What is porosity? How do I determine my porosity? Why does it matter? If my hair is damaged, does that mean it’s automatically high porosity? Read on to learn more.
The first thing to know is your hair’s structure. Everyone’s hair has a medulla at the center, a cortex around the medulla, and a protective cuticle layer around the cortex. Porosity refers to how tightly overlapped the cuticle layer is on each hair. You can have more than one porosity type on your head, however, most people find the majority of their hair exists somewhere on the spectrum of high, medium, or low porosity hair.
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Hair Porosity Types
While porosity is more of a spectrum, there are typically three porosity types people discuss: low, medium (or “normal”) and high porosity. Knowing your porosity is important because it can tell you a lot about how your hair behaves: how quickly it gets wet, how easily it absorbs products, and how well it responds to certain ingredients.
Low Porosity
Low porosity hair has a tightly sealed cuticle layer, which makes it highly reflective and a stubborn defender of your cortex. Low porosity hair, therefore, appears naturally shiny. Because of the tight cuticle, low porosity hair naturally repels water, oils, and other outsiders, which makes it difficult to get wet and to absorb moisture. Once wet, low porosity hair may take longer to dry, because it also traps water molecules within it. Products tend to build up very easily on low porosity hair, so keeping it clean is a must! Low porosity hair can be more resistant to styling and manipulation, especially if the hair is coarse.
Medium Porosity
Medium porosity exists in the middle of the spectrum between low and high porosity hair. It accepts water and products with relative ease, dries fairly quickly, and is generally low-maintenance. Medium porosity hair is also relatively easy to dye and to manipulate into different styles. However, medium porosity hair tends to be more delicate than low porosity hair.
High Porosity
High porosity hair has an open cuticle layer, which means it tends to appear rougher and less shiny, and it accepts and absorbs water and products easily. High porosity hair will get wet quickly, but depending on density, can take a very long time to dry. The flared-open cuticle layer means high porosity hair is more fragile, and requires more maintenance than medium or low porosity hair. Hair that is high porosity can accept large amounts of products, which means it can take longer and cost more over time to style. Lightening and coloring high porosity hair is easy, but it runs a higher risk of getting damaged.
So what about damage?
Damage can occur at any porosity level, and depending on the type and extent of damage, it may change the hair’s porosity. Three signs of damage are to the left. First, cuticle scales may lift, or in extreme cases become removed, especially when exposed to peroxide, lye, and ammonia, which are common ingredients in hair dye, perms, and relaxers. These types of chemical services may permanently change your hair’s porosity. Cracks may occur along the cuticle, especially when hair is exposed to extreme temperatures and drying environments, including sun and heat damage. Chipped cuticle scales may occur when hair is exposed to frequent chemical services, heat, and friction. All three types of damage can contribute to dullness and frizz.
What might damage look like with my hair’s natural porosity?
Interestingly enough, I could not find any good, magnified comparisons of different porosities at different damage levels. So, I did what any novice would do and tried to digitally create a visual for what some minimal damage might do to different porosity levels. This includes chipping, slightly raised cuticles, and perpendicular cracks. The photo quality is not great, I encourage you not to zoom in, but it’s suitable for demonstration. For more extensive damage, scroll down.
How much damage is too much damage?
A great question, and one you should consider before doing anything potentially harmful to your hair. If you’re worried about damage, I advise you to consult a neighborhood (licensed) hair stylist who can take a look at the condition of your hair. Severely damaged hair will not be able to maintain its structural integrity; it may appear fuzzy and fluffy, it may stretch extremely far when brushed, and may break very easily.
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