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Hair Porosity 101: The Ultimate Guide

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Table of Contents

Image of three different curly hair types revealing the hair porosity levels - low, medium, and high.

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Hair porosity is rarely talked about in hair care guides or by professionals. Visiting your hairdresser and hearing them tell you how to choose products based on your porosity is unlikely. But that is because there is a science to it. So, here I will give you the ultimate guide on hair porosity. 

Hair porosity defines the hair’s appearance and condition based on pore size, volume, and density on the hair shaft. All hair is porous – meaning it absorbs moisture. There are three porosity levels (low, medium, and high), and determining your type can help you access better products and regimes. 

I am fortunate know a friend who’s not only a seasoned cosmetic formulator but also holds a PhD in Chemistry. With his expertise, we’ve delved into the science of hair care, specifically focusing on hair porosity. Together, we’ve compiled this guide covering the essentials of hair porosity, including its influencing factors, how to determine your own, and strategies for effective hair management. I’m excited to share these insights with you through this blog post!

Understanding Hair Porosity 

Infographic showing hair porosity levels - low, medium, high.

Hair porosity is a frequent issue for consumers and hair care experts. By pushing our hair too far with extreme grooming techniques or damaging chemical treatments, protein loss causes the shafts to become more porous over time – an unenviable result of these practices. 

But what exactly is hair porosity? Hair porosity is a technical term that defines the hair’s macroscopic appearance and microscopic condition. The word “Porosity” is derived from “pore” and describes the pore size, volume, and density on the hair shaft.  

In simple terms, porosity is about damage; the more damaged your hair is, the more porous it is.

Cuticles are the most outer layer of the hair shaft, while the cortex and medulla are the inner structural units of the hair fiber. 

Hair fiber appears as a compact cylinder with firmly cemented cuticles and cortex. The cuticle layer contains tiny pores through which water molecules, active conditioning ingredients, coloring molecules, and polymers penetrate and go deep inside the hair fiber. 

Infographic showing the cortex, medulla, and cuticle of hair.

All hair is porous. The degree of porosity is an indication of how damaged your hair is. The more porous your hair is, the more damaged it is. Factors like chemical treatments, UV radiation, brushing hair excessively or too harshly, etc., can cause hair cuticles to become damaged. 

Depending on the severity of the damage, the inner cortical components can be exposed, leading to an increase in pore size and volume and a significant increase in the number of pores (pore density) over the hair shaft. 

Does Hair Porosity Matter? 

We should never subscribe to a one-size-fits-all mentality regarding our hair, as no two types are alike. Everyone’s hair requires special attention and individualized care to look and feel their best – but how does one know what kind of products are needed? Hair porosity is your answer. 

Porosity matters as it is the first indication of your hair quality. Poor porosity leads to poor hair health, luster, shine, texture, and body. Unfortunately, those with porous hair are familiar with copious amounts of unruliness, as their strands often resist styling and settling into the desired shape. 

As you run your fingers through your hair, it feels unpleasantly rough due to cuticle loss. Consequently, this imparts a lifeless and lackluster look since less light is reflected from its rough surface. Porosity is a crucial metric of hair quality that should be closely monitored. 

If the porosity level becomes too high, there can be severe consequences, such as breakage during brushing and combing, leading to thinning hair. Therefore, keeping your porosity in check and addressing any issues quickly before it worsens is crucial. 

Different Hair Porosity Types and Causes 

Image of hair porosity graphic describing low, medium, and high porosity levels.

Hair experts have characterized hair fibers into three distinct levels of porosity.

The characterization varies with increasing degrees of porosity. Hair porosity is not static; it shifts whenever hair texture and structure are modified or harmed. The more damage your hair has endured, the higher its porosity becomes. 

Low Porosity Hair 

This level possesses small openings and pore sizes. Hair with low porosity is typically healthier virgin and not chemically treated. Low porosity hair cannot absorb moisture easily due to its dense cuticles that lay flat. Additionally, it repels water better than other types of hair. 

Low-porosity hair has minimal porosity and can still experience damage from prolonged exposure to UV light, the natural aging process, aggressive combing/brushing, rough handling, etc. The ends become more porous as hair grows while the roots remain in good condition. 

Medium Porosity Hair 

Medium porosity hair does not suffer a high degree of cuticle damage, often caused by continuous heat styling, perming, and over-brushing. It stands between low and high porosity and is characterized by medium cuticle openings and pores. It retains and absorbs water well.  

High Porosity Hair

Image showing different levels of hair damage.

When hair is damaged, tiny cracks in its protein structure develop, eventually leading to pores. These visible signs of damage indicate that the hair has been compromised. 

Some characteristic features or indicators of porous hair are: 

  • The rough texture is undeniable as you glide your fingers across your hair. 
  • Your hair absorbs moisture quickly and dries off just as quickly. 
  • Your hair is frizzy. 
  • You have difficulty combing, styling, and managing your hair. 
  • Your hair may be fluffy and poofy. 
  • Your hair may feature many open pores with a larger size, caused by protein loss which results in large empty spaces within the strands.1,2,3   
  • You find that your hair has raised, broken, and (sometimes missing) cuticles, allowing it to easily absorb water and lose it just as quickly. This results in difficulty maintaining moisture levels, leading to frizzy, dry, brittle hair. 

