Introduction -Tape Construction

Apart from very early homogeneous types, most tapes consist of three primary components:

  • the base
  • magnetic particles or pigment
  • binder.

The earliest commercial formulations used cellulose acetate as a support or base film as well as a binder for coated and homogeneous tapes. Poly(vinyl-chloride) or PVC has also been used since 1940 1, but both have been superseded in modern tapes by poly(ethylene-terephthalate) or PET, which has superior physical, hygroscopic and thermal properties. Under commonly encountered conditions of storage and use, it is one of the most chemically stable polymers available 2. Problems with physical deformation can occur through mis-handling or improper collection management, but with care these are normally of secondary concern.

Most modern tapes incorporate a back-coating of carbon particles to reduce static electricity which can discharge and attract dust. Pigmentation was first introduced in the late 1940s to distinguish the reverse side of the tape from the playing surface. From the 1950s as tape surfaces became smoother, matt back-coating was introduced to reduce air entrapment and to avoid slippage between layers or displacement of loose turns (ribbing or leafing) during spooling and in subsequent handling and storage.