Zipper

A zip (American English: zipper or (rarely) zip fastener) is a popular device for temporarily joining two edges of fabric. It is used in clothing (e.g., jackets and jeans), luggage and other bags, sporting goods, camping gear (e.g., tents and sleeping bags), and other daily use items.

Description

The bulk of a zipper consists of two strips of fabric tape, each affixed to one of the two pieces to be joined, carrying from tens to hundreds of specially shaped metal or plastic teeth. These teeth can be either individual or shaped from a continuous coil, and are also referred to as elements.[2] The slider, operated by hand, moves along the rows of teeth. Inside the slider is a Y-shaped channel that meshes together or separates the opposing rows of teeth, depending on the direction of the slider's movement.

Some zips have two slides, allowing variation in the opening's size and position. In most jackets and similar garments, the opening is closed entirely when one slide is at each end. In most baggage, the opening is closed entirely when the two slides are next to each other at any point along the zipper.

Zippers may:

increase or decrease the size of an opening to allow or restrict the passage of objects, as in the fly of trousers or in a pocket.
join or separate two ends or sides of a single garment, as in the front of a jacket, dress or skirt.
attach or detach a separable part of the garment to or from another, as in the conversion between trousers and shorts or the connection / disconnection of a hood and a coat.
decorate an item.

These variations are achieved by sewing one end of the zipper together, sewing both ends together, or allowing both ends of the zipper to come completely apart.

A zipper costs relatively little, but if it fails, the garment may be unusable until the zipper is repaired or replaced—which can be quite difficult and expensive. Problems often lie with the zipper slider; when it becomes worn it does not properly align and join the alternating teeth. If a zipper fails, it can either jam (i.e. get stuck) or partially break off.

History

Elias Howe, who invented the sewing machine, received a patent in 1851 for an "Automatic, Continuous Clothing Closure". Perhaps because of the success of his sewing machine, he did not try to seriously market it, and missed out on any recognition he might otherwise have received. Forty-four years later, Whitcomb Judson, who invented the pneumatic street railway, marketed a "Clasp Locker". The device was similar to Howe's patent, but actually served as a (more complicated) hook-and-eye shoe fastener. With the support of businessman Colonel Lewis Walker, Whitcomb launched the Universal Fastener Company to manufacture the new device. The clasp locker had its public debut at the 1893 Chicago World's Fair and met with little commercial success.

Swedish-born Gideon Sundback, an electrical engineer, was hired to work for the Universal Fastener Company. Good technical skills and a marriage to the plant-manager's daughter Elvira Aronson led Sundback to the position of head designer. After his wife's death in 1911, he devoted himself to the worktable, and by December 1913 had designed the modern zipper.

Sundback increased the number of fastening elements from four per inch to ten or eleven, introduced two facing rows of teeth that pulled into a single piece by the slider, and increased the opening for the teeth guided by the slider. The patent for the "Separable Fastener" was issued in 1917. Sundback also created the manufacturing machine for the new device. The "S-L" or "scrapless" machine took a special Y-shaped wire and cut scoops from it, then punched the scoop dimple and nib, and clamped each scoop on a cloth tape to produce a continuous zipper chain. Within the first year of operation, Sundback's machinery was producing a few hundred feet of fastener per day.

The popular "zipper" name came from the B. F. Goodrich Company; they opted to use Sundback's fastener on a new type of rubber boots (or galoshes) and referred to it as the zipper, and the name stuck. The two chief uses of the zipper in its early years were for closing boots and tobacco pouches. However, it was almost twenty years before the fashion industry began seriously promoting the novel closure on garments.

In the 1930s, a sales campaign began for children's clothing featuring zippers. The campaign praised zippers for promoting self-reliance in young children by making it possible for them to dress in self-help clothing. The zipper beat the button in the 1937 in the "Battle of the Fly", after French fashion designers raved over zippers in men's trousers. Esquire magazine declared the zipper the "Newest Tailoring Idea for Men" and among the zippered fly's many virtues was that it would exclude "The Possibility of Unintentional and Embarrassing Disarray."

