Most hair care guides and even many professionals rarely discuss hair porosity. You’re unlikely to hear your stylist explain how to choose products based on porosity, yet it plays a critical role in hair health. That’s because porosity is rooted in science—and this guide will break it down for you.
Hair porosity describes how your hair absorbs and retains moisture, which is determined by the size, volume, and density of pores along the hair shaft. All hair is porous, but there are three levels: low, medium, and high. Knowing your type can help you choose the right products and build a more effective routine.
I am fortunate to 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
Hair porosity is a common concern for both consumers and hair care experts. Excessive grooming techniques or harsh chemical treatments can push hair beyond its limits, causing protein loss and leaving the shaft more porous over time.
But what exactly is porosity? In simple terms, hair porosity describes the hair’s condition at both a visible and microscopic level. The word ‘porosity’ comes from ‘pore’ and refers to the size, volume, and density of the pores along the hair shaft.
Cuticles are the outermost 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.
All hair is porous, but the degree of porosity reveals how healthy or damaged it is. Higher porosity usually signals more damage, while lower porosity often means the cuticle is intact. Chemical treatments, UV exposure, and excessive or harsh brushing are all factors that can lift and weaken the hair cuticle, increasing porosity over time.
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.
Hair Porosity: The Key to Choosing the Right Products
Hair care isn’t one-size-fits-all; every texture needs special attention. The secret to choosing the right products is knowing your hair porosity. Porosity reveals how well your hair absorbs and holds moisture. Low porosity hair needs lightweight products and deep conditioning with heat, while high porosity hair requires sealing and extra protection.
Ignoring porosity can lead to dryness, dullness, frizz, and breakage. By understanding your porosity level, you can build a routine that keeps your curls healthy, shiny, and strong.
Different Hair Porosity Types and Causes
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 lie 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
When hair becomes damaged, tiny cracks form in its protein structure, eventually creating pores along the strand. These changes are visible signs that the hair has been compromised.
Porous hair often shows several telltale characteristics:
- A rough texture you can feel when running your fingers through it.
- Rapid absorption of moisture followed by quick drying.
- Persistent frizz that’s difficult to manage.
- Challenges with combing, styling, and overall manageability.
- A fluffy or poofy appearance.
- Enlarged pores within the strands caused by protein loss, leaving empty spaces in the hair shaft.1,2,3
- Raised, broken, or even missing cuticles that let water in easily but release it just as quickly. This makes it difficult to maintain moisture, leaving hair dry, brittle, and prone to breakage.
When damage becomes severe, the inner cortex of the hair can be exposed to the environment. If the cuticle is completely gone and the strand is too compromised to protect, the hair is considered degraded.
Degraded strands lack attached cuticles, making them fragile and prone to excessive breakage and shedding. Once hair reaches this stage of porosity, the only solution is to trim away the damaged ends and allow healthy growth to take its place.
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.
Hair Porosity Test
A simple hair porosity test (like the float test) can help you clearly identify if you have low, medium, or high porosity hair so you can choose the right products and routine.
Hair scientists, however, use high-tech experimental methods to measure porosity with precision. These tests analyze individual hair fibers to calculate a numerical value that reflects porosity levels.4,5,6
Since consumers don’t have access to this kind of specialized equipment, we rely on more practical approaches. Hair experts have created a variety of simple at-home and salon tests that make it easy to assess porosity without advanced tools.
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 can have different porosity levels from the roots to the ends, which makes it challenging to determine an exact overall level. The float test cannot capture this variation. In most cases, the ends of your hair are more porous because of natural wear, styling, and environmental damage, while the new growth near the roots typically has lower porosity.
Characteristics of Different Porosity Levels
You can still make a fairly accurate guess about your porosity type. Each level of hair porosity has unique traits that can be identified through specific characteristics.
| Low Porosity | Medium Porosity | High 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 behaves as normal during hair coloring and color appears uniform. | Low to moderate roughness. | Extremely rough and dry. |
| Hair feels good and only shows roughness toward the ends of the hair. | Moderate response to high humidity conditions. | High uptake of moisture from its surroundings. |
| Hair behaves 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?
Yes, hair porosity levels can change. Hair may shift from low to high porosity—or the reverse—depending on internal and external factors. These changes often occur gradually but can also be triggered by chemical treatments, frequent heat styling, or exposure to environmental stressors like sun, wind, and humidity. Let’s explore how porosity shifts happen and the science behind their impact on your hair.
