What are Hook & Loop Fasteners Made of?

Hook and loop fasteners consist of two distinct pieces. The rough, scratchy side is the hook because it is covered with several tiny hooks per square inch. Likewise, the soft, fuzzy side is the loop because it is covered with many small loops. The hooks engage the loops when the two sides are pressed together. This creates a bond that is exceptionally strong and allows for repeated use that lasts for thousands of cycles.

What Is Hook And Loop Made Of?

Most hook and loop fasteners are made out of nylon, but there are several different monofilament materials such as polyester and polypropylene that are also used. Monofilament is a single continuous strand of synthetic fiber (as opposed to woven fibers). Monofilament is 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 low resistance to ultraviolet light. Polyester, on the other hand, is resistant to ultraviolet light but has a lower tolerance to high temperatures. Nylon and polyester are also hydrophobic materials, meaning they do not easily absorb water.

Treated Hook And Loop

Some hook and loop is treated, typically by spraying the material, to add a layer of protection or function. This can include keeping the material from fraying when cut, to more specific purposes like allowing the material to burn slower to meet fire retardant (FR) standards. Another specific example is spraying the hook and loop with silver to give it electric conductivity for use in static or radio environments.

How Are Hook And Loop Fasteners Made?

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 weaving nylon under hot, infrared light. The nylon monofilament used in the making of the hooks keeps its shape and is very resilient. After weaving, the loops of nylon get trimmed off to create 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.

Hook and loop 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. Browse our VELCRO® Brand hook and loop here.