The Science of Textured Hair

“Hair is truly one of the marvels of Blackness.”

— Charlotte Mensah, Good Hair

The scalp

Where it all begins. The scalp itself is multiple layers of skin, starting with the subcutaneous at the bottom where all the fat and blood vessels live, then the dermis with its collagen to strengthen and support the skin. And right at the top sits the epidermis, with the sole function of protecting those layers underneath. Hair grows from the dermis layer. “It’s important to hydrate the body from within,” advises celebrity hair stylist and founder of Hair Lounge salon, Charlotte Mensah, in her book Good Hair. “If you’re dehydrated, your body will supply little moisture to the upper layers of your skin, and you’ll have to rely on external moisturising products to hydrate the scalp.” 

The hair follicle

Nestled in the dermis lies the follicle, surrounded by blood vessels that bring nutrients to it, and things with long Latin names like the arrector pili muscle (that makes hair stand up on end in the cold), and the sebaceous gland. “These can be found everywhere except our palms and soles of the feet,” writes Charlotte. “They produce sebum, our hair and skin’s natural oil that conditions them and acts as a barrier to prevent internal moisture loss – a healthy scalp produces an ounce of sebum every 100 days.” 

We got deep into the hair growth cycle in another article, but we’ll add here that it all starts and ends right in the follicle. As hair is growing in the anagen phase, its base, or bulb, stays locked down into the follicle, and gradually detaches itself in the shedding phase.

And as hair grows, it pushes out of the scalp and enters a brave new world (cute!) where we can do whatever we want with it. The deciding factor of whether this little baby hair will be curly or straight? The follicle hole it grows through. The more circular the shape, the straighter the hair. When it comes to understanding the follicular shape of curly and Afro hair, imagine the act of grabbing a pair of scissors and using the blade edge and your thumb to curl a plastic ribbon. The effect is pretty much the same – the follicle hole’s flatness puts the hair at an angle as it grows, leading to the coiled shape. 

The hair shaft

This is all the hair we see from the scalp onwards, made up of dead skin cells that have been compressed and packed into a protein named keratin – just like our nails. The two couldn’t look more different, but need to be taken care of in nearly the same way: not too many chemicals and extensions, lots of hydration, conditioning with oils, and stimulated blood flow at the base. 

But the follicle isn’t all when it comes to defining the hair texture. “Natural hair textures have an uneven build-up of keratin along the hair shaft,” writes Charlotte. “The hair bends where the keratin layers are heaviest and thins where they are less. This gives movement along the hair shaft.”

The shaft itself has three internal and external layers, which can be explained the best in our glossary: the empty-ish medulla at the centre, the cortex which determines the hair colour and strength, and the cuticle on the outside. The cuticle gets a lot of attention for deciding the shininess and softness of hair; it’s what silicones, conditioners and oils wrap around to seal, and what deep treatments and some oils (especially hot ones) try to penetrate to get to the cortex. With rough handling, heat-styling and chemical treatments, the sheaths of the cuticle become worn away, giving a dull look to the hair overall. 

“The cortex, however, is the most significant layer of the hair as it makes the bulk of it,” writes Charlotte. And here’s where it gets really technical. “Afro and curly hair types have both a para and ortho cortex, meaning the structure of one side of a single hair differs from the other.” The ortho’s less dense and has less sulphur than the para, and also sits on the outside of the wave, causing different textures along one strand of hair. Read that back one more time and trust us, it’ll sink in.

Now that you have all the details you could ever need, head over to our hair type versus hair texture page, and book in with one of our hair gurus to get even more personalised in your newfound hair knowledge.