Scotch tape has been sticking to desks and wrapping paper for nearly a century, yet it has continued to puzzle physicists. A new study has finally explained why rapidly peeling the tape produces that piercing screech often compared to fingernails on a chalkboard. The culprit is not just friction, but tiny shock waves created by microscopic cracks racing along the tape at supersonic speeds.
The findings were detailed in a recent paper published in Physical Review E, where researchers used high-speed imaging and synchronized microphones to pinpoint the exact source of the sound, according to Ars Technica. By manually peeling tape with a metal rod and filming the process with ultra-fast cameras, the team captured both the fractures forming in the adhesive and the pressure pulses moving through the air.
Scotch tape itself dates back to 1930, when 3M engineer Richard Drew developed the first transparent adhesive tape to help auto manufacturers with two-tone paint jobs. The product became wildly popular during the Great Depression, when households used it to repair items instead of replacing them. Over time, physicists discovered the tape had more unusual properties. Peeling it in the dark can produce light, a phenomenon known as triboluminescence. In a vacuum, it can even generate X-rays, as demonstrated in 2008 by UCLA researchers.
Sound, however, remained less understood. Scientists had long suspected the classic slip-stick mechanism, where adhesive alternates between sticking and releasing, played a role. In 2010, researchers identified transverse micro-cracks traveling across the tape’s adhesive at supersonic speeds. A later study in 2024 linked those cracks directly to the screeching noise but stopped short of explaining how the sound waves formed.
The latest research fills that gap. The team found that as each micro-crack propagates, it creates a partial vacuum between the tape and the surface beneath it. Because the crack tip moves faster than air can rush in to fill the gap, the void travels with the crack until it reaches the tape’s edge. When that void collapses into surrounding air, it generates a sharp pressure pulse.
Each fracture tip produces one such pulse, and the rapid succession of these tiny shock waves creates the characteristic screech. In short, every peel is a cascade of microscopic sonic booms happening right at your fingertips.
The study has been published here.