Hair porosity explained

What it is

Porosity is how easily hair absorbs and holds water.

How it works

The cuticle is overlapping scales. Low porosity: tightly closed. High porosity: raised or damaged, often from chemicals or heat.

Why it matters on darker skin

Coily hair is prone to high porosity at the ends from manipulation.

Causes and triggers

Genetics, heat, chemical treatment, sun.

What helps — and why it works

Low: warmth with conditioners, lighter products: helps product penetrate. Expected timeline: weeks. High: deep conditioning and sealing: fills and seals gaps. Expected timeline: weeks.

More detail

Porosity describes how the cuticle — the outer layer of overlapping cells — controls water moving in and out of the hair shaft. In low porosity hair the cuticle lies flat and tight, so water beads on the surface, hair takes a long time to get wet and dry, and heavy products sit on top and build up. Lighter, water-based leave-ins, applying products to damp hair, and gentle warmth (a warm towel or hooded cap) during conditioning help. High porosity hair has a lifted or damaged cuticle, often from bleach, relaxers, heat or sun; it absorbs water quickly but loses it quickly too, so it feels dry and frizzy soon after washing. Protein treatments can temporarily fill gaps, and richer creams and oils seal moisture in. The float test is unreliable because product residue and oils change how a strand behaves, so our questionnaire uses several signs together. Porosity can differ between roots and ends.

What to avoid and why

Avoid relying only on the float test.

Common mistakes

• Heavy products on low-porosity hair.

Handling textured hair gently

Coily and curly hair is naturally the most fragile hair type because each bend in the strand is a weak point and natural oils travel down it slowly. That makes handling — how often and how firmly hair is combed, styled and pulled — as important as which products you buy. Detangle only when hair is wet and coated in conditioner, working in sections from the ends towards the roots with fingers or a wide-tooth comb. Keep heat to the lowest effective setting and always use a heat protectant. Sleep on satin or silk, or wear a satin bonnet, to reduce friction. Between wash days, a water-based leave-in followed by a light oil or cream helps hold moisture. Give the scalp attention too: it is skin, and needs regular cleansing, especially under wigs, weaves and braids, to prevent build-up, itch and infection. Any style that hurts, causes bumps or leaves the scalp tender is too tight and should be loosened. Hair grows about one centimetre a month, so changes in care take two to three months to show in length and thickness.

Scalp health and product choice

Choose a shampoo that suits the scalp and a conditioner that suits the lengths: the scalp may need cleansing or a medicated shampoo while the ends need moisture. Fragrance, essential oils and heavy waxes can irritate a sensitive scalp or cause build-up, and heavy oils on the scalp may worsen dandruff. Look for a clear ingredient list and a NAFDAC number, and patch-test new dyes and relaxers 48 hours before every use. Products that promise dramatic growth are usually untested; the treatments with the best evidence for pattern hair loss are medicines such as minoxidil, which should be started only after speaking to a pharmacist or doctor. Signs that you need medical advice rather than a new product include patches of hair loss, scarring or shiny skin, pain, pus, or shedding that continues for more than six months.

Questions to ask your doctor or pharmacist

Useful questions include: What do you think is causing this? Is it likely to come back, and how can I prevent it? Which products should I stop? How long before I should expect improvement, and when should I come back if it isn't better? Are there side effects to watch for? Is this treatment safe if I am pregnant, breastfeeding or for my child? Writing your questions down, bringing your products (or photos of their labels) and taking dated photos of the problem make an appointment much more useful.