In 1941, Swiss engineer George de Mestral returned from a walk in the Alps and examined, under a microscope, the burdock burrs that kept sticking to his clothes and his dog's fur. What did he see that inspired Velcro's hook-and-loop design?
- The burrs were coated in a natural adhesive resin that stuck to any surface it touched, similar to tree sap
- The burrs were shaped like tiny suction cups that created a vacuum seal against the fabric's surface
- The burrs carried a faint static electrical charge that attracted them to the fibers of his clothing
- The burrs were covered in tiny hooks that caught on the small loops woven into the fabric of his clothing
Why D? And why not the others?
Correct answer: D. The burrs were covered in tiny hooks that caught on the small loops woven into the fabric of his clothing
Under the microscope, de Mestral saw that each burr was covered in tiny hooked spines that mechanically caught on the small loops naturally present in woven fabric and animal fur; he spent roughly a decade turning that purely mechanical fastening principle into a synthetic hook-and-loop fabric, eventually patented in the mid-1950s. The option describing a sticky adhesive resin is wrong because the burrs' grip is entirely mechanical, not chemical, and no adhesive substance is involved. The option describing tiny suction cups is wrong because suction requires a sealed, flexible cup shape pressing out air, which is not how a hook-and-loop bond works or looks under magnification. The option describing a static electrical charge is wrong because the attachment does not release when the charge would naturally dissipate, and it holds just as firmly on non-conductive materials, which static cling would not explain.
Source: Britannica-adjacent: National Inventors Hall of Fame, "George De Mestral and Velcro Fasteners"