Stuck in the Past: Stick Shed Syndrome

As discussed in our last blog post on tape mold, the vessel that keeps memories ageless is not itself exempt from the ravages of time. Depending on when your magnetic tape was manufactured, you might find yourself in a sticky situation.

A tape that has shed its binder

Aging magnetic tape made with particular binding agents can develop “sticky shed syndrome”, which can shred your tape when played! Symptoms of this decay can be observed in slowed performance from the tape, shedding residue onto the playback heads, or worst of all, the squealing sound of your tape shredding.

To experience sticky shed syndrome, just add water. Really, it is caused by the binding agents used for magnetic tape absorbing water, notably tapes made by Ampex in mid seventies to late eighties and 3-M from 1980 to ‘88 (wendycarlos.com). We also have started seeing sticky shed syndrome pop up in 3/4 inch U-Matic tapes and even some early VHS tapes. Unfortunately, the binding agent experiences degradation through hydrolysis. Hydrolysis is a chemical reaction in which molecules split by reacting with water. For example, with the use of an enzyme (often an acid) to speed up the reaction, hydrolysis is how your body tends to break down food (britannica.com).

Fortunately, the components of these tapes have a higher melting point than the evaporation point of water. Meaning, applying heat will remove the water without destroying the tapes. As such, we can pop your tape right into a food dehydrator, easy peasy. Okay, it’s not that simple. Even if your tape won’t melt at certain temperatures, the materials may expand. In building skyscrapers, expansion joints are used to accommodate the thermal expansion and shrinkage of steel. Likewise, at Archival Works, we account for the risk of expansion for baking tapes and add bracing to maintain structural integrity.

Once this water is removed, the materials are settled into place and the tape can be played without annihilation. Battle won—for now. Within a month, the tape can become sticky again. It is thus advisable to get sticky shed tapes digitized in order to be safely preserved. I do not recommend having chronically baked tapes. The war against time can be won, at least in the case of magnetic tapes.