The zipper is a device commonly used as a closure on apparel and other items. Most people in the western world use zippers every day. But, how does a zipper actually work?
How a zipper works
The zipper is deceptively simple in its structure. The two primary elements of the zipper are the hook and the wedge. A “hook” is any curved item meant to grab and hold any other item. A “wedge” is an item with a slanted surface, designed to push something aside. For example, a doorstop is a wedge that holds the door open by exerting force upward to the base of a door to hold it in place.
Each zipper has two rows of multiple “teeth”, mounted across from one another. Each tooth has a hook on it and the hooks are alternated with hollow areas. The two rows of teeth are positioned offset from one another so that each hook is across from a hollow and vice versa. A zipper is closed when the hooks in the teeth on one side of the zipper are hooked into the hollow areas between the teeth on the other side. The “slide” or pull contains wedges that push the hooks into the hollow areas, closing the zipper.
So, a slide starts at the base of a zipper and as it is pulled upward the two strips of teeth pass through it. They must pass through at a specific angle in order for the zipper to be closed. As they move through the slide the wedges push the hooks toward the hollows on the opposite set of teeth. Once they are pushed together, they are tightly connected in sequence. In order for a zipper to work, each tooth and hollow must be identical in both size and shape.
To “unzip” the zipper, the slide is moved in the opposite direction. Once again, the wedges in the slide push against the hooks, this time detaching them. A zipped zipper is quite strong if it has been well designed, and it is fast to open and close.
Stops are the pieces that keep the zipper slide from leaving the end of the row of teeth. The tape is the cloth or woven part of the zipper to which the teeth are attached. Coil zippers use a continuous coil for the teeth of the zipper instead of separate pieces.
A little zipper history
Patented in the late 1800s, the zipper is a simple device now used everyday by people worldwide. The inventor, Whitcomb L. Judson was a fan of gadgets and machines and invented several labor-saving items. His invention was not called a zipper; rather he dubbed it the “clasp locker”. Inventor Elias Howe had patented a similar closure device earlier in the century, but he never brought it to market. The device was given the name zipper by the B.F. Goodrich company which they used on some rubber boots in the early 1900s. In 1937, it was first used as a closure for men’s trousers.
While the zipper is not a critical or revolutionary tool, it is highly useful. Today, zippers are found on clothing and footwear, tents, sleeping bags, backpacks, purses and suitcases. Zippers today are still sometimes made from metal, but are usually made of plastic or nylon.
