FORMAT
PROJECT
THE VIDEOCASSETTE
COMPOSITION/CONSTRUCTION OF THE FORMAT
BACKCOAT
An electrically-conductive
carbon-black backcoat
designed to neutralize the
buildup of electrostatic charge
and to cling to the magnetic
tape within the cassette in a
manner that maintains tape-
roll uniformity, preventing
layer-to-layer slippage during
playback and handling.
BASEFILM
A durable polyethylene terephthalate (PET) or polyeythelene
napthalate (PEN) tape substrate which provides the physical
structure to the videocassette format.
BINDER
An adhesive material that binds the magnetic layer to the
basefilm and generates a smooth surface for the videotape
to run more effortlessly through the equipment. It is made
up of multiple chemical compounds.
MAGNETIC COATING
A thin coating of magnetic particles mixed with binders,
lubricants, head-cleaning agents, surfactants, and other
chemicals. Magnetic coating recipes are typically proprietary
and undisclosed, but generally contain an approximate ratio
of 40% magnetic particles to 60% other substances, including
lubricant, surfactant, and head cleaning agent.
A videocassette is comprised of a number of parts. This starts with a two-part outer casing shell made of polystyrene that is secured with two metal screws. Inside this shell, there are two spools of magnetic tape. These are positioned and mounted carefully, allowing them to rotate and be guided through the cartridge with minimal obstruction. All of the independent moving parts inside the casing are made from self-lubricating, anti-abrasive plastic material, such as polyacetal resin, and they are secured at special points on the inner shell through ultrasonic riveting or similar means. Despite the cartridge's complexity, the most at-risk part of a videocassette is actually the magnetic tape inside. This consists of four parts: a backcoat, a basefilm, a binder, and a magnetic coating.
© Chris J. Evans
© Chris J. Evans
© Chris J. Evans
© Chris J. Evans