Editing 35 mm movie film (section)

===Safety film===
{{Main|Safety film}}
Although [[Eastman Kodak]] had first introduced [[acetate]]-based film, it was far too brittle and prone to shrinkage, so the dangerously flammable nitrate-based cellulose films were generally used for motion picture camera and print films. In 1949 Kodak began replacing all nitrocellulose (nitrate-based) films with the safer, more robust [[cellulose triacetate]]-based "Safety" films. In 1950 the [[Academy of Motion Picture Arts and Sciences]] awarded Kodak with a Scientific and Technical [[Academy Award]] ([[Academy Awards|Oscar]]) for the safer triacetate stock.<ref>{{cite web|url=http://www.kodak.com/global/en/corp/historyOfKodak/impacting.jhtml?pq-path=2217/2687/2691 |title=Broadening the Impact of Pictures |work=Kodak.com |access-date=August 29, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20120201104103/http://www.kodak.com/global/en/corp/historyOfKodak/impacting.jhtml?pq-path=2217%2F2687%2F2691 |archive-date=February 1, 2012 }}</ref> By 1952, all camera and projector films were triacetate-based.<ref name="tafi">{{cite book|last=Slide|first=Anthony|url=https://books.google.com/books?id=DO8JAQAAMAAJ|title=The American film industry: a historical dictionary|publisher=Amadeus Press|year=1990|isbn=978-0-87910-139-8}}</ref> Most if not all film prints today are made from synthetic [[polyester]] safety base (which started replacing Triacetate film for prints in the early 1990s). The downside of [[polyester]] film is that it is extremely strong, and, in case of a fault, will stretch and not break–potentially causing damage to the projector and ruining a fairly large stretch of film: 2–3&nbsp;ft or approximately 2&nbsp;seconds. Also, polyester film will melt if exposed to the projector lamp for too long. [[Original camera negative]] is still made on a triacetate base, and some intermediate films (certainly including internegatives or "dupe" negatives, but not necessarily including interpositives or "master" positives) are also made on a triacetate base as such films must be spliced during the "negative assembly" process, and the extant negative assembly process is solvent-based. Polyester films are not compatible with solvent-based assembly processes.