Scientists crack the case of “screeching” Scotch tape

In 1953, Russian scientists peeling off tape in a vacuum reported detecting electrons with enough energy to emit X-rays. Other scientists were skeptical, but the phenomenon was finally confirmed in 2008, when UCLA physicists produced X-rays by unrolling a roll of tape in a vacuum chamber. The goal was to harness triboluminescence for X-ray imaging, and the team produced a low-quality X-ray image of a lab member’s finger (see image below). Fortunately, this only works in a perfect vacuum, ensuring the safety of everyday scotch users.

A shock to the system

Scotch tape produces sound and light, usually attributed to the slip-stick mechanism at play during the peeling process. In 2010, co-author Sigurdur Thoroddsen of King Abdullah University in Saudi Arabia and colleagues used ultrafast imaging to identify a crucial microfracture phenomenon of the sliding mechanism: a sequence of transverse cracks that propagate across the width of the adhesive at supersonic speeds. A follow-up study in 2024 found a direct correspondence between the screeching noise and these transverse cracks, but did not identify a mechanism.

This is the subject of this latest study. Thoroddsen et al. wondered whether the sound was directly generated by the rapidly moving tip of a crack, which would also produce the distinctive discrete sound wave pulses associated with the peeling of Scotch tape. The authors experimentally tested their hypothesis by simultaneously performing high-speed imaging of propagating fractures and sound waves propagating through air. They manually peeled off the tape using a metal rod, capturing the cracks with two video cameras and the sound with two microphones synchronized to the video camera, to better locate the origin of the pressure pulses.

Their results showed that the screeching comes from a series of weak shocks that peak when the transverse cracks reach the edge of the ribbon. The supersonic speed at which they travel, relative to the surrounding air, is crucial for the generation of these shock waves. “A partial vacuum occurs between the ribbon and the solid when the crack opens,” the authors explain. “The crack is moving too fast for this void to be filled immediately, even if air is drawn in from the direction perpendicular to the crack. So the void moves with the crack until it reaches the end of the ribbon and collapses into the stationary air outside.” Each time a fracture tip reaches the edge of the band, it generates a pulse of sound, hence the telltale scream.

DOI: Physical Review E, 2026. 10.1103/p19h-9ysx (About DOIs).