How Does Velcro Stick?

Step 1 of 5

The two sides are not the same.

One strip is covered in stiff plastic hooks; the other in soft fluffy loops. Two hook sides or two loop sides will not hold at all.

Step 2 of 5

Pressing them together catches thousands.

Each hook only holds a tiny amount. But a small patch has thousands of them, and together they hold far more than their own weight.

Step 3 of 5

Pulling straight apart is hard.

Every hook must be bent open at once, so the load is shared across all of them. That is why a straight pull feels so strong.

Step 4 of 5

Peeling from a corner is easy.

Peeling releases a few hooks at a time in a line. The same fastening feels weak because you never fight more than a handful at once.

Step 5 of 5

It was copied from a plant.

A Swiss engineer looked at burrs stuck to his dog under a microscope and found tiny hooks. Velcro is a direct imitation.

Copying a design from nature like this is called biomimicry — the same idea behind shark-skin swimsuits.