Hair porosity

The internet wants you to drop a strand of hair into a glass of water and wait for it to reveal its personality. Hair porosity is real. The float test is not nearly as useful as TikTok made it look.

Porosity is basically how readily your hair takes up and loses water. It is influenced by the condition of the cuticle, The overlapping outer layer that protects the inside of the hair fibre.

Bleach, chemical treatments, UV exposure, repeated heat and general wear can damage that surface and make hair more porous. But you do not need to assign every strand on your head a permanent low, medium or high label.

Step 1: Skip the float test

The usual test says:

• Hair floats = low porosity
• Hair sits in the middle = medium porosity
• Hair sinks = high porosity

The problem is that floating and sinking are affected by more than porosity. Oil, conditioner residue, styling products, the individual strand and the surface tension of the water can all change what happens.

So do not rebuild your entire routine because one hair sank in a glass.

Step 2: Watch what your hair actually does

Start with freshly washed hair and pay attention over two or three normal wash days. You are looking for a pattern, not one perfect test.

One important catch: drying time by itself does not diagnose porosity. Hair density, strand thickness, length, humidity and how much hair you have all affect how long drying takes. Look at the full pattern.

Step 3: Check your history

This is often more useful than any DIY test.

If your roots behave normally but your ends absorb everything, tangle, frizz and feel rough, your hair did not suddenly develop two personalities. The older lengths have simply been through more.

Colouring, bleaching, straightening, repeated high heat and environmental damage can make the hair fibre more porous over time.

Damage can change porosity. That is why the same routine may stop working after you bleach or chemically treat your hair.

If your hair seems lower porosity

• Use less product before assuming you need a different product.
• Choose lighter conditioners and leave-ins if heavy formulas sit on top.
• Apply conditioner thoroughly to wet hair and give it time to spread through the lengths.
• Clarify when buildup starts making the hair feel coated or unusually heavy.
• Do not keep adding oil because your hair “isn’t absorbing enough.” More is not always better.

Low porosity is not a problem that needs fixing. If your hair feels good, leave it alone.

If your hair seems medium porosity

Congratulations, your routine probably does not need a personality test.

• Condition regularly.
• Use heat protection when styling.
• Do not add treatments just because someone online told you medium porosity needs them.
• Keep doing what is already working.

If your hair seems higher porosity

• Condition every wash.
• Use a leave-in if your lengths dry out quickly.
• Silicones and other smoothing ingredients can reduce friction and improve feel.
• Use heat protectant every time you heat style.
• Reduce repeated bleaching and unnecessary chemical processing.
• Trim ends that are splitting, gummy or repeatedly snapping.

Products can smooth damaged hair and make it easier to manage. They cannot permanently rebuild a cuticle that has already been lost.

What about protein?

Porosity does not automatically tell you that you need protein. High-porosity hair is often damaged, but that does not mean every wash needs a protein mask.

If a protein treatment makes your hair feel smoother and stronger, fine. If repeated use leaves it stiff, rough or difficult to detangle, use it less often. Your hair's response is more useful than the label.

What porosity cannot tell you

Porosity does not tell you your:

• Hair density
• Strand thickness
• Curl pattern
• Scalp type
• Cause of hair fall
• Perfect shampoo

Two people can both have highly porous hair and still need completely different routines.

The BYOUT porosity test

Forget the glass of water. Ask yourself these instead:

1. Does my hair take a long time to become fully wet?
2. Do products sit on top or weigh it down easily?
3. Does my hair become rough or dry again soon after conditioning?
4. Do my ends behave differently from my roots?
5. Has the behaviour changed since bleaching, colouring or frequent heat styling?

Your answers over several wash days will tell you more than one strand floating in a cup.

Honest expectations: porosity is useful when it helps explain how your hair behaves. It stops being useful when it becomes another category you are trying to perfectly diagnose.

The short version: if products sit on your hair, use less and go lighter. If your hair absorbs everything and still feels rough, condition and protect it better. If your ends are damaged, treat them like damaged hair rather than trying to change their “porosity type.”

Treat the behaviour, not the label.

The BYOUT Library is educational content, not personalised medical advice. For persistent hair loss, scalp disease or sudden changes in your hair, a dermatologist beats any article, including ours.