rapidly superseded all other bases in the market (principally nitrocellulose for professional motion picture use and diacetate for amateur motion picture and still photographic film).  I suppose it's possible that a Soviet bloc (e.g. Tasma) or Asian manufacturer kept making diacetate well into the 1950s, but I haven't come across any diacetate film made as late as 1957.