You’ve got a legitimate reason to flinch when you’re peeling off a roll of Scotch tape. That annoying screech is actually tiny cracks traveling at supersonic speeds.

An international team of physicists used high-speed cameras and sensitive microphones to capture ordinary Scotch tape as it peels away from its roll, identifying a train of shock waves responsible for that screeching sound. The results are detailed in a study published in Physical Review.

The curious case of Scotch tape

Although seemingly basic, Scotch tape has been on physicists’ minds for a long time. Minnesota engineer Richard G. Drew invented the transparent waterproof tape in 1930 using a blend of oils, rubber, and resins on a cellophane backing.

In 1939, scientists discovered that peeling Scotch tape in the dark produces a visible blue glow due to a build-up of electrical charge and the sudden tearing of the adhesive. The phenomenon, known as triboluminescence, is the same reason diamonds glow when they are cut.

Later in 1953, a team of Russian scientists reported that peeling Scotch tape in a vacuum was energetic enough to produce X-rays. As the adhesive peels off, the separation of opposite electrical charges causes electrons to jump from the sticky tape to its backing at high speed.

Then there was the sound that Scotch tape makes when it peels off its roll. Scientists began trying to unravel the mystery of the screeching sound over a decade ago.

In 2010, recent study co-author Sigurdur Thoroddsen of King Abdullah University in Saudi Arabia used ultra-fast imaging to capture a sequence of transverse cracks traveling up the detached part of the tape at supersonic speeds. A follow-up study in 2024 confirmed that the screeching sound was directly linked to the transverse cracks, although the mechanism behind it remained unknown.

Roll the tape

For the new study, the team of scientists recorded the fractures using two ultra-high-speed cameras while simultaneously capturing the sound with two synchronized microphones.

The results finally filled in the gap of previous studies. As the adhesive peels off, it doesn’t do so evenly but rather tears in narrow bands that travel sideways across the tape. These transverse fractures travel at speeds between 560 and 1,340 miles per hour (250 to 600 meters per second), almost twice the speed of sound.

The fractures leave behind a partial vacuum between the tape and its solid backing, but because they travel so quickly, there isn’t enough time for air to fill the void immediately. The void then moves with the fractures until it reaches the end of the tape and collapses into the stationary air outside, according to the study. When the fracture tip reaches the edge of the tape, the collapsing void fires off a sound pulse. And that’s when we hear that notorious screech.

Keep this in mind the next time a strip of tape makes you wince—you’re not just hearing adhesives at work, but microscopic sonic booms screeching across an ordinary roll of tape.