The most recent innovation in the zipper's design was the introduction of models that could open on both ends, as on jackets. Today the zipper is by far the most widespread fastener, and is found almost everywhere, installed on clothing, luggage, leather goods, and various other objects.^[1]

Types

Coil zippers now form the bulk of sales of zippers worldwide. The slider runs on two coils on each side; the "teeth" are the coils. Two basic types of coils are used: one wonly polyester is used now, the type is still known as a nylon zipper.
Invisible zippers' teeth are behind the tape. The tape's color matches the garment's, as does the slider, so that, except the slider, the zipper is "invisible". This kind of a zipper is common in skirts and dresses. Invisible zippers are usually coil zippers. They are also seeing increased use by the military and emergency services due to the fact that the appearance of a button down shirt can be maintained, while having a quick and easy system.
Metallic zippers are the classic zipper type, found mostly in jeans today. The teeth are not a coil, but are individual pieces of metal moulded into shape and set on the zipper tape at regular intervals. Metal zippers are made in brass, aluminium and nickel, according to the metal used for teeth making. All these zippers are basically made from flat wire. A special type of metal zipper is made from pre-formed wire, usually brass but sometimes other metals too. Only a few companies in the world have the technology. This type of pre-formed metal zippers is mainly used in high grade jeanswear, workwear, etc., where high strength is required and zippers need to withstand tough washing.
Plastic-molded zippers are identical to metallic zippers, except that the teeth are plastic instead of metal. Metal zippers can be painted to match the surrounding fabric; plastic zippers can be made in any color of plastic. Plastic zippers mostly use polyatomic resin though otherthylene.
Open-ended zippers use a "box and pin" mechanism to lock the two sides of the zipper into place, often in jackets. Open-ended zippers can be of any of the above specified types.
Closed-ended zippers are cl

The airtight zipper is built like a standard toothed zipper, but with the zipper teeth wrapped in a fabric-reinforced polyethylene sheeting. The sheeting is then crimped around each zipper tooth using a C-shaped metal clip. As the zipper is closed, the facing edges of the plastic sheeting are pressed together between the C-shaped clips, both above and below the zipper teeth.

This double-mated surface is good at both retaining vacuum and pressure, but the fit must be very tight to press the surfaces together firmly. Consequently these zippers are typically very stiff when zipped shut and have very minimal flex or stretch. They are hard to open and close because the zipper anvil must bend apart teeth that are being held together by the tough plastic sheeting. They can also be derailed and chew up the sealing surfaces if the teeth are misaligned while straining to pull the zipper shut.

These zippers are very common where airtight or watertight seals are needed, such as on scuba diving dry suits, ocean survival suits, and on hazmat suits.

A second, less common water-resistant zipper is similar in construction to a standard toothed zipper, plus a molded plastic ridge seal similar to the mating surfaces on a ziploc bag. It is much easier to open and close, and the slider has a gap above the zipper teeth for separating the ridge seal. However, this ridge seal is structurally weak against internal pressure, and can be separated by pressure within the sealed container pushing outward on the ridges, which will simply flex and spread apart, potentially allowing air or liquid entry through the spread-open ridges. It is sometimes seen on lower cost surface dry suits.

Components

The components of a zipper are:

1 - Stupid you
2 - top stop
3 - slider
4 - pull tab
5 - LOL
6 - chain width
7 - bottom stop
8 - bottom tape extension
9 - single tape width
10 - insertion pin
11 - Hello
12 - reinforcement film

Manufacturing

Japan makes 90% of the world's zippers.^[2] A large part of these are manufactured by YKK, which has production facilities in 68 countries and the world’s largest zipper manufacturing center in Macon, Georgia, USA, with 900 employees.[3] Almost all of the rest are made in South Asia and East Asia. Major zipper manufacturing countries in South Asia are now Bangladesh, India and Pakistan.

Patents

25 November 1851 U.S. patent 8,540: "Fastening for Garments & c."
29 August 1893 U.S. patent 504,037: "Shoe fastening"
29 August 1893 U.S. patent 504,038: "Clasp Locker or Unlocker for Shoes"
31 March 1896 U.S. patent 557,207: "Fastening for Shoes"
31 March 1896 U.S. patent 557,208: "Clasp-Locker for Shoes"
29 April 1913 U.S. patent 1,060,378: "Separable fastener"
20 March 1917 U.S. patent 1,219,881: "Separable fastener"
22 December 1936 U.S. patent 2,065,250: "Slider"

Alternatives

Buckle
Button
Safety pin
Shoelaces
Snap fasteners (also known as poppers and press studs)
Velcro

References

Henry Petroski: The Evolution of Useful Things (1992); ISBN 0-679-74039-2
Robert Friedel: Zipper: An Exploration in Novelty (W. W. Norton and Company: New York, 1996); ISBN 0-393-31365-4

^ [http://inventors.about.com/library/weekly/aa082497.htm History of the zipper
^ At least one source disputes this assessment, saying that 80% of the world's zippers come from China, and this includes numerous zippers from Qiaotou, Zhejiang Province.[1]