I love, love, love my curly hair—like, take-a-million-selfies, write-a-poem kind of love. The curlicues that pop up on my forehead, the ringlets sandwiched next to each ear, the whole shebang. But that wasn’t always the case. No, just a few years ago, I was the girl who got fed up and began flat-ironing her curls—*insert tear emoji*—after years of trying (and failing) to find a curl routine that would give me the hair of my dreams.
No matter what products I loaded on my 3a curls, they always felt too frizzy, too big, too dry, and too...wrong. I felt like I was missing something, some crucial secret step that all my curl sisters had somehow learned. And after stumbling upon a curly-hair guru on Instagram, I found out I actually was. Because a very important thing called “hair porosity” exists, and it’s been the key to fixing virtually all my curl issues.
Now, my camera roll is filled with hair selfies and my straightener is collecting dust. And to help you get on my level of happiness and find out if porosity is the answer to all your (curl) problems—which, TBH, it definitely could be—I’ve broken down everything you need to know to figure out what the heck your hair wants from you.
What is hair porosity?
In the most basic of basic explanations, porosity is your hair’s ability to absorb and retain hydration, says Mezei Jefferson, assistant vice president of education at L’Oréal USA. Your hair strand might look like one single, smooth strip, but it’s actually made up of multiple layers (called cuticles) that determine how much water and ingredients can actually penetrate the hair strand—kind of like a protective seal.
If your cuticles are really close together (aka low porosity), they’ll basically repel water and products, making it harder to hydrate and treat your curls. On the flip side, if your cuticles are super raised and open (aka high porosity), they’ll lose moisture fast, leaving your curls perpetually dry and fuzzy. Basically, your porosity determines what the hell your hair needs and what it most definitely doesn’t.
My curls, for example, were always dry and fluffy, no matter how many moisturizing products I layered on. The reason? My cuticles were apparently raised (highly porous). Once I switched up my hair routine and started listening to what my curls needed, I finally got the results I wanted: frizz-free and hydrated hair.
How do you test your hair porosity?
If you don’t have a microscope and a medical degree on hand, your best bet at figuring out your hair’s porosity is with the float test. According to Deanna Brown, hairstylist and educator at DevaCurl, all you need to do is take one dry, clean, oil-free piece of hair (just gently finger-comb your clean hair until one inevitably sheds), drop it in a glass of room-temperature water, and let it sit for five minutes.
- If the hair floats and doesn’t sink, it means the hair has low porosity.
- If the hair sinks slowly, it means the hair has medium/“normal” porosity.
- If the hair sinks quickly, it means the hair has high porosity.
Of course, as with any completely uncontrolled, unscientific experiment, results may vary wildly, especially if you have any product or oils on your hair (which could cause it to automatically float or sink).
So if you’re skeptical, see which of these categories sounds most like your hair:
➰ Low-Porosity Hair
Your cuticles are tight on the hair shaft, i.e., super close together, preventing water and moisturizers from penetrating your hair. So you’ve probably noticed that:
- products tend to sit on top of your curls and either weigh them down or leave them with buildup.
- low volume and limp curls are regular occurrences.
- your hair takes a minute to absorb water and get fully saturated in the shower.
- your curls can take a longer time to dry completely.
➰ Medium/“Normal”-Porosity Hair
Your hair cuticles open and close easily enough to allow hydration in and out, which means that:
- your curls tend to be healthy, shiny, and voluminous without requiring a ton of product.
- your hair doesn’t get fluffy or visibly dried out by the end of the day.
- your curls are pretty easy to style—they don’t get greasy too easily or dry too easily.
➰ High-Porosity Hair
If your cuticle is perpetually open and lifted (often the case if you color or chemically treat your hair), it both absorbs and loses moisture quickly, meaning that:
- your hair usually looks dull and feels dry after a few hours, no matter what products you use.
- your curls are prone to tangles, knots, and breakage.
- your hair can soak up oils and conditioners without getting weighed down or greasy.
- frizz is the basic MO of your hair, regardless of what products you layer on.
What causes low or high porosity?
In most cases, porosity is genetic, but it can also be affected—and completely altered external factors. “Daily heat styling, pool water, pH imbalances, chemical and color treatments, and overexposure to the sun can all cause high porosity,” says curly-hair guru Verna Meachum. After talking with Meachum and Brown about my curls, it was easy to see that my overly porous hair probably had something to do with the fact that I straightened it every day for six years and used chemicals to fight the frizz, essentially stripping my hair cuticle. Oops.
As for low-porosity hair, Brown says one of the most common causes outside of genetics is product buildup. Silicones, heavy oils, and rich butters can create a moisture-repelling barrier on your strands, leading you to believe you have low porosity when you might, in fact, have “normal” porosity.
Can you change your hair’s porosity?
Yes and no. If product buildup is secretly causing your low-porosity hair, washing with a clarifying shampoo can bring your hair back to its natural medium porosity. But if your porosity has been caused by damage or genetics, there’s not much you can do to change it, says Jefferson. But don’t freak—no matter what type of hair you have, it is neither good nor bad. It’s all about how you choose to take care of it. Which brings us to...
The Best Routine for Your Porosity Type
Yep, there’s a routine for everything when it comes to curly hair. Thankfully, all these curl products and tools should overlap with your usual routine (no crazy products here), so this shouldn’t be too painful of a change.
If You Have Low-Porosity Hair...
Because the cuticles of low-porosity hair are so tightly closed, products tend to build up on strands rather than infiltrate them. And all that residue from your shampoos, conditioners, and stylers ends up creating a barrier that prevents water from getting into your hair, leading to dryness. So your main goals are to infuse your strands with moisture while avoiding anything that can cause even more product buildup. How? Use lightweight formulas, a weekly clarifying shampoo to remove residue, and indirect heat or steam treatments to help open up those tight cuticles.
If You Have Medium-Porosity Hair...
Those with medium-porosity hair have no real restrictions (lucky you). But to get the best, healthiest curls, you should focus on maintaining an already balanced ratio of daily moisturizers (like creams and mild cleansers) to weekly hair-strengtheners (like protein-filled masks), according to Meachum. And go easy on the heat treatments and coloring or you’ll shift your hair into the high-porosity category.
If You Have High-Porosity Hair...
Highly porous hair absorbs a ton of water when wet but basically loses it all as it dries, leaving it perpetually dry, weak, and prone to damage. So your routine should be geared toward ultra-moisturizing cleansing conditioners and leave-in conditioners (to hydrate), protein-packed deep conditioners (to strengthen the cuticle), and, if you want curl definition, a gel or styler (to lock in all the moisture).
Boom—easy, right? You may now go forth with your new, bouncy, perfectly compliant curls and never have a bad hair day again. Hopefully.
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