Depending on the severity of the damage, the inner cortex materials can be fully exposed to the outer environment. Additionally, if the hair is too compromised to save with no cuticle left on the strands, the hair is considered degraded. 

Degraded strands have completely unattached cuticles that can cause excessive breakage and shedding. If your hair’s porosity is classified as degraded, the only way to repair it is by cutting off the damaged ends and starting anew. 

Factors that Can Increase Porosity

Hair is susceptible to a wide range of harm. Various factors can considerably alter your hair porosity, some more drastically than others. 

These components include: 

  • Environmental Factors: UV exposure from sunlight, chlorine, and saltwater can all contribute to cuticle damage. 
  • Chemical Treatments: Using harsh products, over-processing hair with bleaching or coloring treatments, and other chemical services (i.e., alkaline hair straightening using sodium hydroxide or guanidine hydroxide) can all considerably raise the porosity of your strands. 
  • Heat Damage: Using hot styling tools, such as curling tongs, flat irons, and blow dryers, can result in heat damage to the cuticles. 
  • Mechanical Damaging Practices: Brushing too harshly, rough handling your hair, or using a fine-toothed comb. The abrasive texture of a cotton towel or pillowcase can be harsh on your cuticles, leading to broken cuticles and increasing porosity. 

How to Identify Your Hair Porosity 

High-tech experimental protocols are used by hair scientists to accurately assess the porosity of hair. These test procedures thoroughly analyze single hair fibers to evaluate both the quality and quantity of the sample, resulting in a numerical value that reflects its exact porosity level.4,5,6 

Unfortunately, as consumers, we lack access to these advanced machines and need an easy method to measure our hair’s porosity- whether at a salon or within the comfort of our homes. Hair experts have developed a range of simple assessments to evaluate our hair porosity. 

Float Test

Infographic of hair porosity test called the float test.

The float test is more scientifically reliable than other methods discussed on the web and better reflect actual assessment results. 

Here is a step-by-step guide on how to conduct the float test to determine the porosity of your hair: 

  • Take a single hair fiber from your comb or brush. Make sure the hair is clean. 
  • Fill a small bowl or cup at room temperature (68-74 degrees F) because temperature greatly influences wet hair. 
  • Gently place the single hair strand in the water, being mindful not to disturb the water’s surface. 
  • Observe each hair strand and note how long it takes for the single strand to sink to the bottom. 
  • Highly porous hair will quickly absorb water, so it takes little time for high-porosity hair to get wet. 
  • Medium porosity hair will slowly sink, but not as fast as high porosity hair. 
  • If the hair strand floats, then it is likely that you have low-porosity hair. 
  • Repeat this experiment using color-treated or bleached hair fibers to provide further evidence of the results. This will reveal the variance in porosity between different types of hair. 

Note: Hair has various porosity levels from its roots to the ends, which makes it difficult to accurately determine the true porosity level. The float test cannot reveal this; however, the ends of your hair is more likely highly porous (due to natural wear and tear and other factors) compared to the new growth at the root area which will have lower porosity.

Characteristics of Different Porosity Levels 

It’s not entirely impossible to roughly conclude your porosity type. Each hair porosity level has distinct properties and can easily be identified through particular characteristics.

Low PorosityMedium PorosityHigh Porosity
Cuticle layer intact.Partially compromised.Cuticle layer is compromised (or may be eroded).
Hair in good condition (healthy).Relatively less damaged.Extremely damaged.
Low hair breakage upon applying pressure when combing or brushing.Hair does not break easily.Lots of hair breakage.
Low frizz.Moderate frizz.Lots of frizz.
Hair feels good and only shows roughness toward the ends of hair.Low to moderate roughness.Extremely rough and dry.
Hair is not greatly affected by extreme humidity fluctuactions.Moderate response to high humidity conditions.High uptake of moisture from its surroundings.
Hair behave as normal during hair coloring and color appears uniform.Moderate dye uptake during hair coloring.High uptake of coloring molecules or pigments during hair coloring application. Color does not appear smooth and uniform.

Can Your Hair Porosity Level Change? 

Hair porosity levels can change. They can transition from low to high porosity and the other way around.

The transformation can occur over time or when affected by external elements like chemical treatments, heat styling tools, weather elements, and more. 

Let’s look at how those changes in porosity level happen and the science behind their effect on the hair: 

An Increase in Hair Porosity Level: Low to High 

Low-porosity hair is virgin hair. It is non-chemically treated. When hair is exposed to harsh chemicals such as bleach or permanent dye, it can become stripped of its proteins and suffer damage. That leaves the hair with an increased porosity level. 

During these harsh oxidation processes, proteins in the hair react, and amino acids oxidize. The oxidized protein byproducts are soluble in water and will be washed away with a regular shampoo session. 

Ultimately, hair loses its proteins and cuticles, increasing pore size with greater pore density. As a result, low-porosity hair evolves into high-porosity hair. 

