What are Hook & Loop Fasteners Made of?

Hook and loop fasteners consist of two distinct pieces. There is the rough side, known as hook because it is covered with several tiny hooks per square inch, and there is the soft side, known as loop because it is covered with many small loops. When the two sides are pressed together, the hooks engage the loops. This creates a bond that is exceptionally strong and allows for repeated use without the products wearing out.

Hook and loop fasteners are made out of several different monofilament materials such as nylon, polyester and polypropylene. Monofilament is a single, continuous strand of synthetic fiber (as opposed to woven fibers) used in fishing line, tennis racquets and medical sutures. Nylon is durable, tough and light in weight. It can withstand high temperature variations but has a very low resistance to ultraviolet light and water. Polyester, on the other hand, is resistant to water and ultraviolet light but has a low tolerance when it comes to high temperatures. Polypropylene is resistant to water and ultraviolet light. It is also easily heat-sealed.

Silver coated hook and loop fasteners being peeled apart. Silver coated hook and loop fasteners being peeled apart.

The simple concept of the hook and loop design took a while to perfect before evolving into the technology of today. The hook side is created by sewing nylon under hot, infrared light. The nylon thread used in the making of the hooks keeps its shape and is very resilient. After weaving, the nylon loops get trimmed off, creating many hooks that then match up with the loops in the soft side. These hooks need to be cut in just the right place so that they can adhere to the loop side and be fastened and unfastened many times.

roll-hook 88 macro Close-up of cut monofilament, creating the hook.

Hook and loop material fasteners are available in sew-on and peel and stick versions as well as many specialized varieties of hooks and loops. This very unique and convenient fastening system is used in a broad range of industries around the world, including aerospace, automotive, medical and military sectors.

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