10. Magnetic tape

In the early phase of its technology, magnetic tape could be universally described as brown with one side shiny and the other dull. This description is today the exception rather than the rule. Tape coatings now come in varying shades from light brown to black. Tape backings range from black to brown to red or pink and even yellow, green and blue. Tape textures may be shiny, silk or matt. Tape thicknesses are identified as standard play, long play, double play and even triple and quadruple play. Perhaps most confusing of all are the manufacturers descriptions of their tapes as being low noise, low print, high output, extended frequency range and so on. Finally, cassette products come in another host of forms; ferrous, super-ferrous, chromium dioxide, ferrous-chrome and cobalt - all claiming various advantages.

The tape scene can indeed be confusing, even to the initiated. What then can the oral historian make of it? What is 'good' tape?

Quite a long list can be drawn up of the characteristics which would be desirable for the ideal all-purpose magnetic tape. It should combine good physical strength and flexibility; it needs a chemically inert base, yet one which binds well to the oxide coating; the coating itself should give good sensitivity, exclude distortion, preclude magnetic noise and have a low print-through characteristic; the oxide layer should have a high Signal handling capability without reducing the tape's upper frequency capacity and the texture of the tape should facilitate smooth and even winding.

Unfortunately such a model tape does not exist. Many of the desirable qualities mentioned above are conflicting ones and by incorporating some of these characteristics into their products tape manufacturers unavoidably exclude some others which are mutually incompatible. As a result all tapes are something of a compromise, being geared more to one application than another. The best choice of tape is in large measure influenced by the particular use in mind and, ideally, different types should be selected for different machines and purpose.

The tape characteristics and certain brands which can be recommended are set out below under the three main activities which collecting centres are generally engaged in.