Understanding Hair Porosity
Do You Know Your
Hair's Porosity?
One glass of water. One strand of hair. Two minutes. Everything you need to understand how your hair absorbs — and holds onto — moisture.
There's a reason some people can apply a rich cream to their hair and feel instantly nourished, while others find the same product leaves their strands greasy and weighed down. Or why your deep conditioning treatment seems to do nothing, no matter how long you leave it on. The answer — more often than not — comes down to a single word: porosity.
Hair porosity refers to your hair's ability to absorb and retain moisture. It's determined by the state of your hair cuticles — the tiny, overlapping scales on the outer layer of each strand, much like shingles on a roof. How tightly or loosely those cuticles sit determines everything about how your hair drinks up water and products.
The Three Types of Porosity
Before reaching for the glass of water, it helps to understand what you're testing for. There are three distinct porosity levels, each with its own personality and its own needs.
Tightly closed cuticles. Hard to absorb moisture, but great at holding it in once it's there.
Balanced cuticles. Absorbs and retains moisture well — the easiest type to care for.
Lifted or damaged cuticles. Absorbs moisture quickly but loses it just as fast.
The Float Test: Step by Step
This is the easiest and most reliable at-home test to determine your hair porosity. You only need three things: a clean strand of hair, a glass of water, and a few minutes. The key is to start with a clean, product-free strand — any residue from dry shampoo, oils, or leave-in products can give you a false reading.
How to Do the Float Test
You'll need: a clear glass, room-temperature water, and a clean hair strand.
Start with clean hair
Wash your hair with a gentle clarifying shampoo and let it dry fully before testing. Product buildup is the #1 cause of inaccurate results.
Fill a glass with room-temperature water
Use a clear glass so you can see exactly where the strand sits. Avoid hot or cold water — extreme temperatures can temporarily alter how the hair behaves.
Drop in a single strand
Gently place one clean, dry strand into the water and resist the urge to stir or move it. Let it settle naturally.
Observe for 2–5 minutes
Watch where the strand goes — and how quickly. The timing matters just as much as the final position.
Reading Your Results
Once you've watched the strand for a few minutes, the position it settles in tells your porosity story. Here's what each result means for your hair.
Strand floats at or near the surface for several minutes before slowly sinking — if it sinks at all.
Strand floatsStrand slowly drifts down and hovers somewhere in the middle of the glass.
Strand floats mid-glassStrand sinks quickly and lands at the bottom of the glass within a minute or two.
Strand sinks fastWhat to Do With Your Results
Knowing your porosity unlocks the logic behind what works and what doesn't for your hair. Each type requires a specific approach — and once you align your routine with your porosity, the difference is immediate.
Low Porosity
- Use warm or hot water to gently open cuticles before washing
- Choose lightweight, water-based products that won't cause buildup
- A heated conditioning cap helps moisture actually penetrate
- Clarify regularly — this type is prone to product sitting on the surface
- Avoid heavy butters and oils as your primary moisturizer
Medium Porosity
- Maintain with regular deep conditioning — don't neglect it
- Most product formulas work well, so explore freely
- Protect from heat and chemical treatments to stay in this zone
- A monthly protein treatment keeps cuticles healthy and sealed
- Enjoy the flexibility — this is the most cooperative hair type
High Porosity
- Use cold water rinses to help close the cuticle after washing
- Seal moisture in with heavier creams or butter-based products
- Protein treatments are your best friend — use them regularly
- Layer products: hydrate first, then seal on top
- Avoid excessive heat styling, which worsens porosity over time
The Slip Test (Bonus)
- Run your fingers from the tip toward the root on a dry strand
- Smooth and slippery = low porosity
- Slight texture or small bumps = medium porosity
- Very rough, catches on fingers easily = high porosity
- This confirms your float test result — do both for accuracy
One More Thing to Know
Your hair's porosity isn't necessarily the same from root to tip — especially if you color, heat-style, or chemically treat your hair. The ends tend to be more porous than the roots simply due to age and exposure. It's worth testing a strand from different sections of your hair to get the full picture.
Porosity can also shift over time. Frequent bleaching, relaxing, or even prolonged sun exposure can raise your porosity level. On the flip side, a consistent, porosity-informed routine can help restore medium porosity over time — especially with regular protein and moisture balance.
Hair care becomes a lot less frustrating once you stop asking "why isn't this working?" and start asking "what does my hair actually need right now?" Porosity is the lens that makes everything click. Once you know it, you know it.
"Your hair isn't difficult. It's just misunderstood."
