Hair Porosity: The One Thing That Determines Whether Your Hair Products Actually Work
You could be using the best shampoo in the world incorrectly — because you don't know your hair's porosity. Here's what it is, how to find yours, and what to do with that knowledge.
You've tried every shampoo. You've followed every tutorial. You've invested in good products. And your hair still behaves unpredictably — sometimes responding brilliantly to a product, sometimes refusing to absorb anything at all. Sometimes frizzy despite conditioning. Sometimes greasy despite washing.
The most likely explanation has nothing to do with which products you're using. It has to do with a single structural property of your hair that determines how every product interacts with your hair shaft: porosity.
Understanding your hair's porosity changes everything about how you shop for, apply, and think about hair care. It is the missing piece that makes sense of almost every otherwise inexplicable hair behaviour.
"Hair porosity is not a trend or a hair typing gimmick. It is basic structural biology — and once you understand it, you'll never buy a hair product the same way again."
What Is Hair Porosity?
Porosity refers to your hair's ability to absorb and retain moisture. Specifically, it describes the state of the hair cuticle — the outermost layer of the hair shaft, made up of overlapping scale-like cells — and how tightly or loosely those cuticle scales lie against the hair shaft.
Think of the cuticle scales like roof tiles. When the tiles are tightly overlapping and flat, water and products struggle to get in — but what's already inside (natural oils, moisture, pigment) also struggles to get out. When the tiles are lifted or damaged — gaps between them — water and products enter easily, but also exit just as easily.
There are three porosity categories, and your hair falls into one of them:
Low Porosity Hair: The Locked-Down Cuticle
Low porosity hair has a tightly packed cuticle with minimal space between scales. This is often genetic — associated with naturally fine or straight hair — but can also result from virgin (unchemically treated) hair in good condition.
What this means practically:
• Products sit on the surface rather than absorbing — you may notice products beading or rolling off rather than soaking in
• Hair takes a long time to get fully wet and a long time to dry
• Build-up from heavy conditioners, oils, and styling products is common — because products can't penetrate, they accumulate on the surface
• Hair resists chemical treatments — perms, colour, and relaxers take longer to process and may require higher processing times
• Once moisture is inside the shaft, it stays there — low porosity hair often has good natural shine
What works for low porosity hair:
• Heat during deep conditioning — warmth temporarily lifts cuticle scales, allowing products to penetrate
• Lightweight, water-based products — heavy butters and thick oils sit on the surface and create build-up
• Clarifying washes periodically — to remove the surface build-up that inevitably accumulates
• Protein-free formulas — low porosity hair generally doesn't need protein treatments and can become stiff and brittle with protein overload
High Porosity Hair: The Open Cuticle
High porosity hair has a lifted, damaged, or naturally wide-spaced cuticle. This can be structural (some hair types, particularly coarser or curlier hair textures, have naturally higher porosity) or damage-induced (from chemical treatments, heat styling, UV exposure, or mechanical damage from brushing and friction).
What this means practically:
• Hair absorbs water very quickly — gets wet fast in the shower, but also absorbs humidity from the air, causing frizz
• Products absorb readily — which sounds positive, but products also rinse out quickly, reducing their lasting effect
• Hair dries faster than low porosity hair — because moisture escapes through the gaps in the cuticle as easily as it entered
• Hair feels rough, tangled, or coarse — because lifted cuticle scales create friction between hair strands
• Colour fades quickly in colour-treated hair — the pigment molecules escape through the open cuticle
What works for high porosity hair:
• Protein treatments — help fill the gaps in the damaged cuticle temporarily, restoring smoothness and reducing porosity
• Heavy creams and butters (on ends) — provide the occlusive layer that seals moisture into a cuticle that can't hold it on its own
• Acidic rinses — vinegar rinses or citric acid rinses help close the cuticle temporarily
• Layering products — apply lighter, water-based products first, then seal with heavier creams or oils
• Avoiding heat styling where possible — heat further lifts already-compromised cuticle
Medium (Normal) Porosity Hair: The Balance Point
Medium porosity hair has a cuticle that is neither tightly sealed nor significantly raised. It absorbs products at a moderate rate, retains moisture reasonably well, and is generally the most versatile hair type in terms of product compatibility. Most hair care products are implicitly formulated for this porosity level.
Medium porosity hair tends to:
• Respond well to a wide range of products
• Hold styles and colour reasonably well
• Not require extreme adjustments to standard hair care routines
• Gradually increase in porosity with age, heat use, and chemical treatment
How to Test Your Hair Porosity at Home
The Float Test
Take a clean strand of hair (free of product) and place it in a glass of room-temperature water. Wait 2–4 minutes and observe:
• Floats on the surface: Low porosity — cuticle is tightly sealed, water has difficulty entering the shaft
• Sinks slowly to mid-glass: Medium porosity
• Sinks quickly to the bottom: High porosity — water enters the shaft immediately
Note: this test is imperfect — hair cleanliness, the presence of oils, and other factors can affect the result. Use it as a guide, not a diagnosis.
The Slip-and-Slide Test
Take a clean hair strand and slide your fingers from tip toward the root. If you feel bumps and roughness moving toward the root, your cuticle scales are raised — indicating higher porosity. If it feels smooth, your cuticle is lying flat — lower porosity.
How Porosity Affects How You Should Use Reytha Products
Low porosity hair + Reytha Shampoo
Focus shampoo on the scalp. Use lukewarm water to slightly open the cuticle for better cleansing. Avoid leaving conditioner on too long without heat — add a warm towel wrap during conditioning to help the formula absorb. Use a clarifying wash every 4–6 weeks to remove surface build-up.
High porosity hair + Reytha Shampoo and Conditioner
The Castor Oil and Coconut Oil in Reytha's formula are particularly well-suited to high porosity hair — their molecular structure allows them to partially fill cuticle gaps, temporarily improving smoothness and reducing moisture loss. Follow shampoo with Reytha Conditioner and rinse with cool water to close the cuticle as much as possible. Layer with a leave-in treatment if needed.
"Your hair tells you what it needs. Porosity is just the language it's speaking. Learn to listen."
The Indian Hair Porosity Conversation
Indian hair tends toward the medium-to-low porosity range in its natural, unchemically treated state — particularly straight and wavy hair textures common across northern and western India. The coarser, naturally curlier hair textures more common in South India and among tribal communities tend toward naturally higher porosity.
Chemical treatments — straightening with sodium hydroxide or formaldehyde-based relaxers, which are extremely common in Indian urban centres — dramatically increase porosity. If you've had any chemical treatment, your hair's porosity is almost certainly higher than its natural baseline.
Hard water, common across most Indian cities, also gradually increases hair porosity through the mechanical disruption of mineral deposits on the cuticle. This is why understanding and addressing porosity is particularly relevant for Indian hair care.
