Zipper

A zipper (English: zip fastener or zip) 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, because it's stronger than the alternatives.

Descriptions

The bulk of a zipper consists of two strips of fabric tape, each affixed to one of the two pieces to be joined, carrying tens or 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". [http://www.ykkfastening.com/global/products/zs/structure.html] 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 its movement. The friction and vibration of the slider against the teeth causes a characteristic buzzing noise, which is probably the origin of the name "zipper". The name also may have originated in the greater speed and ease with which the two sides of a zipper can be joined, compared to the time needed for fastening laces or buttons.

Some zippers 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 the size of an opening to allow 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
* 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.

History

An early device superficially similar to the zipper, "an Automatic, Continuous Clothing Closure", was patented in the United States by Elias Howe in 1851. Unlike the zipper, Howe's invention had no slider; instead a series of clasps slid freely along both edges to be joined, with each clasp holding the two sides together at whichever pair of points along them it was located. The clasps were joined together by a string, which, when pulled taut, caused the clasps to be evenly spaced along the closure, thus holding the two edges together. Pulling in the other direction caused the clasps to become bunched up at one end, by which means the device was opened.

The true zipper was the product of a series of incremental improvements over more than twenty years, by inventors and engineers associated with a sequence of companies that were the progenitors of Talon, Inc. This process began with a version called the "clasp locker", invented by Whitcomb L. Judson of Chicago (previously of Minneapolis and New York City), and for which a patent (US patent|504038|No. 504,038) was first applied on Nov. 7, 1891. It culminated in 1914 with Gideon Sundback's invention of the "Hookless Fastener No. 2", the first version of the zipper without any major design flaws and essentially indistinguishable from modern zippers.

Initial versions of the zipper were based on the "hook and eye" principle, rather than on interlocking teeth, and tended to come apart easily. Some versions depended on constant pressure from one side of the joined fabric in order to hold together at all, which limited applications. In the 1891 version, the slider detached entirely from the zipper when not being used to open or close.

Judson, together with business partner Harry Earle, founded the first incarnation of what was to eventually become Talon Inc., in Chicago in 1894, as the Universal Fastener Company. The design deficiencies, combined with difficulties in getting the machinery needed for mass production to work, prevented the early devices from reaching market, which led to financial hardships for the company. This in turn led to a series of reorganizations and name changes, as well as relocations, first to Catasauqua, Pennsylvania; then to Elyria, Ohio; Hoboken, New Jersey; and finally Meadville, Pennsylvania.

Gideon Sundbäck, a Swedish-born American immigrant, joined the company, then called the Automatic Hook and Eye Company, in Hoboken, in 1906. At that time the company's product, still based on hooks and eyes, was called the "C-curity Fastener". Sundback developed an improved version of the C-curity, called the "Plako", but it too had a strong tendency to pull apart, and wasn't any more successful than the previous versions. Sundback finally solved the pulling-apart problem in 1913, with his invention of the first version of the zipper based on interlocking teeth, the "Hookless Fastener No. 1".

That version, however, had a tendency to wear out quickly, and again was not a commercial success. Finally, in 1914 Sundback developed another version based on interlocking teeth, the "Hookless No. 2", which solved the last remaining major design defect, and opened the way to commercial success. The principle is, each tooth is punched to have a dimple on its bottom and a nib or conical projection on its top. The nib atop one tooth engages in the matching dimple in the bottom of the tooth that follows it on the other side as the two strips of teeth are brought together through the two Y channels of the slider. The teeth are crimped tightly to a strong fabric cord that is the selvage edge of the cloth tape that attaches the zipper to the garment, with the teeth on one side offset by half a tooth's height from those on the other side's tape. They are held so tightly to the cord and tape that once meshed there is not enough play to let them pull apart - - a tooth cannot rise up off the nib below it enough to break free, and its nib on top cannot drop out of the dimple in the tooth above it. The classic zipper was made of a brass alloy, a metal that has low friction and is long-wearing.

Sundback's invention of the Hookless No. 2 took place while he was working for the Hookless Fastener Company in Meadville, which had previously been set up to manufacture the Hookless No. 1. Depending on which improvement one wants to consider to constitute the "invention" of the zipper, the zipper was invented either in Meadville, Chicago, or one of the other previously mentioned cities. The B. F. Goodrich Company coined the name Zipper in 1923 for the line of rubber overshoes that it made using the fastener. The name slowly came to be associated with the fastener itself, and eventually acquired generic status.

