How to Determine the Porosity of Your Hair

And yes, it matters.

By Brittany Burhop Fallon, Beauty Director · Published: Jul 4, 2023

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This article first appeared in the Summer 2023 issue of New Beauty. Click here to subscribe

A deep-dive into the porosity of our hair: What it is, the different types, and how it impacts the products we use to wash, style and treat.

What is hair porosity?

“Porosity is a measurement of the hair’s ability to absorb and hold moisture,” explains celebrity colorist Rita Hazan. “It can also be described as the indicator of how easily moisture can penetrate the hair.” Shab Caspara, trichologist and founder of Leona, a new personalized hair-care platform, compares porous hair to a marble countertop that absorbs whatever liquid you pour onto it. “On the other hand, low-porosity hair, which is the healthiest hair with its cuticles intact, protects the hair and limits excessive absorption of water or foreign ingredients. Think of it like a sealed marble countertop versus one that is raw, untreated stone.”

According to Anabel Kingsley, trichologist and president of Philip Kingsley, coarse and coiled hair textures tend to be more porous than fine-to-medium textures. “Porosity is genetic, but it can also be affected by external factors, like coloring your hair or heat-styling it,” Hazan adds. “Hair color increases porosity because it has to penetrate the cortex— the central layer of the hair shaft—making it harder for the hair to retain moisture in the future. This is why dryness can become an issue with high-lift color or bleaching.”

The 3 Types

There are significant differences between low-, medium- and high-porosity hair, as well as different ways to properly take care of each one. “Knowing your porosity is essential in understanding how to care for your hair,” says Sharley Butcher, textured hair specialist and global brand ambassador for Curlsmith. “Once this is determined, you will achieve better results from your hair-care routine.”

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Low-Porosity Hair

What it’s like: “Low-porosity hair is usually easier to care for and requires less maintenance than other hair textures,” Kingsley explains. “The cuticle scales, which form the outer layer of the hair, tend to overlap. Because there is limited space between the scales, it makes it harder for water, as well as products like oils and conditioners, to penetrate and deliver moisture to the hair shaft.” Other signs pointing to low-porosity include hair that is susceptible to buildup, hair that gets easily weighed down by product, and hair that takes a long time to get wet, and to dry. However, despite those attributes, hair in this category tends to look and feel healthy and strong.

How to take care of it: “Opt for lighter-weight conditioners and styling products instead of heavier ones that may sit on the hair shaft and cause buildup,” says Kingsley, who suggests Philip Kingsley’s cult-classic Elasticizer ($31) hair mask, which is water-based rather than oil-based. “You can also cover your hair with a towel or shower cap to trap heat when you’re deep-conditioning to help the treatment absorb better.”

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Medium-Porosity Hair

What it’s like: According to Hazan, medium-porosity hair tends to be well-balanced in terms of moisture absorption and retention, but may occasionally look dull. “You may have this type if your hair is easy to style and can hold styles for a good length of time, takes color well, and doesn’t take too long to air-dry,” she explains.

How to take care of it: “Regular hydration and products with nourishing ingredients help keep medium-porosity hair healthy,” Hazan says. “Gentle products that protect your hair from environmental damage, including pollution and UV rays, can help you maintain a balanced, normal porosity.” We like Iles Formula Haute Performance Shampoo ($42) and Conditioner ($52), which are free of sulfates and silicones, made with yacon root juice that helps keep the porosity of the hair even, and won’t create buildup.

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High-Porosity Hair

What it’s like: This hair type has a wide-open cuticle structure, dries fast and breaks easily. “Frizz and dryness are indications of high porosity,” says Iles. “Chemical treatments such as bleach and straightening treatments are often a leading cause of high porosity.” Moisture absorbs quickly, but the hair has trouble retaining it. “When washing your hair, it may take a lot of water before your hair is fully wet,” adds Kingsley. “Coarse, curly and coiled hair textures are high-porosity—they drink up and require lots of moisture.”

How to take care of it: Use moisturizing products, like those made with rich oils and/or butters (you may need several to achieve your hair’s optimal look and feel). “Protein fillers like bond-builders are essential, as they are designed to repair porosity by strengthening the protein structures and allowing the protective cuticle layers to remain closed,” says Caspara. “This increases shine and decreases frizz. They are also a great pre-treatment to chemical coloring services, which can weaken the hair.” Butcher recommends Curlsmith Bond Curl Rehab Salve ($30), which she describes as “an intense pre-shampoo treatment that targets all three hair bonds to repair and strengthen hair.”

Inside Tip:
Although bondbuilders can help decrease hair porosity, Caspara urges not to use these products more than once a week. “If used too frequently, they will have an opposite effect and slowly build up and dry out the hair.”

How to Test Your Hair Porosity

Two ways to discover the porosity of your hair at home (a professional stylist can also help).

DO THE FLOAT TEST.

Fill a glass three-fourths full of room-temperature water, place a strand of your clean hair in the water and let it sit for a minute. “If the hair sinks slowly, it has medium, or normal, porosity,” says Wendy Iles, celebrity hairstylist and founder of Iles Formula. “If it sinks immediately, it has high porosity. If it floats on top of the water, it’s an indication of low porosity.”

CLOCK YOUR DRY TIME.

“See how long it takes for your hair to air-dry,” Caspara says. “Healthy hair tends to dry much faster than porous hair, which can take hours due to its weakened cuticles that continue to hold water.”