Friedel's account is so persuasive that it is hard to imagine how the anniversary-mad modern world allowed the year 1991 to pass without centenary fireworks for what was, in that first bright flush, called the "slide fastener". They could have had installation artists zipping up the Sahara; there could have been advertisements in magazines for unique commemorative zips; there might even have been a case for a national no-zipping day.
The main beneficiary of all this would have been YKK, a Japanese company which in 1991 enjoyed what Friedel calls "international zipper pre- eminence", and produced well over a million zip miles. But the story is primarily an American one. Whitcomb Judson was a Chicago-based machine salesman who had already failed with his big hope, an absurdly elaborate hydraulic transportation system. But his basic design for a boot fastener - a series of hooks which could be swiftly yoked - truly was the mother of all zips. He patented it in 1891, but it took nearly 50 years for his little gadget to, er, catch on.
It was into America that the zip first fastened its brassy little teeth. At first it was touted as a "universal fastener", but was so universal that no one could think what to do with it. It was good for shoes, bags, packages and clothes, but hardly essential for any of them. That it won through is, Friedel argues, partly a tribute to America's tremendous marketing willpower, but mainly a function of the supple adaptability of human desire. People did not know they needed zips - they managed perfectly well with buttons and hooks. But in the end they came to want them. And so, desire being a sharper salesman than mere need, they simply had to have them. The zip industry, which settled in Hoboken, New Jersey, pushed a concept called "gaposis" - an imaginary complaint caused by ill-fitting clothes which let light and air (and eyes) in on the body underneath. Zips were promoted as the cure for this supposedly unsightly condition.
This was just typical feel-bad advertising, but Friedel is right: zips are beautiful. They both join and separate, both resist and flex. They are neat and cool, but also fierce, like jaws. And the name is a winner - the way the indolent z is so decisively sawn off by the throwaway ending. If it still went under the name "hookless hooker", the zip might not have become what it is today, "the first machine that any of us encounter in daily life".
For a long time zips were so unreliable that salesmen knew better than to go near anyone they had hoodwinked into buying one. The breakthrough came when Hoboken targeted clothing as the key, snagging on an erotic association that caught the imagination of the world. For a while it was a question of which would capitulate first: the male groin or the female backside. Friedel suggests that masculine fashion, being more conservative than the fluid, fun-loving feminine world, clung to its buttons. But he notices also, as he narrates what became known as "the battle of the fly", that there were sharper, more personal reasons for men's reticence. A certain amount of trial, and excruciating error, was enough to persuade many tailors to see the zip as a dangerous enemy.
In the end both sexes succumbed. In 1937 there were 139 million zip sales in America; by 1941 there were 500 million. The reason, Friedel proposes, was simple. Zips held out the alluring promise of "a quick and effortless disrobing", and became an emphatic part of the imagery of promiscuity and rebellion. These days, though, we notice them only when they lead nowhere, when they are just bold badges.
The best inventions, Friedel argues, are not clever responses to intractable problems. The really successful brainwaves are those that somehow create desires that only they can gratify; this is how they come to seem indispensable. Friedel admits in his first line that he had more fun researching the book than is usually supposed to attach itself to historical scholarship; but in his eagerness to insist that zips perform no useful service and are primarily a cultural fact, he downplays their genuine, if slightly boring, virtues: simple, strong, fast, tidy, and above all mass-producible.
He insists there was no demand for zips beyond novelty, documents the decades of entrepreneurial effort that were ploughed into persuading the world to like them, and concludes that our enthusiasm for zips is not utilitarian, but more like our appetite for new dances or literary forms. Yet surely a pointless gizmo that merely hooked a fashion reflex would not have endured for so long. Perhaps the truth is more tedious: that the world was happy to be zipless so long as the darn things were expensive and came apart in your hand.