A separating zipper is a zipper designed to separate completely, allowing two parts of a garment, sleeping bag, or pack to come completely apart, rather than being bound at one end by the base of the zipper. It is common on jackets, sleeping bags, and garments designed to convert, such as pants that turn into shorts. This type of zipper is extremely versatile, making it a good choice for many applications.
A separating zipper is designed much like a conventional zipper, with two strips of sturdy fabric studded with small metal or plastic teeth that can be joined together to make a seal. Zippers use a manually operated slider to open and close – depending upon the direction of movement, the y-shaped channel inside the slider either separates or joins the individual zipper teeth. Zippers are usually integral to the garments they appear in, and when the zipper becomes damaged or broken, the garment is often unusable until the zipper is repaired or replaced.
Zippers are used in a variety of applications. Sometimes a zipper is purely ornamental, and sometimes it is designed to allow access to a pocket or pack for secure storage. Zippers are also used like buttons, to allow the passage of larger objects, like waists and legs, through garments that can then be closed. Many jackets and sweatshirts make use of the separating zipper, as do some athletic pants, rather than the open-ended type, which is sealed at one end to prevent the slider from coming off.
In the case of a separating zipper, the base of the zipper is open, allowing the slider to completely disengage from the other side of the fabric. A small tab on the other side of the zipper can be reinserted into the slide to rejoin the two pieces. Two textiles with separating zippers can also be joined together to make, for example, a double-sized sleeping bag. This allows the user to separate and potentially reconfigure garments, sleeping bags, and backpacks. Many backpacking companies, for example, sell backpacks with zip-off daypacks that use a zipper that separates.
Installing of a separating zipper in a garment is slightly different than installing a conventional zipper, primarily because the sewer is presumably making use of this zipper's unique qualities. Rather than using the zipper to make a small opening in a skirt or jacket, for example, the creator would leave the areas above and below the separating zipper open, so that the two parts of the garment being joined could be pulled fully apart when upzipped. The separating zipper first appeared about fifty years after the initial invention of the zipper, and it greatly expanded the range of uses in which zippers appeared, making the simple device a common household name.