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You may have heard the term “hair porosity” and wondered what it means. Essentially, hair porosity is about your hair’s ability to absorb and retain moisture.

The porosity of your hair affects how well oils and moisture pass in and out of the outermost layer of your hair, known as the cuticle.

Hair porosity is typically divided into three broad categories:

  • Low porosity: Cuticles that are close together.
  • Medium porosity: Cuticles that are less tightly bound.
  • High porosity: Cuticles that are more widely spaced.

This article will take a closer look at what affects the porosity of your hair, how you can figure out the type of porosity you have, and, depending on the hair porosity you have, how best to treat your hair.

To understand the concept of hair porosity, it helps to know a bit about the structure of your hair, which consists of three layers. These layers include:

  • The cuticle: This is the tough, protective outer layer of your hair that’s made up of smaller cuticles that overlap each other, similar to shingles on a roof.
  • The cortex: This is the thickest layer of your hair. It contains fibrous proteins and the pigment that gives your hair its color.
  • The medulla: This is the soft, central part of the hair shaft.

For your hair to stay healthy and hydrated, water, oils, and other moisturizing products need to be able to pass through the cuticle to get to the cortex.

But, if the cuticles are too close together, it’s not easy for water and oils to penetrate the hair. This can make it harder for your hair to get the moisture it needs.

Also, if the cuticles are too widely spaced, your hair will have a harder time retaining moisture and staying hydrated.

How your hair absorbs and retains moisture is largely due to genetics. So, if low porosity hair runs in your family, there’s a good chance you’ll have low porosity hair, too. But while genetics can affect porosity, it isn’t the only contributing factor.

Blow drying, bleaching, straightening, overwashing, and using harsh products can all damage your hair over time. This can cause your hair cuticles to become raised and open, which may make it harder for your hair to retain moisture.

In addition to hair treatments, too much ultraviolet exposure can also increase the porosity of your hair. To protect your hair from the sun, wear a hat or some type of head covering when you’re outdoors.

One of the easiest ways to test your hair porosity is by using a glass of water. Here’s how to do it:

  1. Shampoo and rinse your hair to remove any product buildup.
  2. Fill a glass with water.
  3. Once your hair is clean and dry, drop a single strand of your hair into the glass of water.
  4. Watch the strand to see if it sinks to the bottom of the glass or floats at the top.

The results

  • Low porosity: If the strand floats at the top before sinking, you likely have low porosity hair.
  • Normal porosity: If the strand floats somewhere in the middle of the glass, you probably have medium or normal porosity hair.
  • High porosity: If the strand quickly sinks to the bottom of the glass, you likely have high porosity hair.

You can also test your porosity level by running a finger down a strand of your hair. Low porosity hair will feel smooth, whereas high porosity hair will feel rough and bumpy because the cuticles are open.

With low porosity hair, the cuticles are tightly packed and very close together. This makes it harder for moisture to penetrate the hair shaft.

You may have low porosity hair if:

  • hair products tend to sit on your hair and don’t absorb easily
  • it’s hard for water to saturate your hair when washing
  • it takes a long time for your hair to air dry

With medium or normal porosity hair, the cuticles aren’t too close together, but aren’t too open either. This allows moisture to penetrate easily, and it also makes it easier to retain moisture for a longer period of time.

You may have medium porosity hair if:

  • your hair is easy to style and can hold styles for a good length of time
  • your hair takes color well
  • your hair tends to look healthy, shiny, or glossy
  • it doesn’t take too long for your hair to air dry

Heat damage and other chemical processes can cause normal porosity hair to change over time.

Whether due to genetics or hair damage, high porosity hair allows moisture to be absorbed into the hair shaft easily, yet it isn’t able to retain moisture for long. This is because the cuticles tend to have gaps or spaces between them.

You may have high porosity hair if:

  • water and other moisturizing products are quickly absorbed into your hair
  • your hair tends to break easily
  • your hair tends to be frizzy and dry
  • it doesn’t take much time for your hair to air dry

If you have high or low hair porosity due to genetics, you may not be able to change it. However, according to hair care experts, there are things you can do to make your hair healthier, more manageable, and easier to style.

For low porosity hair:

  • Use protein-free conditioners. These tend to be more easily absorbed into your hair and may be less likely to cause product buildup.
  • Apply conditioner to hair that’s already wet. Diluting the conditioner may make it easier to be absorbed into your hair.
  • Look for ingredients like glycerin and honey in shampoos and conditioners. Avoid products with oils, as these tend to have a harder time penetrating the cuticle.
  • Apply heat when you condition your hair. Use a steamer, heat cap, or hooded dryer. Or, if you don’t have those, put a shower cap over your hair once you’ve added a conditioner.

For high porosity hair:

  • Look for ingredients like butters and oils in shampoos and conditioners. These ingredients will help moisturize your hair.
  • Use leave-in conditioners and sealers. These products help your hair hold on to moisture.
  • Use a heat protectant product on your hair. Apply this product before you blow dry or use other heat styling treatments. This can protect your hair from heat damage.
  • Avoid hot water when shampooing and conditioning. Use lukewarm water instead.

Hair porosity may not be a term you hear often. But knowing what type of hair porosity you have can help you better understand how to manage, treat, and care for your hair. And that can lead to hair that’s stronger and healthier.