A core is a chemically-inert plastic cylinder used in film manufacturing, development, and storage. Cores are available in all standard gauges: 35mm, 16mm, 70mm, and even Super 8. They are available in several sizes: 4", 3", 2", and 1" for trailers
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 in exceptional circumstances. 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 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 seated on a reel. If the film is not wound tightly enough around its core, it can unspool 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.