Researchers have determined that the irritating screech produced when peeling Scotch tape results from shock waves generated by micro-cracks traveling at supersonic speeds. The findings, detailed in a new study, explain a phenomenon long observed but not fully understood. The research builds on decades of scientific interest in the tape's unusual properties.
Scotch tape, a household essential since its invention in 1930 by 3M engineer Richard Drew, continues to surprise scientists. Drew developed the transparent sticky tape for car manufacturing, using a cellophane roll coated with a sandpaper adhesive to avoid damaging paint during two-color designs. The tape gained popularity during the Great Depression for repairing items. Drew also co-invented the snail-style dispenser with colleague John Borden.
Physicists have long studied the tape's quirks. In 1939, scientists noted that peeling it produces light along the separation line, a form of triboluminescence first recorded in the 17th century. This effect occurs when materials are crushed, ripped, or scratched, generating light as electrons are displaced. Examples include diamonds glowing blue or red during cutting, ceramics emitting yellow-orange light from abrasive water jets, and sparks from crushing Wint-O-Green Life Savers in the dark. The candy's sugar crystals release electrons that collide with air's nitrogen atoms, producing UV light converted to blue by fluorescent methyl salicylate in the wintergreen flavoring.
In 1953, Russian scientists detected X-rays from peeling tape in a vacuum, a claim confirmed in 2008 by UCLA researchers who generated X-rays and a low-quality image of a finger. This only occurs in a perfect vacuum, posing no risk to everyday users.
The screeching sound, reminiscent of fingernails on a chalkboard, was previously linked to a slip-stick mechanism. A 2010 study by Sigurdur Thoroddsen of King Abdullah University in Saudi Arabia and colleagues used ultra-fast imaging to identify transverse cracks crossing the adhesive at supersonic speeds. A 2024 follow-up linked these cracks to the sound but lacked a mechanism.
The latest research, published in Physical Review E in 2026, tested whether the crack tips directly produce the sound pulses. Using synchronized high-speed video cameras and microphones, the team peeled tape with a metal rod. They found the screech arises from weak shock waves as cracks reach the tape's edge. “A partial vacuum is produced between the tape and the solid when the crack opens,” the authors explained. “The crack moves too fast for this void to be filled immediately, even though air is sucked in from the direction perpendicular to the crack. The void therefore moves with the crack until it reaches the end of the tape and collapses into the stationary air outside.” Each collapse generates a pulse, creating the characteristic screech.
DOI: 10.1103/PhysRevE.109.024401
