The VHS (Video Home System) cassette is not merely a vessel for analog signal; it is a layered composite of synthetic ambitions. Its anatomy consists of a 0.5-inch (12.7 mm) strip of polyester (polyethylene terephthalate) base film, coated in a magnetic pigment—typically gamma-ferric oxide ($\text{Fe}_2\text{O}_3$)—and bound to that base by a polyurethane dispersion.
In the naturalist's eye, the failure of the VHS tape is not a sudden erasure, but a slow, chemical surrender. The most singular pathology is "sticky-shed syndrome," a phenomenon of binder hydrolysis. The polyurethane binder, intended to be a permanent adhesive, proves to be hygroscopic. Over decades, it absorbs water molecules from the ambient air, which infiltrate the long hydrocarbon molecular chains of the polymer. The binder breaks down, reverting from a stable solid to a gummy, adhesive residue.
The result is a somatic crisis: as the tape passes across the head drum at 1,798.2 RPM (in NTSC machines), the degraded binder "sheds" the oxide layer. The memory literally peels away from its support, leaving a trail of magnetic dross upon the guides, rollers, and capstans. The image on the screen does not merely fade; it stutters and tears as the physical medium adheres to the machine that is attempting to read it.
There is a desperate, almost surgical intervention used by archivists to combat this: "baking." By subjecting the tape to a controlled, low-temperature heat, the absorbed water is driven out of the binder, temporarily re-stabilizing the polymer. It is a fragile resuscitation. The baking does not cure the hydrolysis; it merely pauses the decay, granting the tape a brief window of playback before the moisture returns and the glue fails once more.
If the CD-ROM's rot is a blinding of the observer, the VHS tape's decay is a dissolution of the self. The memory becomes a liquid, a sticky residue that clings to the mechanism of its own retrieval. We are left with a medium that, in its attempt to persist, becomes an adhesive, binding itself to the very iron that seeks to liberate its ghosts.
Sources: