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Hair Porosity Matters — How To Test Yours With One Easy Trick

Image by Leandro Crespi / Stocksy
November 13, 2019

Like the skin, your hair has a unique structure that helps shape how you should care for it. Hair care is not one-size-fits-all. And yet, it tends to be oversimplified as far as routines go. Just think about how many skin care product categories there are versus hair care! But as with skin care, it's important to understand your own unique complexities and structure if you want treat it best. Well, one of the factors that massively affects your hair care and styling routine is porosity.

"Porosity has to do with your cuticle. Your cuticle is your outermost layer of hair; it's the protective layer of your strand," says hairstylist Levi Monarch. Not only is it protective, but it acts as the gatekeeper for moisture, determining when it flows in and out. The common visual comparison for the hair's cuticles is the shingles of a roof, says Monarch. However, these shingles raise and close due to external factors like humidity, styling, and chemical processing. When the cuticle is open, water more easily flows in—but on the flip side, water also evaporates easier. When the cuticle is dense and flat, moisture has a hard time penetrating the strand, but once it does, it stays.

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OK, so what does this mean IRL?

Hair porosity is a spectrum, ranging from high to low. It's good to know roughly where you fall on it, as it can determine how you care for and style your strands.

Hair that has high porosity means the cuticles are more open, so hair absorbs water easily. But as noted above, it also means it evaporates easily. If this is you, here are a few qualities that might give it away: After a shower, your hair dries very quickly. It also becomes dry and brittle easily, needing moisturizing agents between washes. And when you do apply products, your hair will "drink" it up. Hair that has high porosity also tends to frizz easier and has a more matte appearance.

Hair that has low porosity has dense cuticles. This means the hair has a harder time absorbing water, product, or even your scalp's natural oils, and you'll see buildup faster. It also takes longer to dry after getting wet as it's holding all that water in; you'll also find that this hair type doesn't deal with frizz as much since water in the air doesn't affect the cuticle as drastically.

Then you can fall somewhere between these two ends of the spectrum, which is considered medium porosity.

What's the "water test"?

After reading the above, you might have some ideas where you land on the spectrum. But if you need confirmation, this is the classic test to try. Grab a glass of water, and a strand of hair (like from your brush). Drop in the hair and see if it floats or sinks to the bottom. If it floats, you have low porosity hair. If it sinks to the bottom, you have high. If it stays somewhere in the middle, you're, well, somewhere in between.

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What does this mean for your own hair care and styling products?

Your hair porosity will have a pretty big influence on how you should treat your hair. Some of them likely seem like common sense, but let's dive in.

Low porosity hair has the fun task of opening up the cuticle to get moisture in. When you use conditioning treatments, heat and steam are going to be your friends. Try a hot oil treatment, or use a hair mask in a warm, humid environment, like a sauna, hot yoga class, or shower. After the shower, "if you want to use a leave-in, apply when it's slightly damp and the cuticles still open and more ready to absorb product," says Monarch. But don't overload hair with products, especially thick creams or oils, as they're not going to absorb and will end up sitting atop the hair. And since even your natural oils can cause a bit of buildup, scalp care is going to be important here, notes Monarch: Make sure to properly wash your hair regularly as excess oil and product can cause inflammation.

High porosity hair needs moisture, moisture, moisture. Apply hydrating products often. You can use a mask at least weekly, says Monarch; even consider applying on dry hair, pre-shower so your strands absorb more. Then after the shower, you'll want to seal that cuticle as quickly as possible: Try an apple cider vinegar rinse or just a shot of cold water will do. And then use a leave-in product, like an oil or serum, to seal in water. You can even use these between washing sessions: You'll find your hair will absorb this all rather quickly. And finally, whenever you use a hot tool, you need to use a protectant: Since the cuticles are raised naturally, they can damage easier.

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Alexandra Engler
Alexandra Engler
mbg Beauty Director

Alexandra Engler is the beauty director at mindbodygreen and host of the beauty podcast Clean Beauty School. Previously, she's held beauty roles at Harper's Bazaar, Marie Claire, SELF, and Cosmopolitan; her byline has appeared in Esquire, Sports Illustrated, and In her current role, she covers all the latest trends in the clean and natural beauty space, as well as lifestyle topics, such as travel. She received her journalism degree from Marquette University, graduating first in the department. She lives in Brooklyn, New York.