How does Velcro work?

How it works: 15-second answer

Velcro is a hook-and-loop fastener made of two parts: loops and hooks. When pressed together, the hooks latch onto the loops, creating a secure bond. Pulling them apart requires force because the hooks resist separation while the loops stretch.

It’s interesting how Velcro came into existence. Well, velcro was invented by Georges de Mestral when he was on a hike with his dog in the Swiss Alps in the 1940s. The idea came to him after he noticed plant seeds sticking to his dog’s fur. He observed the seeds under a microscope and saw tiny hooks. Thus, the velcro was born.

How does a Velcro work?

All of us have used Velcro at some point in our lives. It is a hook-and-loop fastener consisting of two components: loops and hooks. The next time you use Velcro, take a moment to touch it. You’ll notice that the soft side contains numerous loops made of elastic material as shown in Figure 1 (Top). Meanwhile, the rough side is covered with tiny hooks like fish hooks as shown in Figure 1 (Bottom).

The loops and hooks are elastic and typically made from nylon or polyester.

Figure 1: The two parts of the velcro are hooks (bottom) similar to fish hooks and loops (top).

When the two parts are joined, the hooks catch on to the loops, as shown in Figure 2.

Figure 2: The loops get caught by the hooks, thereby binding both the parts together.

The hooks latch onto the loops, making Velcro difficult to separate and allowing it to function as a fastener. When you pull the two sides apart, the hooks naturally bend, resisting separation, while the loops stretch until they finally slip free, as shown in Figures 3 and 4. The hooks work to hold onto the loops, while the loops struggle to break away.

Figure 3: Hooks trying to not leave the loops, while loops stretching and getting away - when pulled apart. Source: The MacroManiac

You might wonder if the loops would tear when pulled away from the hooks. However, they don’t. Because the loops are elastic, they can stretch and return to their original shape, allowing Velcro to be used multiple times.

Figure 4: Loops getting stretched to leave the hooks upon pulling them apart

This is how a Velcro works!