An Increase in Hair Porosity Level: Low to High
Low-porosity hair is typically virgin hair that has not been chemically treated. When exposed to harsh processes such as bleaching or permanent dyeing, the hair’s proteins become stripped away, causing significant damage and raising its porosity level.
During these oxidation processes, the proteins in the hair react, and the amino acids break down. The resulting byproducts dissolve in water and are washed out during regular shampooing.
As proteins and cuticles are lost, the pores along the hair shaft grow larger and more numerous. Over time, low-porosity hair transitions into high-porosity hair. This is why frequent bleaching or coloring often leaves hair feeling rough, fragile, and harder to manage, because low-porosity hair has shifted into high-porosity hair.
A Decrease in Hair Porosity Level: High to Medium
With consistent care, high-porosity hair can improve and shift closer to a medium level. When that happens, strands regain strength, shine, and a healthier overall appearance.
This process requires repeated use of hydrating, conditioning, and fiber-strengthening formulas. Treatments containing vegetable proteins, keratin, and micro-polymers help rebuild the hair shaft. Research shows that proteins can restore mechanical strength and bring back natural gloss, 7 while cationic conditioning polymers improve fiber quality and reduce excess porosity.
By following a regular regimen, you can gradually decrease porosity levels. My own hair is proof: years of flat ironing, bleaching, and chemical treatments left me with severe damage and high porosity. After incorporating targeted treatments, I was able to bring my porosity back under control (as shown in the before-and-after photos below).
Some of the treatments I used include:
How to Improve and Manage Your Hair Porosity
Now that you know hair porosity can be improved with the right care, you can adjust it to meet your needs. Your curl pattern, whether tighter coils, loose curls, or waves, interacts with porosity. Two people may both have high porosity, but their curl pattern will influence how frizz appears, how quickly hair dries, and which products work best.
Tips for Low-Porosity Hair
Many people are tempted to layer multiple products to moisturize low-porosity hair, but that approach often backfires. Because the cuticles are tightly packed, low porosity hair struggles to absorb heavy formulas, leading to buildup instead of lasting hydration.
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. Look for shampoos, conditioners, deep conditioners, leave-ins, and curl creams specifically formulated for low porosity curly hair products — lightweight formulas that penetrate without weighing curls down.
3. Don’t avoid protein. Many people either shy away from it or aren’t sure which type to use, but when applied in the right balance, protein strengthens the hair, smooths the cuticle, and helps prevent breakage.
4. Boost the power of your deep conditioner by adding heat. Using a steamer or gentle heat lifts the cuticles, allowing your hair to fully absorb moisture and nutrients.
Tips for High Porosity Hair
Unlike low porosity hair, high porosity hair can absorb multiple layers of product, which makes it easier to load up on nourishment and moisture. The key is balance; blending protein-rich and moisturizing products will give you the best results.
Look for products specifically formulated for high porosity hair, including:
- Shampoos
- Leave-in
- Oils and butter
- Deep conditioners
- Additional tips to protect and strengthen high porosity hair:
- Supplement with protein treatments to reinforce the cuticle when needed.
- Rinse with cold water after conditioning to help the cuticles lie flat.
- Incorporate regular deep conditioning treatments to keep moisture locked in.
- Handle hair gently to prevent further cuticle damage
To keep high porosity hair strong and manageable:
- Detangle gently to avoid breakage, since high porosity strands are more fragile.
- Supplement with protein treatments to reinforce the cuticles whenever needed.
- Rinse with cold water after conditioning to help the cuticles lie flat.
- Incorporate regular deep conditioning treatments to maintain hydration.
Hair Porosity Levels: Is One Better Than the Other?
Porosity reflects the condition of your hair’s cuticle layer. High porosity usually signals more damage, with cuticles that are lifted or raised, while low porosity means the cuticle lies flat and is generally healthier. Neither type is inherently better—it simply means your hair will respond differently to products and routines.
The goal isn’t to change your porosity level but to learn how to care for the hair you have. Don’t be misled by myths that one level is superior. Instead, focus on understanding your unique texture and giving it what it needs to thrive. With the right care, any porosity level can support healthy, beautiful hair.
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.
