Hair porosity test, find your type and the routine that actually works for your hair
Quick Answer Summary
The short version before you read on
What hair porosity actually is
Hair porosity refers to how well your hair's cuticle layer allows moisture and products to enter and exit the hair shaft. The cuticle is made up of overlapping scales, like roof tiles. When these scales lie flat and tightly closed (low porosity), moisture struggles to get in but stays in well once absorbed. When they are raised or have gaps (high porosity), moisture enters easily but escapes just as quickly. Medium porosity sits in the middle, balanced absorption and retention.
Why the float test is unreliable
The float test, dropping a strand in a glass of water to see if it sinks, is the most widely recommended porosity test. It is also the least accurate. Whether hair floats or sinks depends more on product buildup, the weight of the strand, and how clean the hair is than on porosity. A single strand coated in conditioner will sink regardless of porosity. The behavioural questionnaire approach, how your hair actually responds to moisture, oil, and products over time, is significantly more reliable.
Why porosity changes which products work
Low porosity hair needs lightweight oils and the warm towel method to help products penetrate sealed cuticles. Heavy oils just sit on the surface. High porosity hair needs heavier, sealing oils applied to damp hair to trap moisture before it escapes. The same oil that transforms high porosity hair will weigh down and build up on low porosity hair. Protein treatments are beneficial for high porosity (fills cuticle gaps) but cause stiffness and breakage on low porosity. Rice water, popular for everyone, should be limited to monthly for low porosity, weekly for high.
Can porosity change?
Your natural baseline porosity is determined by genetics, specifically the structure of your hair cuticle. However, chemical processing (colour, bleach, relaxers), heat damage, and mechanical damage all raise cuticle porosity permanently in the damaged sections. New growth comes in at your natural baseline. This is why chemically treated or heat-damaged hair is almost always high porosity even in people who are naturally low or medium porosity. Trimming damaged sections is the only way to "restore" porosity, you cannot reverse cuticle damage on existing hair.
In this article
Hair porosity is one of the most practically useful concepts in hair care, and one of the most misunderstood. It explains why some people's hair feels perpetually greasy despite minimal oiling, why some hair is always dry despite constant conditioning, and why rice water transforms some people's hair while making others' stiff and brittle. It is not about hair type, hair texture, or genetics alone, it is about the physical structure of the cuticle and how that structure affects everything you put on your hair.
The science of hair porosity, what determines it
Each hair strand is covered by a cuticle, a layer of overlapping scales made of a protein called alpha-keratin. These scales point from the root toward the tip, like roof tiles. The state of these scales determines porosity: when they lie flat and tight, moisture has difficulty penetrating but stays in well once it gets in (low porosity). When they are lifted, damaged, or have gaps between them, moisture enters easily but escapes just as fast (high porosity).
Your natural cuticle structure is largely genetic, inherited alongside hair texture, thickness, and growth rate. But cuticle structure changes with chemical and heat damage. Bleaching raises and erodes the cuticle permanently. Chemical relaxers break disulfide bonds in the cuticle layer. Repeated heat styling from flat irons and blow dryers gradually erodes cuticle scales. This is why chemically treated hair typically behaves like high porosity hair even in people who are naturally low or medium porosity, the treatment has changed the cuticle structure of those strands permanently.
Why the float test doesn't work
The widely recommended float test involves placing a clean strand of hair in a glass of water and waiting to see if it floats (low porosity) or sinks (high porosity). The problem: whether a strand sinks or floats depends on product buildup, strand weight, surface tension, and how recently the hair was washed, not primarily on porosity. In studies of the test's reliability, results are highly inconsistent and don't correlate reliably with actual cuticle structure. The behavioural signs approach, how your hair responds to moisture, products, drying time, and humidity over time, is a significantly more accurate method.
The three porosity types, what each looks and feels like
💎 Low porosity. Cuticles are tightly closed and lie completely flat. Water beads off initially before eventually absorbing. Hair takes a very long time to dry. Products tend to sit on the surface rather than absorbing, leading to buildup and a weighted, greasy feeling. The upside: once moisture is absorbed, low porosity hair retains it exceptionally well. Natural shine is high. This type is very sensitive to protein, protein treatments cause stiffness and breakage quickly because the cuticle is already well-sealed and doesn't need the filling that protein provides.