A Decrease in Hair Porosity Level: High to Medium 

With proper hair care, high porosity levels can be reduced. When that happens, your hair can regain its original sheen, strength, and healthy appearance. 

The process requires repeated application of hydrating, conditioning, and fiber-strengthening formulations.

These fiber reconstructor formulations comprise vegetable proteins, keratins, and micro-polymer molecules. 

Proteins are known and scientifically proven to restore the hair’s mechanical strength and recover its natural gloss.7 Cationic conditioning polymers can improve fiber quality and combat their high porosity. 

Consistently using a proper hair care regimen can improve fiber porosity and eventually convert high-porosity hair to low/medium-porosity hair.  

My hair is an example of this. My hair had severe damage and high porous levels due to flat irons, bleaching, and other chemical treatments.

After using a combination of treatments, my porosity level was back on track (as seen in the before and after photos below).

Some of the treatments I included are: 

Image of my hair when it was damaged and healthy. Hair Porosity 101: The Ultimate Guide.

How to Change Your Hair Porosity Level 

Now that you know your hair porosity level can be transformed, you may try it based on your needs. You can change your porosity with a combination of treatments and a consistent hair care regime. This can help you transition from damaged hair to healthier hair. 

These are some tips to help you manage your hair porosity: 

Tips for Low-Porosity Hair 

It can be alluring to layer on several hair products to moisturize low-porosity hair; however, that approach does not always provide the best results.

Low porosity hair with tightly packed cuticles can’t absorb large amounts of product, resulting in excess product build-up. 

  1. It is best to look for ingredients that can easily penetrate your hair and nourish it from within., allowing you to use fewer products but still get beneficial results. 

2. To restore moisture to your hair, search for products that are specifically formulated for low-porosity hair, such as: 

3. Don’t be afraid to use protein. Many people shy away from proteins or don’t know which type to incorporate, but properly balanced proteins can help smooth the cuticle and prevent breakage. 

4. Maximize your deep conditioning potential with the help of heat (i.e., steamers) to lift the hair cuticles, giving it full access to nourishment from your conditioner. 

Tips for High Porosity Hair 

Unlike low porous hair, high porous hair has the unique advantage of holding multiple layers of product simultaneously for added nourishment and moisture

  1. Blending a synergistic selection of protein-rich and moisturizing products will yield the best results. 
  2. To restore moisture to your hair, search for products that are specifically formulated for high-porosity hair, such as: 

3. Supplement protein treatments to reinforce the cuticles whenever necessary. 

4. Rinse your hair with cold water to help the cuticles lay flat. 

5. When moisturizing high-porosity hair, it is paramount to incorporate deep conditioning treatments into your routine to keep it healthy. 

6. It is essential to be gentle when detangling hair since it tends to be more fragile. 

Hair Porosity Levels: Which One is Better? 

Porosity is an indication of how damaged your hair is. High porosity means more damage that causes the cuticle layer to be lifted or raised. Low porosity hair means the cuticle layer is lying flat and is healthy. It simply means different hair requires different products and routines. 

The point is not to try and change your porosity level but to know how to take care of the hair you have. Don’t be fooled by myths that one is better than the other. Get to know your unique texture and what it needs to thrive. No matter your hair type, it will flourish if you care for it.


References

1. Lee, Y.; Kim, Y.-D.; Pi, L.-q.; Lee, S. Y.; Hong, H.; Lee, W.-S., Comparison of hair shaft damage after chemical treatment in Asian, White European, and African hair. Int. J. Dermatol. 2013, n/a-n/a.

2. Jeong, M.-S.; Lee, C.-M.; Jeong, W.-J.; Kim, S.-J.; Lee, K.-Y., Significant damage of the skin and hair following hair bleaching. The Journal of Dermatology 2010, 37 (10), 882-887.

3. Scanavez, C.; Silveira, M.; Joekes, I., Human hair: color changes caused by daily care damages on ultra-structure. Colloid Surf. B-Biointerfaces 2003, 28 (1), 39-52.

4. Yuen, C.; Kan, C.; Cheng, S., Evaluation of keratin fibre damages. Fibers and Polymers 2007, 8 (4), 414-420.

5. Hessefort, Y. Z.; Holland, B. T.; Cloud, R. W., True porosity measurement of hair: a new way to study hair damage mechanisms. J. Cosmet. Sci. 2008, 59 (4), 303.

6. Syed, A. N.; Ayoub, H., Correlating porosity and tensile strength of chemically modified hair. Cosmetics and toiletries 2002, 117 (11), 57-64.

7. Neudahl, G. A., Proteins for conditioning hair and skin. In Conditioning Agents for Hair and Skin, Schueller, R.; Romanowski, P., Eds. Taylor & Francis: 1999; pp 139-166.

HI,I'M VERNA

I’m just a girl who transformed her severely damaged hair into healthy hair. I adore the simplicity of a simple hair care routine, the richness of diverse textures, and the joy of sharing my journey from the comfort of my space.

My mission? To empower others with the tools to restore, and maintain healthy hair, and celebrate the hair they were born with!

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