Zip Attachments and Fasteners. Introduction to Zips.(Refer to Single Page Visual) Types of zips There are three basic types of zips: conventional, opened, and concealed. Conventional zips are closed at one end and sewn into a seam that is stitched to the zip placket. Opened zips are open at both ends and are sewn into a scam that will open completely. The concealed zip is constructed so as to disappear into a scam; like conventional zips, it has one closed end. A special zipper foot must be used to insert a concealed zip. All zips consist of' either a chain of metal or plastic teeth or a synthetic coil joined to fabric tapes. Coils are essentially tightly twisted spirals of polyester or nylon. Zips are made in many weights and sizes. Since metal and synthetic zips are about equal in strength and performance, the choice is largely a matter of personal preference. Synthetic zips are lighter in weight and usually more flexible than metal and are available in many colors. Metal zips come in heavy duty forms (see Zip chart) which are suitable for jeans and work clothes. Zip tapes are woven from cotton or a blend or cotton and nylon or polyester. In some zip brands, a sewing guideline is woven into the tapes to direct stitching; in brands without a guideline, the herringbone weave of the zip tape can be used as a stitching guide. Zips are opened and closed by means of a slider, with a handle-like tab that moves it up and down. Top and bottom stops keep the slider from running of the zip. If fabric or thread jams a coil zip, fold the zip crosswise and separate the coil. Close the coil by moving the slider to the bottom stop and then returning it to the top. If a metal zip begins to stick, it can be lubricated with candle wax. >Centred zip The method for applying a centred zip is the same regardless of the garment type; the only variable is in the placement of the zip below the top edge of the garment. Where it is placed depends on how this edge will be finished. If a facing is to be used, you should place the top stop of the zip 10 mm. (3/8 in.) below the seam line of the garment. This allows extra space for turning down the facing and for attaching a hook and eye. If the finish does not require that seam allowances be turned down, as with a waistband or standing collar, place the top stop just below the seam line (a bare 6 mm.- 1/4in.). All work is done on the inside of the garment except for topstitching. Work from bottom to top of placket, in both preliminary tacking and topstitching. Keep the zip dosed, except in Step 3, with pull tab up. >Lapped zip A lapped zip is applied the same way regardless of garment type ; the only variable is in the placement or the zip in relation to the garment edge. If there will be a facing finish place the top stop 10 mm. (3/8in. ) below the seam line. If the garment will have a waistband or standing collar, place the top stop just below the seam line. Do all work on inside of garment, except topstitching; keep zip closed throughout application. Work from bottom to top on all steps; this will ensure that the lap goes in the proper direction on the garment. >Concealed zip The concealed zip is different from a conventional zip in both appearance and installation. When this zip is closed, all that shows on the garment is a plain seam and tiny pull tab. Concealed zips are applied to an open scam, to scam allowances only-there is no stitching on the outside of the garment. They can be used wherever conventional zips are used. Manufacturers supply a special zipper foot to sew in this zip. It is. impossible to apply a synthetic coil concealed zip without one, although a metal concealed zip can be applied with a regular zipper foot.