⚖️ Medium porosity. Cuticles are slightly raised, open enough to absorb moisture at a moderate rate, but not so open that moisture escapes quickly. The most manageable type. Hair absorbs products evenly, holds styles well, and requires the least specific intervention. Medium porosity hair tolerates protein, responds well to rice water, and works with a wide range of oils. The primary goal for medium porosity is maintenance, keeping it from shifting toward high porosity through damage prevention.
🌊 High porosity. Cuticles are significantly raised, damaged, or have structural gaps, often from chemical processing, heat damage, or mechanical stress. Water absorbs instantly but evaporates quickly, leaving hair feeling dry even after conditioning. High frizz in humidity. Hair absorbs oils quickly but the moisture doesn't stay long. Benefits significantly from protein treatments (inositol from rice water and keratin fill the cuticle gaps, reducing porosity temporarily) and heavier sealing oils applied to damp hair.
| 💎 Low | ⚖️ Medium | 🌊 High | |
|---|---|---|---|
| Water absorption | Slow, beads off | Moderate | Instant |
| Drying time | Very long | Normal | Fast but dries out |
| Best oils | Lightweight, Argan, Jojoba | Most oils work | Heavier, Castor, Coconut |
| Protein tolerance | Low, avoid frequent protein | Good, monthly is fine | Loves protein, weekly |
| Rice water frequency | Once a month maximum | Once a week | Weekly, highly beneficial |
Hair porosity test, find your type
Answer 8 questions about how your hair actually behaves, with water, products, drying, and humidity. Answer based on your hair's natural tendencies, not a recent colour or treatment. The test gives you your porosity type, a breakdown score, dos and don'ts, a personalised routine, and product and reading recommendations matched to your type.
Oils by porosity, which penetrate and which seal
Not all oils behave the same way on hair. Some oils are small enough molecularly to penetrate the hair shaft, reducing protein loss and conditioning from within. Others are too large to penetrate and sit on the cuticle surface as a sealant, reducing moisture loss by creating a barrier. The distinction matters enormously for porosity-matched oiling.
Penetrating oils (small molecular weight, enter the shaft): Coconut oil, Avocado oil, Olive oil. These are beneficial for all types but especially high porosity, they reduce protein loss from the compromised cuticle. For low porosity hair, use sparingly as they still add weight even when penetrating.
Sealing oils (large molecular weight, coat the surface): Castor oil, Argan oil, Jojoba oil, Grapeseed oil. These create a barrier on the cuticle that slows moisture loss. For high porosity hair, apply over a leave-in conditioner to seal in the moisture. For low porosity hair, lightweight sealants like Argan and Jojoba are preferred over heavy ones like Castor which will weigh the hair down without penetrating.
Satthwa Premium Hair Oil contains both penetrating (Coconut, Olive, Avocado) and sealing (Argan, Jojoba, Castor) oils, making it suitable for all porosity types. The application method changes by type: low porosity uses it on damp hair with warmth; high porosity applies it generously after washing to seal in moisture.
Protein and rice water, when they help and when they hurt
Rice water is one of the most popular hair treatments in India right now, but its effect is entirely porosity-dependent. The active benefit of rice water is inositol, a compound that penetrates damaged hair and temporarily fills cuticle gaps, strengthening the shaft and reducing breakage.
For high porosity hair, rice water is highly beneficial, the inositol fills the gaps in the raised cuticle, temporarily reducing porosity and making hair feel stronger and less frizzy. Weekly use is appropriate.
For medium porosity hair, rice water works well at moderate frequency, once a week is the maximum before protein saturation begins to cause stiffness.
For low porosity hair, rice water should be used sparingly, once a month at most. Low porosity hair's tightly sealed cuticle means inositol can't enter easily, so it builds up on the surface instead, causing the classic protein overload symptoms: stiffness, brittleness, and snapping. This is the most common reason low porosity people report that rice water "damaged their hair", the damage is actually protein overload from too-frequent use. Read more: rice water for hair, the complete guide.
Frequently asked questions
The bottom line
Hair porosity is the single most useful concept for understanding why your current hair routine is or isn't working. Low porosity hair needs lightweight products, the warm towel method, and limited protein. High porosity hair needs heavier sealing oils on damp hair, regular protein treatments, and pH-balanced shampoos that don't further open the cuticle. Medium porosity is the most forgiving but benefits from consistency and damage prevention. Use the test above to find your type and follow the matched routine, the difference between a porosity-matched routine and a generic one is significant enough to notice within a few weeks.
