Zip fastener is a fastening device in which two rows of teeth and sockets are brought together in such a way that they interlock. Whitcomb Judson invented the first zip in 1893.
The Zip Fastener an improved method of fastening garments
Metal zips have lines of tiny teeth, while plastic zips contain small loops on each side.
Do you know how a zip fastener works?
When you pull the side of the zip fastener up, it pushes the teeth or loop together. Beneath each tooth in a metal zip fastener is a small space. The slide is narrow at the bottom so that it forces the teeth together as the zip is pulled up. The teeth on one side fit between the teeth on the other side. As they come together, each tooth slips into the socket under the tooth above and the zip stays closed. As the slide moves down, a divider at the top of the slide pulls the teeth apart.
The top pieces and a bottom piece at the ends of the fastener stop the slide from coming off, though some zips are made to separate completely by pulling one line of teeth out of the bottom piece. Plastic zips have two spiral coils instead of lines of teeth but the principle on which they work is the same.