Zipper

The zipper solved a problem that buttons had dominated for centuries: how to join two pieces of fabric quickly, securely, and reversibly. Its emergence required precision metalworking fine enough to stamp identical interlocking teeth by the thousands—a capability that existed by the 1890s but hadn't yet been applied to clothing fasteners.

Bird feathers had solved an analogous problem hundreds of millions of years earlier. Each feather consists of a shaft with barbs branching off, and each barb carries tiny barbules with hooks that interlock with adjacent barbules. When a bird preens, it's essentially re-zipping its feathers—running a slider (its beak) along the separated elements to restore the interlocked surface. The mechanism is so effective that feathers can be waterproof, aerodynamic, and insulating all at once.

Whitcomb Judson, a Chicago engineer, filed his first patent for a "clasp locker" in 1891. His device used hooks and eyes operated by a sliding guide—conceptually correct but practically unreliable. The hooks would pop open under strain; Victorian ladies complained bitterly. Judson debuted his invention at the 1893 Chicago World's Fair, but commercial success eluded him.

The breakthrough came from a Swedish-American engineer, Gideon Sundback, who joined Judson's company in 1906. After his wife died in 1911, Sundback buried himself in work. He redesigned the fastener from first principles: instead of hooks and eyes, he created rows of identical cup-shaped teeth that nested into each other. He increased the density from four teeth per inch to ten or eleven. He engineered a Y-shaped slider channel that bent the fabric tape precisely enough to engage and disengage teeth one by one. His "Hookless Fastener No. 1" was patented on April 29, 1913—now celebrated as National Zipper Day.

The device still lacked its name. B.F. Goodrich adopted Sundback's fastener for rubber boots in 1923, calling them "Zippers" because they could be fastened with a single zip of the hand. The name stuck to the mechanism itself.

Mass adoption was slow. For decades, zippers appeared mainly on boots and tobacco pouches. The fashion industry resisted: buttons were traditional, zippers seemed mechanical and cold. The turning point came in 1937 when French designers praised zippers in men's trousers. The press dubbed it the "Battle of the Fly," and the zipper won. Within a decade, it had colonized jackets, dresses, bags, and tents.

The cascade from Sundback's design extended far beyond fashion. Pressure suits for astronauts require airtight zippers—YKK's specialty zippers flew on NASA's Space Shuttle. Military parachutes depend on zippers that open under stress. Modern luggage, outdoor gear, and medical devices all rely on variants of Sundback's interlocking teeth.

YKK, founded in Japan in 1934, eventually came to dominate the industry through relentless vertical integration. They manufacture everything from the copper alloy wire to the finished zipper, controlling quality at every stage. By 2024, YKK produced over 10 billion zipper units annually—enough to circle the Earth 80 times. They hold roughly 40% of the global market by value.

The zipper's design has remained essentially unchanged for over a century. The Y-shaped channel, the interlocking teeth, the slider mechanism—all are Sundback's. Path dependence locked in his solution so completely that even plastic and nylon variants follow the same principles. The fastener that took thirty years to perfect has proven nearly impossible to improve upon.