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Plastic and nylon zippers.

A zipper, zip, or zip fastener, is a commonly used 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 items. It was perfected by Gideon Sundbäck circa 1917 based on previous less effective fasteners, but many others have made improvements and different versions of the device.

Description [link]

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.^[1] 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. "Zipper" is onomatopoeia, because it was named for the sound it makes when you use it, a high-pitched "zipper!"^{[citation needed]}

In many jackets and similar garments, the opening is closed entirely when the slider is at one of the ends of the tape. The mechanism allows for partial fastening where only some of the tape is fastened together, but various movements and pressures may move the slider around the tape. In many kinds of luggage, there are two sliders on the tape, mounted in opposite directions; the part of the zipper between them is unfastened. When the sliders are located at opposite ends of the tape, the zipper is fully unfastened; when the two sliders are located next to each other, which can be at any point along the tape, the zipper is fully closed.

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 fall 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 [link]

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, missing recognition he might otherwise have received. Forty-two 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, Judson 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.^{[citation needed]}

Gideon Sundbäck, a Swedish-American electrical engineer, was hired to work for the Universal Fastener Company in St. Catharines, Ontario in 1906. Good technical skills and a marriage to the plant-manager's daughter Elvira Aronson led Sundbäck 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.^{[citation needed]}

Gideon Sundbäck increased the number of fastening elements from four per inch (about one every 6.4 mm) to ten or eleven (around every 2.5 mm), 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. Gideon Sundbäck 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, Sundbäck's machinery was producing a few hundred feet (around 100 meters) of fastener per day.^{[citation needed]}

Zipper slider brings together the two sides

The popular "zipper" name came from the B. F. Goodrich Company in 1923^[2]; they opted to use Gideon Sundbäck'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. It was almost twenty years before the fashion industry began seriously promoting the novel closure on garments.^{[citation needed]}

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 1937 in the "Battle of the Fly", after French fashion designers raved over zippers in men's trousers. Esquire 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."^{[citation needed]}

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 on clothing, luggage, leather goods, and various other objects.^[3]

Types [link]

A coil zipper with its slider removed.

• Coil zippers now form the bulk of sales of zippers worldwide. The slider runs on two coils on each side; the "teeth" are formed by the windings of 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 also known as a nylon zipper.
• Invisible zippers' have the teeth hidden behind a tape, so that the zipper is "invisible". The tape's color matches the garment's, as does the slider's. 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 because the appearance of a button down shirt can be maintained, while providing a quick and easy fastening 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 molded into shape and set on the zipper tape at regular intervals. Metal zippers are made in brass, aluminum 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 jeans-wear, work-wear, 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 thermoplastic polymers are used as well, such as 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 luggage.

Air tightness and water tightness [link]

Waterproof zipper on a diving dry suit. The exterior metal segments clamp the waterproof sheeting over the concealed zipper teeth. The zipper teeth are not visible in this image (obscured by the edges of the waterproof sheet).

Airtight zippers were first developed by NASA for making high-altitude pressure suits and later space suits, capable of retaining air pressure inside the suit in the vacuum of space.

The airtight zipper is built like a standard toothed zipper, but with a waterproof sheeting (which is made of fabric-reinforced polyethylene and is bonded to the rest of the suit) wrapped around the outside of each row of zipper teeth. The sheeting is crimped in place around each zipper tooth by using a C-shaped metal clip on the outside. (These externally-visible opposing rows of clips are the metal runners on which the slider moves.) When the zipper is closed, the two facing sides of the plastic sheeting are squeezed tightly against one another (between the C-shaped clips) both above and below the zipper teeth, forming a double seal.^[4]

This double-mated surface is good at retaining both 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 minimal flex or stretch. They are hard to open and close because the zipper anvil must bend apart teeth that are being held under tension. They can also be derailed (and damage 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 hazmat suits.

A less common water-resistant zipper is similar in construction to a standard toothed zipper, but includes a molded plastic ridge seal similar to the mating surfaces on a ziploc bag. Such a zipper is easier to open and close than a clipped version, and the slider has a gap above the zipper teeth for separating the ridge seal. This 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. Ridge-sealed zippers are sometimes seen on lower cost surface dry suits.

Components [link]

Components of a zipper

The components of a zipper are: top tape extension top stop slider pull tab tape chain width bottom stop bottom tape extension single tape width insertion pin boll retainer box reinforcement film

Manufacturing [link]

According to an article by Forbes,^[5] the zipper market in the 1960s was dominated by two major companies: Talon Zipper (USA) and Optilon (Germany). However, a Japanese manufacturer YKK Group grew to become the industry giant by the 1980s. As of 2003^[update], YKK held 45% of the world market share, followed by Optilon (8%) and Talon (7%). A majority of the rest was estimated to be divided among more than 1,000 Chinese companies.

On the other hand, an article in 2005 by The Guardian reported that China had 80% of the international market. Most of them are manufactured in Qiaotou, Yongjia County.^[6]

Patents [link]

1917 Gideon Sundbäck patent:

• 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 [link]

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

See also [link]

• Zipper storage bag

References [link]

• 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

1. ^ "YKK Fastening Products Group". Ykkfastening.com. Archived from the original on 2010-06-17. https://web.archive.org/web/20100617014018/https://www.ykkfastening.com/global/products/zs/structure.html. Retrieved 2011-07-14. 
2. ^ https://www.csmonitor.com/Innovation/Pioneers/2012/0424/Gideon-Sundback-At-first-the-world-shunned-the-zipper
3. ^ Mary Bellis (2010-06-16). "History of the zipper". About.com Inventors. https://inventors.about.com/library/weekly/aa082497.htm. Retrieved 2011-07-14. 
4. ^ Drysuits: Zippers, Seals, Valves and Maintenance, NJScuba.net. Illustrated dissection of a dry-suit zipper.
5. ^ Benjamin Fulford (2003-11-24). "Zipping Up the World". Forbes.com. https://www.forbes.com/global/2003/1124/089.html. Retrieved 2012-04-24. 
6. ^ Jonathan Watts (2005-05-25). "The tiger's teeth". The Guardian. https://www.guardian.co.uk/business/2005/may/25/china.g2. Retrieved 2012-04-24. 

External links [link]

Wikimedia Commons has media related to: Zippers

• How Zippers Work by S. M. Blinder, the Wolfram Demonstrations Project.
• The History of the Zipper.

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