Understanding Hair Porosity: The Key to Your Best Curls

Hair porosity is one of the most important — and most misunderstood — factors in curly hair care. Once you understand yours, everything from product selection to wash day routines starts to make sense.

What Is Hair Porosity?

Porosity refers to your hair's ability to absorb and retain moisture. It's determined by the structure of your hair's cuticle — the outermost layer made up of overlapping scales, like roof shingles.

There are three levels:

• Low porosity — cuticles lie flat and tightly packed, making it hard for moisture (and products) to enter
• Medium (normal) porosity — cuticles are slightly raised, allowing moisture in and out at a balanced rate
• High porosity — cuticles are raised or damaged, absorbing moisture easily but losing it just as fast

How to Test Your Porosity at Home

The Float Test

Drop a few clean, dry strands of hair into a glass of room-temperature water and wait 2–4 minutes.

• Floats at the top → Low porosity
• Sinks slowly to the middle → Medium porosity
• Sinks to the bottom quickly → High porosity

The Slip 'n' Slide Test

Slide your fingers up a single strand from tip to root.

• Smooth with no bumps → Low porosity
• Slight texture → Medium porosity
• Rough or bumpy → High porosity

Caring for Each Porosity Type

Low Porosity Hair

The challenge: products sit on top instead of absorbing in.

Tips:

• Apply products to soaking-wet hair — water already on the shaft helps carry ingredients inside
• Use light, liquid-based products rather than heavy butters
• Try the greenhouse effect: apply your leave-in conditioner, then sit under a hooded dryer or steamer to open the cuticle
• Avoid protein-heavy products, which can cause build-up and stiffness

Medium Porosity Hair

You have hit the sweet spot. Your hair is the most forgiving and responds well to a wide range of products.

Tips:

• Maintain this balance with regular deep conditioning
• Avoid excessive heat and chemical processing to keep cuticles intact
• Most product types and techniques will work well for you

High Porosity Hair

The challenge: moisture escapes almost as fast as it enters.

Tips:

• Use heavier creams and butters to seal moisture in
• Finish with an oil (like castor or jojoba) to coat the cuticle and slow moisture loss
• Try protein treatments periodically to fill gaps in the cuticle
• Cold water rinses help close the cuticle temporarily after washing
• The LOC method (Liquid to Oil to Cream) works especially well for high-porosity hair

Porosity Changes Over Time

Porosity is not fixed forever. Chemical processing (colour, relaxers, bleach), heat damage, and UV exposure can shift low-porosity hair toward high porosity. Trimming damaged ends and reducing heat use can help improve porosity over time.

How CurlyRoutine Uses Porosity

When you scan your hair with the CurlyRoutine AI, porosity is one of the three core data points — alongside curl type and density — used to generate your personalised routine. Instead of guessing which products might work, you get recommendations matched specifically to how your hair absorbs and retains moisture.

Understanding your porosity is the first step to a routine that actually works.