Taking This Porosity Test Could Change The Way You Care For Your Hair

"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links."

News flash: There’s a method cosmetic chemists and beauty scientists regularly use to solve dryness, frizz, and damage—and you can use it at home. Knowing your hair’s porosity (something that’s frequently discussed within the textured-hair community on message boards and subreddits) can reveal a lot about your hair, like why you may be prone to flyaways or what the best products are for the style you want.

Essentially, porosity describes your hair’s relationship to water, and it can range from low to high.. “How much water your hair holds and how long it takes for it to dry is the simplest way to understand porosity,” says Felicia Leatherwood, a celebrity stylist who works with Issa Rae and Ava DuVernay. Read on for a professional strand plan.

What Is Hair Porosity

How can one head of hair appear dehydrated and crispy after sucking up half a jar of conditioner, while a different set of strands takes a full day to dry? Porosity explains it all. It’s determined by the position (and condition) of your hair strand’s protective exterior, called the cuticle layer. “Cuticles are meant to overlap to keep the moisture in and protect the inner cortex from heat and the environment,” says Corey L. Hartman, MD, a dermatologist in Birmingham, Alabama.

In high-porosity hair, the cuticle scales are open and lifted, exposing tiny holes and crevices along the strand. Highly porous hair is super permeable; it absorbs moisture like a sponge and releases it just as quickly, says David Adams, a trichologist and co-owner of Fourteenjay Salon. This leaves hair dry, weaker, and more vulnerable to damage and frizz. And in low porosity? The cuticle tends to be tighter and flatter, so hydration has a harder time escaping. That’s an advantage as far as strength and moisture go, but a densely packed cuticle also makes hair more resistant to products, so ingredients can build up rather than penetrate and do their job.

Do You Have High or Low Porosity Hair?

Going by texture alone won’t cut it. Scientists use diagnostic tools to determine porosity; you can rely on these DIY tests.

[accordion id='1df42545-40cb-44c8-99cb-5df49dfdb9e3'][/accordion]

▸If you said mostly As Your hair is probably low porosity.
▸If you said mostly Bs Your hair is probably high porosity.

What Affects Hair Porosity

The same genetics that gifted your hair its gorgeous natural texture also contributes to its porosity. But unlike hair texture, porosity isn’t easily identifiable. Wavy and curly tend to have more porosity than straight, Leatherwood points out, but not always. “All hair types have the ability to be either low or high porosity,” says Erica Douglas, a cosmetic chemist in Chicago and founder of Sister Scientist. “You really need to see how hair responds to water to determine its porosity.” (See “Are You High or Low?” at left to figure out yours.)

How you nurture your hair plays a big part too. Chemical processing (like hair color or relaxer) and daily styling (from heat, or friction from brushing your hair) chip away at the structure. “When you damage the cuticle layer, you’re putting holes and abrasions on the surface of the hair, which creates more crevices for water to enter and exit,” says Douglas. Wear and tear accumulate with length, so those #LongHairGoals compound porosity, especially at the ends. “Hair grows half an inch per month, so shoulder-length hair can have five to six years’ worth of damage,” Adams says.

And when it comes to the weather, it’s more like a TikTok influencer: The impact depends on your degree of exposure. Remember, porosity is also about how hair responds to moisture in the air. “The more humid the climate, the more moisture can penetrate the cuticle, causing it to swell or lift,” Douglas says. In drier environments, the cuticle layer is more closed or compact.” That explains why your hair can be completely different on a Vegas vacation than on a beachy getaway.

The Best Products For Your Hair's Porosity

“The biggest thing to know is that low or high porosity doesn’t determine good or bad hair,” Leatherwood says. “It’s all about understanding products and which ones work best for you.” Given that water opens your cuticle, your wash-day strategy can make or break your style. And the right stylers will keep hair looking fab the rest of the time.

A mild, sulfate-free shampoo followed by a rich conditioner with oils and butters helps to mitigate dryness in high-porosity hair. (Tip: If your current shampoo feels overly stripping, add some conditioner to transform it into a cleansing conditioner, suggests Leatherwood.) As for styling, you can infuse more moisture into high-porosity strands (and hang on to it longer) by layering leave-ins and stylers in the correct order. Apply a water-based product like a gel or mousse first, then seal with oil or a silicone-based serum. “Oil and water don’t mix, so you’re creating an invisible barrier that seals in moisture and keeps humidity out,” Douglas says. This advice works on all hair types, so the fine-haired shouldn’t feel they have to shy away from this strategy.

Meanwhile, low-porosity hair may require a shampoo with a higher pH, like a clarifying wash, to lift dirt, oil, and buildup that gets caught under the cuticle layer. Heat helps too. “Wrapping your hair with a silk scarf at night or using rollers with a deep conditioning mask once a month is one of the best things you can do to trap moisture inside the cuticle layers,” says Leatherwood, who also likes lightweight stylers like a mousse or cream-gel for low-porosity peeps. She also suggests drying hair with a diffuser instead of opting for wash-and-go styles. “If you leave the moisture in the hair all day, it’s going to weigh on it. A diffuser effectively removes the water without zapping all the hydration.” Balanced moisture and volume? Yes, please!

Products For Low And High Porosity Hair

The shampoo, conditioner, and styler for you.

Nutrient Blends Unbreakable Lengths Shampoo

Breakage, begone. Here’s a wash that gently removes dirt and oil to keep strands healthy and long.

Born To Repair Nourishing Conditioner

A blend of shea butter plus Amazonian nut and babassu extracts, this post-’poo locks in hydration.

F-Layer Deep Conditioning Serum

When you step out of the shower, saturate your strands in this nourishing serum. Your hair: glossy for days.

Peptide Prep Detox Shampoo

Hair with tightly packed cuticles needs a clarifying formula to really get in there and kick grime to the curb. This one is it.

The Deep Conditioning Concentrate

This mask-conditioner hybrid is a hydrating heavyweight. Aloe vera and pumpkin seed oil get the job done.

Zero Gravity Styling Mousse

A cloudlike foam that never leaves your hair feeling crunchy? Good. A styler that moisturizes with aloe juice? Grrrrrreat!

You Might Also Like

• Jennifer Garner Swears By This Retinol Eye Cream

• These New Kicks Will Help You Smash Your Cross-Training Goals