How does a zip zip?

Zips are less than a hundred years old, and safe zips which did not burst open at embarrassing moments have only been around for sixty years. Before the zip, clothes and footwear had to be fastened by buttons, laces or hooks and eyes. Getting dressed was fiddly, time-consuming and likely to put you in a bad mood right at the start of the day. Then came the ‘slide fastener’, as the inventor of the first working zip called his brain wave. By today’s standards it looks clumsy and crude. It was not very reliable either. But to Whitcomb L. Judson, the Chicago engineer who came up with the idea, it was a stroke of genius.

The first zips were designed to fasten boots and shoes. It is just as well they weren’t intended for clothing because they came apart easily and tended to catch on things like socks or stockings. The real breakthrough came ten years after Judson’s slide fastener. In 1913 a Swedish engineer named Gideon Sundback had the idea of making a zip from a pair of identical locking strips attached to a flexible backing. On each locking strip there are small teeth that hook with eyes under the teeth on the other strip. Try pushing a zip together with your fingers and you will find that the teeth are too wide to slot between the adjoining ones on the other side. When you use the slide though, the teeth are splayed open to let the ones opposite lock into place. Unless you are very unlucky, a zipped zip will stay firmly closed for as long as you want it to. When you unzip it the process is reversed and the slide splays the teeth open to let the ones opposite unlock and spread apart.

 

Picture Credit : Google

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