The full name of the Japanese zipper manufacturer Yoshida Kōgyō Kabushikigaisha would obviously be too long to put on the little zipper slider – that’s why it was shortened to the now very well-known abbreviation YKK. As the world’s largest developer and manufacturer, YKK produces zip fasteners on in-house designed machines - from the raw material to the finished product – and that in the highest of quality.
Below is a small overview of the different types of zip fasteners that we have in our assortment including their basic functions and how to go about determining their lengths.
Divisible Zipper: A divisible zipper opens up completely and is therefore used on, for example, jackets. The length is determined by measuring from the bottom of the retainer box, in which one side (tape) of the zipper is inserted, to the upper end of the slider (when the zipper is closed). This means that what is measured is the length of the zipper chain and not the length of the zipper tape (fabric). Divisible zip fasteners also come as so-called 2-way zippers that can be opened from the bottom or the top because there are two sliders.
Non-separable Zipper: A non-separable zip fastener is closed on the bottom end by a bottom stop which prevents it from separating at that point. This kind of zipper is used with pants, dresses, bags and many more such articles. Its length is determined by measuring from the bottom of the bottom stop on the zipper chain to the upper end of the slider when the zipper is closed. Zippers that are too long can be shortened by simply using a sewing machine to sew thread across the chain rows a number of times in order to close the chain off to the required degree – the rest is then just cut off.
Another differentiating feature involves the type of teeth a zipper has, including the type of material they are made from:
Plastic spiral: In the case of spiral zip fasteners, a fine polyester spiral is woven into both zipper tapes, one on each side. The spiral and the slider are the same colour as the tape. Zippers with spirals are best used on lighter materials where not much stress will be put on them.
Plastic teeth: Zip fasteners with plastic teeth are produced by an injection moulding process in which molten plastic is injected into the zipper tape. The teeth and the slider are the same colour as the tape. Zip fasteners with robust, course teeth are suitable for use with heavier materials and leather and where they will be exposed to higher amounts of stress as, for instance, in motorcycle and ski clothing.
Metal teeth: Metal teeth made of brass are compressed onto the zipper tape like little clamps. Metal zip fasteners are used on more substantial materials like, for example, jeans (buttons are of course cooler!).
Automatic slider: The automatic slider will open and close the zip fastener only when you pull on the tab (puller) – the zipper will not open on its own because it is locked in place. The puller (tab) often has an eyelet through which a string or small tape is threaded to serve as an extension of the puller and makes it that much easier to activate.