In short
- Porosity = how easily the cuticle absorbs and releases moisture.
- The water-glass float test is unreliable — technique and product residue skew results.
- High porosity hair benefits from protein + oil layering; low porosity benefits from heat and lightweight leave-ins.
- Damage raises porosity permanently until the damaged section grows out.
Porosity is one of the most-discussed hair concepts on social media and one of the most poorly tested. It matters — but not always in the way the tests suggest.
What porosity actually is
The hair cuticle is made of overlapping scales. Low porosity means tight, flat scales — water and product roll off. High porosity means lifted scales — water absorbs and evaporates fast. Damage (bleach, heat, mechanical) permanently raises porosity in that section.
The reliable tests
Skip the water-glass float test. Better: after washing, how fast does hair air-dry? Under 30 minutes = high porosity; over 2 hours = low. And: after applying leave-in, does it absorb immediately (high) or sit on the surface (low)?
Routines by porosity
- Low porosity — lightweight leave-ins, gentle heat to open cuticle for treatments, clarify weekly.
- Medium — most standard routines work.
- High — layer proteins (weekly) with oils (daily), avoid over-cleansing, deep condition every wash.
Porosity is a routine map, not an identity.
Frequently asked
Common questions
Can I lower my porosity?+
Not the porosity of already-grown hair. New growth reflects your baseline. Bond-repair treatments temporarily smooth the cuticle.
Is high porosity bad?+
No — just different. It means your hair needs a more layered routine but takes colour and treatments beautifully.
How does colour affect porosity?+
Every colour service raises porosity slightly; bleach dramatically. Bond-repair and glossing offset this.
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