Frizzy, poofy, or smooth: How your hair looks on any given day comes down to a few things, including your hair’s porosity. Put simply, porosity refers to how much moisture your hair is able to absorb and retain. It’s often discussed in regards to curls, but understanding your hair’s porosity—and what that means for your haircare routine—can be useful for everyone, including those with straight, sleek strands.

To help better explain hair porosity, we consulted expert hairstylist Dhiran Mistry. Ahead, Mistry breaks down the differences between high porosity hair and low porosity hair and reveals how to conduct a hair porosity test at home. You’ll also learn a bit about what habits can influence your hair’s porosity and discover some of Mistry’s best haircare tips for a healthy-looking mane. Find all the details, ahead.

What Is Hair Porosity, Exactly?

According to Mistry, the amount of moisture your hair can absorb determines how porous it is. High porosity hair refers to hair that can absorb a lot of moisture but can’t retain it very effectively. Low porosity hair, on the other hand, holds moisture well but absorbs very little. In between high and low porosity hair is medium porosity hair, which we like to think of as the goldilocks zone: It can absorb and retain moisture, but it’s not overly porous. As for why your hair’s porosity matters, it’s pretty simple. How much moisture your hair holds—and how well—plays a huge role in determining your hair’s overall appearance. Generally speaking, the more moisturized, the sleeker, smoother, and shinier your hair will be.

What Does High Porosity Hair Look Like?

According to Mistry, if you have high porosity hair, you may find “you struggle to make it look healthy.” Overly porous hair may appear rough and frizzy and often has a “matte, dull [appearance].” High-porosity hair may also be more prone to tangling, which can lead to breakage. And though it’s not exclusive to people with curly or natural hair, Mistry says that those with curls and natural hair are more likely to have high porosity hair than those with straight strands.

What Does Low Porosity Hair Look Like?

Medium and low porosity hair tends to be shinier, sleeker, and smoother than high porosity hair. It’s generally regarded as healthier-looking than high-porosity hair. However, with a lesser ability to absorb moisture, low-porosity hair may easily get weighed down by heavier haircare products, like leave-in treatments and styling aids.

What Can Make Your Hair Overly Porous?

Sometimes, having porous hair is unavoidable—as we mentioned earlier, it’s often connected to your hair’s texture (which is determined by genetics). That being said, there are external factors that can influence your hair’s porosity, too. Mistry says that frequent exposure to excessive heat and chemical processing (such as bleaching) are among the most common risk factors for damaged, highly porous hair. That isn’t to say that hot tools and hair dye should be off-limits—but if you do plan on using heat regularly or color-treating your hair, you want to be sure you’re caring for your strands properly.

How To Test Hair Porosity At Home

If you’re unsure where your hair falls on the porosity spectrum, you’re not alone. Thankfully, it’s pretty easy to find out for yourself at home with a high or low porosity hair test. Here’s how to do it:

First, wash your hair as usual and let your hair air-dry—but don’t put any products in it. Once your strands are bone dry, pluck a hair from the roots and place it into a glass of water. Then, watch what it does. “High porosity hair will sink” immediately after you place it into the water, Mistry says, whereas low porosity hair “will float” on the surface of the water. If your hair floats briefly, then sinks, or hovers in the middle of the glass but doesn’t completely sink, you likely have medium porosity hair. Another way to test your hair’s porosity is by getting it wet and seeing how long it takes to dry. The quicker it dries, Mistry says, the more porous your hair is likely to be.

How To Care For High Porosity Hair

High porosity hair, generally speaking, requires a bit more maintenance to look and feel its best than lower porosity hair types. That’s because your hair needs moisture—without it, it’ll feel dry, rough, and brittle and be much more vulnerable to damaging stressors. Ahead, learn five tips to keep in mind when caring for high porosity hair.

1. Switch To a Hydrating Shampoo and Conditioner

The shampoo you use can play a huge role in how your hair looks and feels, and this is especially true of those with high porosity hair. Ideally, you want to reach for a mild shampoo that cleanses without over-drying your hair, such as Amino Acid Shampoo. This Kiehl’s favorite is made with coconut oil and amino acids and cleanses while helping to add body and shine. Pair it with Amino Acid Conditioner to help maintain your hair’s natural moisture balance for strong, shiny strands.

If your hair is extremely parched, try Nourishing Olive Fruit Oil Shampoo and Nourishing Olive Fruit Oil Conditioner instead. The moisturizing duo with avocado oil and olive fruit oil instantly moisturizes dry hair, leaving your strands feeling soft, supple, and more manageable.

2. Incorporate Hair Masks Into Your Routine

“You definitely want a deeper conditioner” if you have highly porous hair, Mistry says. Look for something “that sits heavier on the hair,” such as a hair mask. Our pick: Olive Fruit Oil Deeply Reparative Hair Mask. This rich, creamy deep conditioner is formulated with a blend of oils, including olive fruit oil, avocado oil, and vitamin C-packed lemon oil. It moisturizes and helps strengthen hair that’s been weakened by exposure to stressors like chemicals, heat, and sunlight. When used consistently, it also helps prevent future damage from external aggressors. The moisturizing mask is best suited for dry, frizzy, and damaged hair, and it can be used weekly or as needed to help strengthen and nourish your strands.

3. Get Your Hair Trimmed Regularly

When dealing with high porosity hair, Mistry says, “you want to keep on top of your regular trims.” High porosity hair may be more brittle and prone to breakage, he says, and “the more damaged [and] dry it gets, the worse it’s going to get.” How often you need to get a trim depends on your hair length and texture, but generally speaking, you want to aim to get a trim once every six to eight weeks. If you’re not sure exactly how long you can go between trims, ask your hairstylist next time you pop in for an appointment—they’re there to help you figure out what your hair needs to look and feel its best.

4. Invest In Moisturizing Leave-In Products

Leave-in conditioners and styling aids won’t help repair your hair in the long term—only time can do that—but they may help prevent porous hair from absorbing too much moisture. If your hair is prone to frizz, we recommend adding a leave-in treatment, such as Smoothing Oil-Infused Leave-In Concentrate, to your daily haircare routine. Made with fairly-traded argan oil and babassu oil, this unique hair treatment nourishes and smooths dry, frizzy hair without weighing it down. It also penetrates the hair fiber to help fortify hair and make it more resistant to further damage. Apply a small amount to damp or dry hair and style as usual for shinier, healthier-looking strands.

5. Avoid Heat and Chemicals When Possible

Lastly, since external stressors like heat and chemical processing can increase your hair’s porosity, you want to make an effort to avoid those stressors whenever possible. Allow your hair to air-dry when you can, and keep your use of hot tools to a minimum. If you do need to use hot tools, try prepping your strands with a heat protectant to help shield your hair from unnecessary damage.

How To Care For Low Porosity Hair

As we mentioned, lower-porosity hair is capable of retaining moisture and, as such, doesn’t require quite as much maintenance. To help keep your strands looking and feeling their best, we recommend incorporating a lightweight hair oil into your regular haircare routine. Note that lightweight is the key here: Since your hair doesn’t absorb moisture as readily, anything too heavy can sit on the hair shaft and weigh it down.

Next: Try Our 5 Tips To Restore Your Damaged Hair