By Heather Brown

MINNEAPOLIS (WCCO) — In sticky summer weather, the most well-tamed locks can become unruly.

Kay from Farmington asked: Why does the humidity make your hair frizzy?

For this answer, WCCO talked with Irina Makarevitch, a professor of chemistry at Hamline University, and Libby O’Neil, a colorist at Juut Salon.

They say hair is built from proteins called keratin and how those proteins bind together give hair its shape and strength.

One of the bonds they make is very strong. It’s called the disulfide bond and determines if a person’s hair is naturally curly or straight.

But that’s not the bond affected by humidity.

There’s another kind – the hydrogen bond – that gives hair a frizz when it’s humid outside.

That hydrogen bond isn’t as strong as the disulfide and breaks when a person’s hair gets wet. Those bonds reform with heat, which is why someone can style their hair with a blow dryer.

When it’s humid outside, that means there’s more water in the air.

Given water is partly made up of hydrogen, the keratin molecules in a person’s hair form bonds with the water molecules in the air. And, because there is more hydrogen in the hair when it’s humid, it means there are more hydrogen bonds in the strands of hair.

All of those bonds mean the hair starts to double back on itself and coil, which is what creates the frizz.

Both Makarevitch and O’Neil say moisturizing hair will help fight frizz. When the hair is dry, it soaks up the water in the air, which makes more of the hydrogen bonds that make hair curl.

If hair is already moisturized, it doesn’t need to build those connectors.

Heather Brown


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