Humectants

Humectants are one of those ingredients that everyone talks about but nobody fully understands — and honestly, the science is still catching up. The idea is that they help your hair absorb and hold onto moisture, though the evidence is more anecdotal than clinical. Still, the curly community swears by them (with some important caveats about weather).

Do Humectants Cause Frizz?

Here's the theory: humectants pull moisture from the surrounding air. On a gorgeous mild day, that's amazing. But in really dry weather, there's barely any atmospheric moisture to grab — so some believe they could draw water out of your hair instead. What science has shown is that in low-humidity conditions, humectants can become brittle and feel rough or dry to the touch.

In humid weather, the opposite concern kicks in: humectants might pull in too much moisture, swelling the hair shaft and causing frizz. Again, this is mostly theoretical, but enough people have experienced it that it's worth knowing about.

Breaking Down the Types

Not all humectants behave the same way, so we organise them by how they interact with your curls:

Simple Humectants: Your classic humectants like glycerin. They do a brilliant job most days, but in very dry conditions they can turn brittle and actually contribute to frizz and friction.

Film-Forming Humectants: More complex molecules like flax seed extract that have an intricate structure with plenty of space to store water. They're less affected by dry air and form a protective film over your hair that can actively fight frizz. Think of them as the overachievers of the humectant world.

Proteins: Surprise — proteins are technically humectants! Most behave like the complex type, but they get their own category because of the whole "protein overload" conversation. (The science on that is still pretty thin, for what it's worth.)

Amino Acids: The building blocks of proteins. In hair care, they're used to help repair and strengthen damaged strands by rebuilding protein structures from the ground up.

Should You Avoid Simple Humectants When the Weather's Extreme?

This is where formulation really matters. Plenty of holy-grail humid-weather products contain glycerin — but they also pack in film-forming ingredients like silk protein and panthenol, plus emollients like castor oil. Those supporting ingredients keep the glycerin from misbehaving. It's like having humectants for your humectants.

Most well-formulated curl products already strike this balance beautifully. But if you're using simpler, minimal-ingredient products, you might want to swap them out on extreme weather days.