What Is Hair Porosity? A Parent’s Guide to Understanding Natural Hair
Suitable for parents of children ages 7–15
Every parent doing wash day has asked some version of the same question: why does my child’s hair soak up water and dry out in minutes, while a friend’s child’s hair stays damp for hours? The answer usually comes down to one thing — hair porosity.
What Is Hair Porosity?
Hair porosity describes how easily your hair’s outer layer, called the cuticle, allows moisture in and out. Think of the cuticle like tiny shingles on a roof. When those shingles lie flat and tight, water has a harder time getting in or out — that’s low porosity. When the shingles are lifted and a little more open, moisture moves in and out quickly — that’s high porosity. Most children’s hair falls somewhere in the middle, described as medium porosity.
A Simple At-Home Porosity Test
You don’t need a lab to get a good sense of your child’s hair porosity. Try the float test together as a wash-day activity:
- Fill a clear glass with room-temperature water.
- Take one clean, product-free strand of hair (from a brush or comb is fine).
- Drop it into the water and watch what happens over 2–4 minutes.
Hair that floats near the top is usually low porosity. Hair that sinks slowly and sits in the middle is usually medium porosity. Hair that sinks quickly to the bottom is usually high porosity.
Why Porosity Matters on Wash Day
Once you know your child’s porosity type, wash day gets a lot less guesswork:
- Low porosity hair benefits from lighter products, warm water to help the cuticle open, and a little patience — heavy products tend to sit on top rather than absorb.
- Medium porosity hair is generally the easiest to manage and responds well to a balanced routine.
- High porosity hair needs richer, moisture-sealing products and protective styles, since moisture escapes just as easily as it enters.
This is exactly the kind of hands-on hair science we cover in Little Crowns, Big Confidence — helping kids understand their own hair well enough to feel proud of it.
Turn It Into a Wash Day Habit
Once you know your child’s porosity, track products and results with our free Wash Day Chart — a simple way to build a consistent, confidence-building routine together.
For classrooms and libraries introducing hair science as part of an SEL lesson, our Little Crowns Confidence Programme includes a full porosity lesson plan for grades 3–8.
This article is for educational purposes. For personal hair health advice, consult a qualified trichologist or dermatologist.
Frequently Asked Questions
What is hair porosity?
Hair porosity is how well your hair’s outer layer (the cuticle) absorbs and holds onto moisture. It’s usually described as low, medium, or high porosity.
How can I find out my child’s hair porosity at home?
A simple way is the float test: drop a clean strand of hair in a glass of water. Hair that floats is usually low porosity; hair that sinks quickly is usually high porosity.
Does hair porosity change over time?
Yes. Porosity can shift due to heat styling, chemical treatments, weather, and overall hair health, so it’s worth checking again if your child’s hair routine changes.
Why does porosity matter for wash day?
Knowing your child’s porosity helps you choose the right products and timing — low porosity hair needs lighter products and more time for moisture to absorb, while high porosity hair needs richer products to seal moisture in.
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PharmD, MSc, Trichologist
Dr. Kaspa is a Clinical Pharmacist and Cosmetic Formulation Scientist who founded Afro Luxe Braiding Bar and wrote Little Crowns, Big Confidence to help children build a healthy relationship with their natural hair. Read more about Dr. Kaspa →
Last reviewed by Dr. Bridget Kaspa, PharmD — July 2026