The zipper slowly became popular for children's clothing and men's trousers in the 1920s and 1930s. In the early 1930s the haute couture designer Elsa Schiaparelli featured zippers in her avant-garde gowns, helping it to become acceptable in women's clothing. In 1934, Tadao Yoshida founded a company called San-S Shokai in downtown Tokyo. Later, this company would change its name to YKK nihongo|"Yoshida Kōgyō Kabushiki-gaisha"|吉田工業株式会社 and become the world's largest manufacturer of zippers and fastening products. By World War II, the zipper had become widely used in Europe and North America, and after the war quickly spread through the rest of the world.

Clergy in the 1920s and 1930s described zippers as allowing one to take one's clothes off too quickly, thus hastening illicit sexual activity. Clothing with zippers was seen as inappropriate to be worn by women because of this belief, and was not fully adopted until the late 1950s.Fact|date=December 2007

Today, such global companies as YKK, Olympic Zippers Ltd, Opti, TALON, Ideal, NEO, KCC Group, and Tex Corp, make various types of zippers including "invisible" zippers, metallic zippers, and plastic zippers.

On a CBC-produced miniseries aired in January 2007, "The Greatest Canadian Invention"; the Zipper placed at No. 8 on the list. It qualified because Sundback had been president of a Canadian-based company that was one of the earliest manufacturers of the zipper.

Over a number of years the zipper has become extremely common on many of the clothing items that are worn by everyday people all over the world.

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 with coils in spiral form, usually with a cord running inside the coils; the other with coils in ladder form, also called the Ruhrmann type. This second type is now used only in a few parts of the world, mainly in South Asia. Coil zippers are made of polyester coil and are thus also known as polyester zippers. Nylon was formerly used and though only polyester is used now, the type is still known as a nylon zippers.
* 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 or to be precise polyester zipper.
* 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. These type of pre-formed metal zippers are 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 polyacetal resin though other resins are used too like polyethylene.
* 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 closed at both ends; they are often used in baggage.

Components

The components of a zipper are:
* 1 - top tape end
* 2 - top stop
* 3 - slider
* 4 - puller
* 5 - tape
* 6 - spiral width
* 7 - bottom stop
* 8 - bottom tape end
* 9 - single tape width
* 10 - pin
* 11 - box
* 12 - reinforcement

Manufacturing

Japan makes 68% of the world's zippers. [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. [http://www.guardian.co.uk/g2/story/0,,1491380,00.html] ] 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. [http://www.ykk-usa.com/] Almost all of the rest are made in Southeast Asia.fact|date=February 2008 Major zipper manufacturing countries in Southeast Asia are now Bangladesh, China and India. These countries are not only manufacturing zippers for domestic use and use in exported products but are exporting zippers directly to other countries as well.Fact|date=February 2007
TALON still exists as an American brand, now owned by TagIt Pacific of USA.Tag It recently changed its name to Talon International Inc.

Patents

* 25 November 1851 US patent|8540: "Fastening for Garments & c."
* 29 August 1893 US patent|504037: "Shoe fastening"
* 29 August 1893 US patent|504038: "Clasp Locker or Unlocker for Shoes"
* 31 March 1896 US patent|557207: "Fastening for Shoes"
* 31 March 1896 US patent|557208: "Clasp-Locker for Shoes"
* 19 April 1913 US patent|1060378: "Separable fastener"
* 20 March 1917 US patent|1219881: "Separable fastener"
* 22 December 1936 US patent|2065250: "Slider"

Alternatives

* Buckle
* Button
* Rack and pinion
* 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

External links

* [http://www.withgoodreasonradio.org/archives/2007/jan07wgr.html Zipper! - With Good Reason by VFH Radio] Robert Friedel and Alexander Horniman (University of Virginia) examine how the zipper illustrates the limitations and expectations of technology.
* [http://www.industrie.coats.de/zip/zipabc/ The ABC of zip fasteners] information and images about the types and components of a zipper.
* [http://demonstrations.wolfram.com/HowZippersWork/ How Zippers Work] by S. M. Blinder, The Wolfram Demonstrations Project.