You bought the leave-in everyone raves about and your hair went stiff and coated. Your friend used it and her curls popped. Neither of you did anything wrong. Your hair does not absorb water the same way.
What porosity is
The outer layer of each hair, the cuticle, is made of overlapping scales. How tightly they lie determines how easily moisture gets in and gets out.
- Low porosity: scales lie flat and tight. Water beads on the hair, products sit on top, the hair takes ages to get wet and ages to dry. Very common on healthy, unprocessed coily hair.
- High porosity: scales are lifted or damaged. Water rushes in and rushes out. Hair gets wet instantly, dries fast, frizzes, tangles and breaks. Often the result of heat, colour, relaxers or rough handling, though some people are born with it.
- Medium porosity: the easy one. Most products work.
Find yours in two minutes
Forget the floating-strand test: it is unreliable. Instead, watch your hair on wash day. Does water take a while to soak in, and does your hair stay damp for hours? Low porosity. Does it soak instantly and dry within the hour, feeling rough? High porosity. Do products sit as a white film on your strands? Low. Does moisture never seem to last past a day? High.
Low porosity: open the door
- Warm water and steam before applying products; a warm towel or a hooded dryer over your deep conditioner.
- Light, water-based products. Heavy butters and thick creams just sit on top.
- Clarify regularly: build-up is your enemy.
- Apply products on soaking wet hair, in small amounts.
High porosity: close the door
- Protein treatments to fill the gaps in the cuticle, alternated with moisture.
- Richer creams and butters to seal, applied after a leave-in.
- Cool water for the final rinse and acidic rinses to flatten the cuticle.
- Less heat, less manipulation, satin at night, and trim damaged ends.
Why it matters for your scalp too
Low porosity hair often comes with heavy products that end up on the scalp and cause build-up and flaking. High porosity hair breaks and is mistaken for hair loss. Knowing your porosity fixes half of the routine problems we see in consultation.
See our trichology service or book a diagnosis on WhatsApp to get products matched to your hair, not to a trend.
