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Film base: Difference between revisions
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'''Nitrate''' base is the infamously unstable and flammable stock that most release prints were made of until the early 1950s. Discontinued in 1951 and replaced with acetate "safety film". Look for the word "nitrate" written on the side of the film, though make sure it's not printed in from the original negative, as many nitrate prints were later re-struck on acetate or polyester stock. It's considered a hazardous material and becomes more dangerous as it deteriorates. Make sure you know the proper storage specifications for nitrate if you have any! | '''Nitrate''' base is the infamously unstable and flammable stock that most release prints were made of until the early 1950s. Discontinued in 1951 and replaced with acetate "safety film". Look for the word "nitrate" written on the side of the film, though make sure it's not printed in from the original negative, as many nitrate prints were later re-struck on acetate or polyester stock. It's considered a hazardous material and becomes more dangerous as it deteriorates. Make sure you know the proper storage specifications for nitrate if you have any! | ||
==How to tell the difference== | ==How to tell the difference (poly and acetate)== | ||
* [https://www.nps.gov/museum/coldstorage/pdf/2.3.1b.pdf A guide] for making a film viewer for easy identification of acetate or polyester film base. Older polarized 3D glasses (they use spherical polarization) work great for this if you can find some. Real-D glasses do NOT work. Polyester base will create a sort of "rainbow" effect when viewed between the cross polarized lenses, acetate base will not. | * [https://www.nps.gov/museum/coldstorage/pdf/2.3.1b.pdf A guide] for making a film viewer for easy identification of acetate or polyester film base. Older polarized 3D glasses (they use spherical polarization) work great for this if you can find some. Real-D glasses do NOT work. Polyester base will create a sort of "rainbow" effect when viewed between the cross polarized lenses, acetate base will not. | ||
*You can also differentiate between the two by holding up the reel of film to a strong light. With polyester base prints the light will shine through, with acetate it will appear opaque. I find this is true most of the time, though the polarized lens test is more definitive. | *You can also differentiate between the two by holding up the reel of film to a strong light. With polyester base prints the light will shine through, with acetate it will appear opaque. I find this is true most of the time, though the polarized lens test is more definitive. | ||
*Polyester is very difficult to tear with your hands, it stretches rather than snaps. However this test is not recommended as it requires you to damage the film. However an accidental film break or a | *Polyester is very difficult to tear with your hands, it stretches rather than snaps. However this test is not recommended as it requires you to damage the film. However an accidental film break, or a tearing of the [[leader]] (if there is any) may give you an answer. Just make sure the leader is original to the print, as sometimes a leader or countdown may be spliced onto a print of a different base. | ||
*A poly print may have "Estar" written along the edge of the print, acetate may have "safety". Although some new prints struck from acetate negatives may still have "safety" written on them. So it's helpful thing to check for, but use it along with other identifying qualities. | |||
==Resources== | ==Resources== | ||