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Core
A core is a chemically-inert plastic cylinder used in film manufacturing, development, and storage. Cores are available in all standard film gauges: 35mm, 16mm, 70mm, and even Super 8. They are available in several sizes: 4", 3", 2", and 1" for trailers
Usage
Raw film stock is supplied to laboratories on a plastic core. After a new print is manufactured, it is also wound onto a plastic core and shipped to the producer in this form. The film must be transferred to a projection reel before it can screened.
Most distributors send films to theaters on shipping reels, though films are sometimes shipped to theaters on cores. A well-stocked booth must be able to accommodate film whether it arrives on a reel or a core. The projectionist must use a split reel or film transfer flange to safely transfer film from a core to a projection reel. Film should never be projected from a split reel.
Archives typically store all films on cores, whether they are projection prints or pre-print elements. There are several advantages to storing films in this manner: cores allow for more compact storage and substantially limit the potential for external contamination (e.g., rusty reels). Archives will also occasionally ship prints to exhibitors on cores.
Proper Handling and Potential Pitfalls
Film on a core must always be handled more carefully than film mounted on a reel. If the film is not wound tightly enough around its core, it can slip off and create a film spill. To limit the potential for a film spill, projectionists and archivists should always use both hands to brace the film when transferring it to and from its can.
These concerns can be exacerbated when holding the core horizontally, with the risk of loosely packed film spilling out by the force of gravity. It is often easier to transfer cored film by holding it vertically, firmly gripping the film between the outer layer of the core (leaving the center open to receive the split reel hub) and the outer edge of the film with one hand, while holding the split reel flange or film can with the other. This also makes it easier to align the drive pin of the split reel with a gap in the core.