Here’s why Scotch tape screeches when it’s peeled

For nearly a century, Scotch tape has been a staple in households, yet it continues to unveil fascinating scientific secrets. Recent research has shed light on the high-pitched screech produced when the tape is swiftly peeled off—an annoying sound reminiscent of nails on a chalkboard. This noise arises from shock waves generated by micro-cracks that travel along the tape at supersonic speeds, as detailed in a new study published in the journal Physical Review E. The invention of this transparent adhesive can be credited to 3M engineer Richard Drew, who first developed it in 1930. The need for a reliable tape arose from the challenges faced in car manufacturing, particularly with two-color designs. The adhesives used at the time were so strong that they often peeled off paint along with the tape, necessitating manual touch-ups. Drew innovated by creating a sandpaper adhesive with the perfect level of stickiness, which he applied to a roll of cellophane. Interestingly, Drew also co-invented the iconic snail-style tape dispenser alongside his colleague John Borden. Scotch tape became exceptionally popular during the Great Depression, as people turned to it for repairing items instead of purchasing new ones. This enduring popularity has continued into the present day, making it a favored choice for many. The tape has also intrigued physicists for decades. In 1939, scientists discovered that peeling tape could emit light, creating a glowing line where the end of the tape detaches from the roll. This phenomenon, known as triboluminescence, refers to the light generated when materials are crushed, torn, or rubbed together. For instance, diamonds can emit a blue or red glow during the cutting process, and ceramics often shine with a yellow-orange hue when cut by abrasive water jets. A well-known example of triboluminescence can be observed with Wint-O-Green Life Savers. When crushed in a dark environment, they produce visible sparks due to the sugar crystals. This effect occurs when the crushing action causes electrons to be stripped from the molecules, allowing them to leap across a gap to the more positively charged side. The colliding electrons interact with nitrogen atoms in the air, which temporarily absorb the energy and release it as UV light. The wintergreen oil in the candy enhances this effect by absorbing UV light and converting it into a visible blue glow.