Understanding Hair Porosity and It’s Impact on Hair Care

By Rebecca Anderson, Salon Owner and Trichologist

Hair porosity refers to your hair’s ability to absorb and retain moisture, which is largely influenced by the structure of your hair cuticle. The cuticle layer —the outermost layer of the hair—acts as a protective shield. Its openness or tightness determines how easily water and nutrients penetrate and stay in your hair.

While all hair types have some degree of porosity, curly hair is often more affected due to its natural tendency to lose moisture quickly. Understanding your hair’s porosity is essential for crafting an effective hair care routine, ensuring optimal hydration, and maintaining overall hair health.

Porosity in Science

Scientifically, porosity measures the amount of empty space within a material and is expressed as a ratio or percentage. In simple terms, think of it like a sponge: the more “voids” or spaces, the more water it can absorb. Similarly, hair porosity refers to the cuticle’s permeability.

​A sponge is an example of a porous material as it has a large percentage of empty spaces covering its outer surface.

When chemists talk about the porosity of hair they simply refer to it as degrees of damage.

Why Hair Porosity Matters

Porosity directly affects how your hair absorbs and holds onto moisture, impacting everything from hydration to product effectiveness. Porosity level can be divided into three categories:

• Low porosity: Moisture struggles to enter the hair.
• Medium porosity: Moisture is well-balanced.
• High porosity: Moisture enters easily but escapes just as quickly.

Types of Hair Porosity

Low Porosity

Characteristics:

• Cuticles are tightly packed, making it hard for moisture to penetrate.
• Often healthy but can feel dry or resistant to treatments.

Care Tips:

• Use lightweight, conditioning treatments like aloe vera or glycerin-based conditioners.
• Pre-shampoo treatments or oils can help prepare the hair for moisture absorption.
• Avoid heavy oils or butters that may sit on the surface and cause buildup.

Medium/Normal Porosity

Characteristics:

• Looser cuticle layers allow moisture to enter and stay balanced.
• Requires minimal maintenance.

Care Tips:

• Use balanced hair care products without overloading on proteins or oils.
• Include occasional treatments to maintain health, like a Kérastase Résistance mask for protein balance.

High Porosity

Characteristics:

• Gaps in the cuticle allow moisture to enter but make retention difficult.
• Often caused by damage from heat, chemicals, or environmental exposure.
• Prone to frizz, dryness, and breakage.

Care Tips:

• Focus on repairing damage with protein-rich products to strengthen the cuticle.
• Lightweight, hydrating products can help reduce frizz without weighing hair down.
• Limit heat styling and use cool water to close the cuticle during washing.

How to Test Your Hair Porosity

1. The Float Test:

• Drop a strand of clean hair into a glass of water.
• Low porosity hair floats, medium porosity sinks slowly, and high porosity sinks quickly.

2. The Backcomb Test:

• Select a small section of hair, hold the ends and slide your thumb and forefinger along the hair strand toward the scalp.
• The more rough the hair feels and the easier the hair backcombs the greater the porosity.

Note: Testing can help you better understand your hair type, but results should be combined with observation and professional advice.

Choosing the Right Products Based on Porosity

Low Porosity:

• Look for humectants like glycerin, aloe vera, and honey.
• Avoid heavy products that may lead to buildup.

Medium Porosity:

• Use balanced formulations that maintain moisture and protein levels.
• Occasional strengthening treatments are beneficial.

High Porosity:

• Protein treatments repair damage and fill in gaps in the cuticle.
• Avoid overusing heavy oils; opt for lightweight hydration.

Common Mistakes in Hair Porosity Care

• Skipping Clarification: Low-porosity hair is prone to buildup, so use a clarifying shampoo occasionally.
• Overusing Heat and Chemicals: These can worsen porosity levels, especially in high-porosity hair.
• Choosing the Wrong Products: Heavy products can overwhelm low-porosity hair, while light hydration isn’t enough for high-porosity hair.

Expert Tips for All Hair Types

• Hydration is Key: Use hydrating products suited to your porosity.
• Seal in Moisture: Follow hydration with a sealing product like a serum or lightweight oil.
• Regular Trims: Prevent split ends and maintain healthy hair.
• Adapt Routines Seasonally: Your hair may require different care in humid vs. dry climates.

Hot Tip: For high-porosity hair, rinse with cool water to encourage the cuticle to close, locking in moisture for a smoother finish.

Take Control of Your Hair Health

Understanding your hair’s porosity is the first step to achieving your healthiest hair yet. Try a hair porosity test and adapt your routine with targeted products to meet your hair’s specific needs.

For more information, check out some further reading:

Chemist’s Corner
Cosmetics & Toiletries Magazine

By understanding the science of porosity, you can transform your hair care into a regimen that delivers real, noticeable results.