Hair Porosity Explained: How to Know If You Have Low, Medium or High Porosity Hair
September 28, 2026You may already know whether your hair is straight, wavy or curly. But another concept can help explain why one product makes your hair beautifully soft while another makes it feel coated: porosity. Hair porosity describes how readily the hair fibre takes in and releases moisture.
What is low-porosity hair?
Low-porosity hair tends to have a cuticle structure that makes it harder for water and products to penetrate. It may take longer to become fully wet and can feel weighed down by heavy layers. Lightweight products and sensible cleansing can often work better than repeatedly adding rich oils.
What is high-porosity hair?
High-porosity hair tends to take in water and products readily but may also lose moisture more quickly. It can feel dry, rough, frizzy or prone to tangling, particularly after heat, colouring or chemical processing.
What about medium porosity?
Medium or normal-porosity hair sits somewhere between the two. It often behaves predictably with a straightforward routine, but porosity can change as hair is damaged or chemically treated.
Can you do the water-glass test?
You may have seen the advice to put a strand of hair in a glass of water. Treat this as a fun observation rather than a definitive scientific diagnosis. Product residue, surface oils, strand thickness and hair condition can affect the result. Your hair's day-to-day behaviour is usually more useful.
Build your routine around behaviour
If products consistently sit on your hair, buildup quickly and heavy oils flatten it, you may prefer lighter layers. If your hair loses moisture quickly, frizzes and feels rough, consistent conditioning and protection from heat and friction may matter more. JC's existing frizz article explains how humidity interacts with hair structure.
The takeaway
Porosity is a useful framework, not a permanent identity. Hair can become more porous with damage and chemical processing. Use the concept to guide your choices, then let your hair's actual behaviour make the final decision.
Recommended internal links
frizz in humid weather article | JC hair care library
FAQs
Q: Is the hair porosity water test accurate?
A: It is not a definitive scientific test. Use your hair's behaviour as the more useful guide.
Q: Can low-porosity hair use oil?
A: Yes, but lighter amounts and lighter textures may feel more comfortable and reduce buildup.
Q: Does bleaching change hair porosity?
A: Chemical processing can damage the cuticle and change how readily hair absorbs and loses moisture.
Q: Does hair porosity stay the same forever?
A: No. Damage, chemical processing, heat and environmental exposure can change hair behaviour over time.
