What is Porosity?

What porosity actually means

Porosity is your hair's ability to absorb and hold moisture. It's determined by the structure of your cuticle — the outer layer of each strand — and it shapes which products will work for you and which will sit on top doing nothing.

The three levels

• Low porosity: tight cuticles. Moisture slides off; products sit on the hair. Needs heat and lightweight, water-based formulas.
• Medium porosity: cuticles are balanced. The easiest to manage — most routines work.
• High porosity: raised or damaged cuticles. Moisture enters fast but leaves just as fast. Needs richer butters and sealants to hold hydration in.

How to test it

The float test is a quick starting point: drop a clean strand in a glass of water. Sinks fast = high porosity; floats = low; sinks slowly = medium. But the real test is how your hair behaves — does product sit on top, or drink right in?

Why it changes your routine

Low-porosity hair loves heat and humectants; high-porosity hair craves protein and sealants. Buying the "best" product on the shelf means nothing if it's the wrong match for your porosity.

The takeaway

Know your porosity first. Then choose. Your hair will tell you what it needs — you just have to listen.