2.2.1.1.2 The so-called Sticky Tape or Sticky Shed Syndrome (SSS)
From the mid-1970s onward, sticky tapes and pigment shedding have been frequently observed. These tapes often squeal during replay due to friction because of sticky pigment and binder particles deposited on tape guides and audio and video heads. This clogs the heads and leads to a significant loss of high frequencies (audio), or a complete breakdown of the signal (video).
Hydrolysis of pigment binders has been the most frequent explanation for these problems. Because this kind of hydrolysis is reversible to some degree, such tapes generally can be reconditioned for replay by exposing them to low humidity and elevated temperatures (or a combination thereof: for details see IASA-TC04, 5.4.3.4).
Recent research11, however, reveals that there are several additional possible reasons for the stickiness of tapes: primer exudation, surplus of dispersion agents, lubricant exudation, and, finally, uneven dispersion of hardener. Except for the latter, which is incurable, treatment similar to that of binder hydrolysis can be used: elevated temperature12 coupled with mechanical cleaning. This will help make tapes reproducible during a time window that is long enough to permit the transfer of their contents.
11. Schüller 2014.
12. Temperatures employed in such processes have varied between 60°C (for audio only) and 40°C. As elevated temperatures may mechanically distort tapes, which is specifically critical for video tapes, and may also have a negative influence on the further life of the tape, present thinking suggests to use the lowest possible temperature which is still effective.
