Why Humidity Brings Out Curls in Your Hair and Makes Straight Hair Wavy: Understanding Hair Bonds

Many people find that humidity brings out the curls in the hair and makes straight hair more wavy.

The reason lies in the interaction between water and molecules in the hair.

Hair is made up of long spiral-shaped molecules called keratin, which lie in bundles somewhat in the same way as the cord parts – or the seals – in a rope. The keratin strands are held together by chemical bonds. And it is these bonds that determine how the hair behaves – whether it is curly, frizzy, wavy or smooth.

Weak bonds curl the hair

Permanently curly or frizzy hair is due to so-called disulphide bonds, which bind two keratin strands together via sulfur atoms.