Hair Porosity: What It Is and How to Care for Yours

Short answer: Hair porosity describes how easily your hair takes in water and how long it holds on to it, which depends mostly on the state of the cuticle. Low-porosity hair resists water and lets products sit on top; high-porosity hair absorbs fast, dries fast and frizzes. Knowing yours helps you decide how rich your conditioning should be.

Quick facts

Porosity	Cuticle	In one line
Low	Tightly closed, flat	Slow to get wet, slow to dry, products sit on top
Medium	Mostly flat, slightly open	Takes in and holds water evenly, the easiest to manage
High	Raised, chipped or worn	Soaks up water fast, loses it fast, prone to frizz and tangles

What is hair porosity?

It is a measure of how readily water and products can move into and out of a hair strand. Each hair has an outer layer of overlapping scales called the cuticle. When the scales lie tight and flat, water has a hard time getting in, and once in, it stays. When they are lifted or worn away, water rushes in and leaves just as quickly. That difference shapes how your hair washes, dries, holds a style and responds to conditioner.

Porosity is not fixed along the whole strand. The hair nearest your scalp is newest and usually least porous. The ends have been washed, brushed, styled and exposed to sun for months or years, so they are often more porous than the roots. Many people have medium-porosity roots and high-porosity ends.

What causes high-porosity hair?

Mostly wear and processing, sometimes genetics. Bleaching and colouring open the cuticle by design. Frequent high heat, sun, chlorinated water, rough towelling and brushing knots out from the root all chip and lift it over time. Some hair is naturally more porous, and tightly curled hair can be more porous at the bends of each curl. Low porosity, by contrast, is usually natural and common in hair that has never been coloured or heat-styled much.

How do you test your hair's porosity?

Watch how your hair behaves on wash day; it tells you more than a glass of water. The popular float test, where you drop a strand into water and watch whether it sinks, is unreliable. Oils, product residue, the water's surface tension and tiny air bubbles all affect whether a hair floats, so the result says little about porosity.

Ask yourself these questions instead:

• Getting wet: does water bead and run off your hair in the shower, or soak in at once?
• Drying: does your hair take hours to air-dry, or is it dry surprisingly fast?
• Products: do conditioners and oils seem to sit on top and feel greasy, or vanish and leave hair thirsty soon after?
• Feel: is your hair smooth and slippery, or rough and quick to tangle?
• History: has it been lightened, coloured or heat-styled often?

Slow to wet, slow to dry and prone to product build-up points to low porosity. Fast to wet, fast to dry, rough and frizzy points to high porosity. Somewhere in between is medium.

How should you care for each porosity type?

Match the richness of your conditioning to how much water your hair can take in and hold.

Porosity	What helps	Go easy on
Low	Lighter conditioners, applying products to warm, damp hair, occasional clarifying wash	Heavy butters and thick layers of oil that sit on top
Medium	A regular conditioner, a mask every week or two, sensible heat	Over-processing that pushes it towards high porosity
High	Conditioner every wash, a weekly protein-rich mask, a leave-in on the lengths, low heat	Hot water, frequent heat styling, rough towelling

Is a keratin mask good for high-porosity hair?

Often, yes, because porous, processed lengths tend to respond well to a protein-rich, conditioning mask. Our Keratin Intensive Rescue Hair Mask combines hydrolysed keratin, wheat proteins and peptides, which help hair feel stronger and reduce the look of breakage and split ends, with shea butter and vitamin E, which condition dry lengths for softer, smoother, shinier-looking hair that detangles more easily.

Use it once or twice a week after shampooing, on towel-dried hair, from mid-lengths to ends. Leave it on for five to ten minutes, rinse thoroughly and use it in place of your conditioner. If your hair is low porosity, you may find a smaller amount is enough. It is not vegan, as it contains hydrolysed keratin, and it contains wheat proteins.

Where does a pre-wash oil fit?

Before shampoo, as a way to care for the scalp and keep dry lengths from feeling stripped. Many people with porous hair like to coat the lengths with a light oil before washing. Our Rosemary Hair & Scalp Strengthening Oil is designed for this: massage a few drops into the scalp and through the lengths, leave it for at least fifteen minutes, then shampoo thoroughly. It combines rosemary, almond and peppermint oils, and helps dry-looking hair feel softer and look smoother and glossier. Low-porosity hair needs only a few drops and a thorough shampoo afterwards. Almond oil is a nut oil, so skip it if you have a nut allergy, and keep the peppermint oil away from your eyes. Our rosemary oil guide explains the full ritual.

Can you change your hair's porosity?

Not in the lengths you already have, but you can stop it getting worse. A lifted, worn cuticle does not return to its original state. Good conditioning makes porous hair feel smoother and behave more evenly for the days between washes, and gentler habits stop the problem spreading further up the strand. The new hair coming through at the root has your natural porosity, and regular trims gradually remove the most porous ends.

Common mistakes

• Trusting the float test. It mostly measures surface tension and product residue.
• Assuming one label fits the whole head. Roots and ends often behave differently.
• Piling rich butters on low-porosity hair. They sit on top and leave it limp and greasy.
• Using only protein on high-porosity hair. It needs moisture-focused conditioning too.
• Ignoring heat. Frequent high heat can turn medium porosity into high porosity over time.

What porosity care won't do

Knowing your porosity helps you choose textures and amounts. It does not change your hair type or texture, and no product rebuilds a worn cuticle. Care makes hair feel softer and look smoother and shinier, and that effect is renewed with every wash and every mask, not stored for good.

Frequently asked questions

Is the float test accurate?

Not really. Whether a strand floats depends on oils, residue, surface tension and air bubbles as much as porosity. Watching how your hair wets, dries and takes products is more reliable.

Can hair porosity change?

Yes, usually towards higher porosity. Bleaching, colouring, heat and sun all lift the cuticle over time. The change stays in those lengths until they are trimmed away.

Does high-porosity hair need protein?

It often benefits from a protein-rich mask once or twice a week, alongside regular moisturising conditioner. If hair starts to feel stiff, ease off the protein and focus on conditioning.

Is low-porosity hair a good thing?

It is neither good nor bad. It tends to be smooth and shiny but slow to absorb products. Lighter textures, warm damp hair and the occasional clarifying wash make it easier to care for.

Does oil help low-porosity hair?

A little light oil can, especially as a pre-wash step. Heavy oils left in tend to sit on the surface, so use only a few drops and shampoo thoroughly.

Find the rest of your wash-day routine in our hair care collection.

Last reviewed: October 2026.