The Zip Fastener - IELTS Listening Answers & Explanations

LECTURER: I think you all have a copy of the printed notes and diagram ... but I should point out before we go any further that there are a few mistakes in those notes, so please correct any you notice as we go along. Right, as you can see, we are going to be looking at the zip, or zipper as it's known in the US, which is where it had its origins in 1851. In fact, it was initially given the rather less catchy name of the Automatic Continuous Clothing Closure by the person that invented it: Elias Howe, who also designed the first sewing machine. It wasn't until 1893, though, that someone actually tried to market the zip, when Whitcomb Judson, another American inventor, took what he called the Clasp Locker to the World's Fair held that year in the US. His hook and eye system was a commercial disaster, and it was another fifteen years before the buying public began to take an interest: this time a more reliable model with facing sets of teeth named the Hookless Fastener, designed by a Swedish engineer called Gideon Sundback. Attached to clothing, purses and other items, it sold quite well. Gradually this new alternative to buttons caught on, as people realized the advantages of a fastener that only needed one hand to operate, that children could use, that left no visible gaps, and so on. The British firm Kynoch began producing and selling the Ready Fastener in large numbers in 1919, and a few years later the Zipper, designed and given its modern American name by BF Goodrich, made Mr Goodrich extremely rich indeed.

If its use in trousers was a major factor in establishing the zip as a fashion icon, despite its occasional tendency to trap parts of the wearer's anatomy, another major breakthrough came with the separable zip: the kind that opens at both ends. This type, still widely used in a range of items from jackets to tents, is shown in the diagram. Let's look first at the right-hand side of the illustration, at the material attached to the item of clothing, the bag or whatever. This is the tape, which is usually made of fairly tough fabric. At the end of that there's what is known as the heat seal patch: the cotton and nylon laminated material used to reinforce the tape. Now alongside the heat seal patch is a small piece of metal, used only on a separating zip, whose function is to enable the two halves of the zip to join. This is known as the 'pin'. Opposite that, on the other half of the zip in the diagram, is a device which correctly aligns the pin. The 'box', as it's called, begins the joining of the zip halves. Running up the inside edge of each half are dozens, possibly hundreds, of metal 'teeth', each of which has a small hook and an equally tiny hollow. Moving up and down the teeth, to open and close the zip, is a piece of metal called the slider. This is operated by means of a 'pull tab', so called because, logically enough, the wearer or user pulls it in one direction or the other. To close the zip, a wedge inside the slider pushes the hook of each tooth on one side into the hollow of each offset tooth on the other; to open it, the wedge forces them apart. To prevent the slider coming off the teeth at the other end, there is a 'top stop' on both sides of the zip. This basic design has changed little in the many years since it was first introduced, although nowadays, of course, zips – zippers – are available in a whole range of shapes, sizes and materials.