Why do old tapes squeal?
Audio and video tapes suffer from the dreaded loss of plasticiser problem or something akin to it and in consequence lose their suppleness and flexibility, causing poor contact with the record/playback head as well as a binding action and squealing noise. An alternative explanation names hydrolisation is named as the culprit, stating that the binder compound used to stick the magnetic particles to the plastic backing – has absorbed water from the air (possibly replacing the lost plasticiser). The water molecules actually make the tape expand a bit, so it doesn’t fit the machined tape-guides properly anymore; and they can interfere with the lubrication impregnated into the tape; and it is theorised they can even interfere with the polished smoothness of the tape surface. Why this should affect some tapes and not others depends on the formulation of the plastic backing and binder. Tapes of the 1950s and 60s are unaffected but these were made using whale oil (it is asserted) and the probl
