TP ANALYSES - FLY ZIPPER

FLY ZIPPER

A zipper, zip, fly or zip fastener, formerly known as a clasp locker, is a commonly used device for binding the edges of an opening of fabric or other flexible material, as on a garment or a bag. 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. Its invention is based on interlocking teeth. Initially it was called the “hookless fastener” and was later redesigned to become more reliable.

Nylon plastic zippers.

Description

The bulk of a zipper/zip consists of two rows of protruding teeth which may be made to interdigitate, linking the rows, 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. 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. The word Zipper is onomatopoetic, because it was named for the sound the device makes when used, a high-pitched zip.

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, or on the front, back or side of a dress or skirt to facilitate dressing.
• Attach or detach a separable part of the garment to or from another, as in the conversion between trousers and shorts or the connection or 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.

Zipper slider brings together the two sides

Types

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. Coil zippers are made of polyester coil and are thus also termed polyester zippers. Nylon was formerly used and though only polyester is used now the type is still also termed 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.
• Reverse coil zippers are a variation of the coil zipper. A reverse coil zipper is exactly that - the coil is on the reverse (back) side of the zipper and the slider is engineered to work on the flat side of the zipper (normally the back, now the front). Unlike an invisible zipper where the coil is also on the back, the reverse coil shows stitching on the front side and the slider will accommodate a variety of pulls (the invisible zipper requires a small, tear-drop pull due to the small slider attachment). Water resistant zippers are generally configured as reverse coil so that the pvc coating can cover the stitching.
• 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 described types.
• Closed-ended zippers are closed at both ends; they are often used in luggage.
• Magnetic zippers allow for one-handed closure and are used in sportswear.

Components

The components of a zipper are: Top Tape Extension (The fabric part of the zipper, that extends beyond the teeth, at the top of the chain.) Top Stop (Two devices affixed to the top end of a zipper, to prevent the slider from coming off the chain.) Slider (The device that moves up and down the chain to open or close the zipper.) Pull Tab (The part of the slider that is held to move the slider up or down.) Tape Width (Refers to the width of the fabric on both sides of the zipper chain.) Chain (The continuous piece that is formed when both halves of a zipper are meshed together) and Chain Width (Refers to the specific gauge of the chain) Bottom Stop (A device affixed to the bottom end of a zipper, to prevent further movement of the half of the zipper from separating.) Bottom Tape Extension (The fabric part of the zipper, that extends beyond the teeth, at the bottom of the chain.) Single Tape Width (Refers to the width of the fabric on one side of the zipper chain.) Insertion Pin Boll (A device used on a separating zipper whose function is to allow the joining of the two zipper halves.) Retainer Box (A device used on a separating zipper whose function is to correctly align the pin, to begin the joining of the zipper halves.) Reinforcement Film (A strip of plastic fused to each half of the zipper tape to allow a manufacturer to electronically "weld" the zipper onto the garment or item that is being manufactured, without the need of sewing or stitching.)

1. 

Things you’ll need for sewing a fly zipper

v  Pants pattern with fly

v  Pants fabric

v  Zipper (20 cm)

v  Tracing material (e.g. paper) to make your fly template

v  Chalk or other fabric marker

v  Sewing pins and thread

v  Sewing machine

v  Iron

v  Serger (optional)

Guidelines on how to sew a fly zipper

Cut your pants’ front

Sew any darts or pleats

Mark the centre front line on your pants, this line is marked on your pattern pieces.  

Sew the fronts together along the centre front line. From the bottom of the zipper down, sew with a regular stitch. From the bottom of the zipper and up, use a basting stitch. The point here is to baste your fly shut. A short stitch will make it more difficult to rip out later.

Place pants fronts on table, wrong side up. Fold both fronts to the left, leaving one fly extension pointing to the right. Pin zipper in place, with side lining up to centre front. You will be sewing the side furthest from centre front.

Use zipper foot to stitch close to the zipper on the side sticking out from the pants fronts.

Turn zipper over. Fold the extra fabric down the zipper. The extra fabric may extend under centre front. Pin and stitch about 1mm from the zipper. This holds that extra fabric in place.

Use zipper foot to stitch close to the zipper

Flip pants so that pants fronts are both on your right. They were on the left.

Turn zipper over. Make sure that it’s flat.

Pin zipper to the fly extension on your left.

Using a zipper foot, sew close to the zipper.

Now your zipper is attached to both fly extensions, but no sewing shows on the front of the pants.

Turn your pants over so they are right side up.

Butt fly template against the centre front seam. If you do not have a fly template, you can copy one from a pair of pants.

Trace around fly template.

Pin pants front to the extension underneath. Make sure everything is nice, flat and smooth.

Using your usual foot, sew fly stitches in place. Note: always start at the bottom because if you start on top the fabric tends to get twisted.

This is how it should look like.

Press.

Admire your fly.

Cut a piece of fabric (10x20cm) for a fly shield.

Fold fly shield in half, wrong sides together.

Press.

Overlock the edges of the fly shield. Optional, cut of some fabric from the bottom curve to make a rectangular fly shield. If you do not have a serger, you can overlock with a sewing machine. Use your overlock foot and zigzag stitch.

Pin your zipper shield to the extension on the under lapped side of the fly.

Fold your pant fronts off to the side, so that you only sew-through the fly shield extension.

This is how your fly is supposed to look like from the wrong and right sides.