Today, the zip is by far the most widespread fastener, used on clothing, luggage, upholstery and various other objects.
Iterative improvement
In 1914 the US Patent Office received an application from Gideon Sundbäck, a Swedish-American inventor. He had refined an idea for a hookless fastener, based on interlocking teeth, that had been circulating among engineers for over twenty years. Until Sundbäck, nobody had managed to get it quite right. They were either too weak, or wore out too soon.
One small change
Sundbäk’s innovation was positioning a dimple on the underside of each tooth, and a nib that would sit fast within the dimple of the tooth above it, on the top. The resulting join between the two rows of teeth was strong because no single tooth has enough vertical movement to unclasp.
Rapid adoption
B.F. Goodrich was the first company to put Hookless Fastener No.2 to commercial use, using it on a range of rubber overshoes in 1923. The overshoes eventually gave their name to the fastening – Zipper. Within a couple of years they were being added to children's garments, after manufacturers realised they enable youngsters to dress themselves.