Frizz and humidity: the actual mechanism

Hair is hygroscopic: it absorbs water from the air around it. As it does, water molecules form hydrogen bonds within the keratin structure, and the fibre swells.

Two consequences. Swelling pushes the cuticle scales outward, so the surface roughens and individual strands stop lying against each other neatly. And because the hydrogen bonds holding your hair's current shape are being rearranged by that water, hair reverts toward its natural pattern. A straightened style collapses; waves become undefined.

Frizz is therefore worst where there is the biggest gap between your natural texture and the style you have imposed, which is why the same weather ruins one person's blow-dry and merely puffs up another's curls.

An intact cuticle lying flat is a reasonable barrier, slowing how fast atmospheric water gets in. A raised, chipped or gapped cuticle is not. High porosity hair absorbs humidity quickly and swells more, so it frizzes faster and more dramatically.

This is the link between damage and frizz, and it is why reducing heat and chemical processing does more for monsoon hair than any anti-frizz product.

Create a barrier

Anything that slows water reaching the fibre reduces swelling. A light oil on the mid-lengths and ends, a silicone-containing serum, or a leave-in cream all work on this principle. Apply to damp hair, before drying, rather than to dry frizz after the fact.

Reduce the moisture gradient

Hair that is already properly moisturised absorbs less from the air, because the gradient driving absorption is smaller. Well-conditioned hair frizzes less than dry hair in the same weather.

Be careful with humectants

Glycerin and similar humectants attract water. In moderate conditions that is useful. In very humid air they pull in more moisture and can increase frizz. If your leave-in makes things worse in monsoon, check the ingredient list for glycerin high up.

Stop fighting the texture

Working with your natural pattern rather than against it is the most reliable monsoon strategy. A style that does not depend on heat holding hair in an unnatural shape cannot collapse.

• Dry hair properly. Tying up damp hair in humid weather leaves it damp for hours and leaves the scalp uncomfortable.
• Detangle gently and expect more tangles, since a swollen, raised cuticle catches on itself.
• Use a wide-tooth comb rather than a brush.
• Rinse after being caught in city rain rather than letting it dry in.
• Consider a loose braid or bun for travel rather than leaving hair loose to abrade against clothing.
• Do not skip washing because the air is humid. That does not help either hair or scalp.

• Brushing frizz down. Friction on a raised cuticle makes it worse.
• Adding more product to dry frizz. The barrier needs to be there before the hair dries.
• More heat to force the style. It works for an hour and costs cuticle.
• Expecting a product to overcome a large gap between natural texture and imposed style in genuinely humid weather.