How Gideon Sundback Perfected the Zipper

Though commonplace today, National Inventors Hall of Fame® Inductee Gideon Sundback’s Hookless Fastener No.2 zipper design received a lukewarm reception in 1914.

Not only were buttons and clasps more popular fastening solutions at the time, but earlier zipper designs were simply unreliable and at times downright annoying to use. Unlike these earlier models, however, Sundback’s design would prove efficient and easy to use. His improved system “increased the number of fastening elements from four per inch to 10 or 11.” Additionally, his design “added an indent and bump to each tooth,” so that the teeth could interlock and could be connected again by moving the slider.

In 1917, a New York City tailor named Robert J. Ewig began using Sundback’s hookless fastener to make money belts (essentially fanny packs). During WWI, these money belts became an instant favorite for U.S. sailors, whose uniforms at the time were made without pockets. By 1918, the Navy purchased 10,000 fasteners to incorporate in their flight suits.

Continuous Improvement

Though Sundback’s design was a clear improvement over previous zipper designs, throughout his life, he continued to innovate. Central to the zipper’s later economic success was the machine Sundback built in 1923, the ‘S-L’ or scrapless machine, made specifically to manufacture his zipper.

According to Henry Petroski, the Aleksander S. Vesic Distinguished Professor Emeritus at Duke University, this ingenious contraption took a Y-shaped wire, and cut scoops and punched dimples into the material. Once this was completed, each scoop was then taped to cloth — thereby creating a “continuous zipper chain.” During just the first year of the machine’s operation, the S-L was producing hundreds of feet of fasteners per day.

In an interview with Carnegie Mellon University, Sundback’s son spoke about how his father was a hard worker, and how he continued to improve on the design of the zipper throughout his life. “My father was totally interested in quality; this was his hallmark. He didn’t quit when he had something partially done,” Eric said. “Perfecting [the zipper] was what kept him going for a long time.”

The Zipper Gets Its Name

The hookless fastener’s use in WW1 earned it widespread public interest. Because of this, the B.F. Goodrich company began attaching the fasteners to their rubber boots, allowing a wearer to open and close the boots with just one hand. Inspired by the sound the fastener made when it was used, they named their boot the “Zipper.”

The manufacturing of zippers has become big business and last year, YKK, the world’s leading zipper manufacturer, posted $10 billion in annual revenue.

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