We all know that our curl pattern plays a big role in how our hair behaves and how we need to care for it, but while we may have heard the term “porosity” before, many of us don’t know all that much about it or what it means. As important as curl pattern is, hair porosity is just as important in determining how your hair behaves, how it reacts to different styling and care products, and what kind of care it needs. Keep reading to learn about what hair porosity is, how it affects the way that your hair behaves, how to determine the porosity of your hair, and how to best maintain and troubleshoot the various types of hair porosity.
Put simply, hair porosity is how porous – or absorbent – your hair is. How well your hair absorbs water in the shower, humidity from the air, and styling products all comes down to your hair’s porosity. Porosity also affects how well your hair retains what it absorbs, particularly moisture. Hair porosity is a spectrum, where air that is low porosity is less absorbent and hair that is high porosity is more absorbent.
Your hair is able to absorb and release moisture through the cuticle, the outermost layer of each strand. On a microscopic level, the cuticle is comprised of overlapping “scales”, somewhat like the shingles on a roof. These scales can raise or flatten in response to environmental factors, and the degree to which they do so is what determines your hair’s porosity. A cuticle that remains mostly closed in response to moisture results in low porosity hair, while a cuticle that readily opens to accept (and release) moisture results in high porosity hair.
Hair porosity is largely genetic, though there are factors that can affect and change your hair’s porosity over time. Things like heat, harsh chemicals, and UV rays can all damage your hair over time, increasing its porosity and damaging its ability to retain moisture, hold color, and absorb product.
You can easily determine your hair’s porosity at home using either one (or both) of these tests:
1. The Float Test – take a clean, freshly shampooed, product-free, and completely air-dried strand of hair. Fill a bowl with room temperature water, and place the strand in the middle. Leave for five minutes. If the strand of hair has remained floating on the surface, you have low porosity hair. If it has sunk to the bottom, you have high porosity hair. And if it’s somewhere in between, you have medium porosity hair.
2. The Slide Test – take a clean, freshly shampooed, product-free, and completely air-dried strand of hair. Using one hand to pull it taut, use your opposite hand to gently pinch the strand between your thumb and finger and run your fingers up along the length of the hair towards your scalp. A bumpy and resistant feel indicates an open cuticle, meaning you have high porosity hair. A smoother glide upwards with little resistance means low porosity hair.
Low porosity hair is great at retaining moisture, but not so good at absorbing it. For this reason, those with low porosity hair should focus on imparting moisture with products such as butters, oils, and rich hair masks. Due to its reluctance to absorb product, you will need to encourage your hair to absorb them using heat (a shower cap topped with a warm towel will do – you do not need to apply intense heat to encourage absorption). For styling, avoid products that are heavy and may end up just sitting on your hair, such as heavy leave-ins and styling butters. Instead, opt for lightweight products like gels and styling milks, preferably those containing humectants like glycerin or honey. Finally, low porosity hair has little to gain from protein treatments, and they may even leave the hair straw-like due to build up. Refrain from protein treatments, and avoid using products formulated with protein.
Medium porosity hair is, well, the happy medium of hair porosity. No fighting to impart moisture, and no fighting to retain it. Your hair will remain balanced for the most part, though it may occasionally need boosts of moisture and sometimes even protein. Start with bi-weekly moisturizing treatments such as a CG-friendly hair mask, and gauge from there whether your hair needs more or less frequent treatments. If you find your hair has a hard time retaining moisture in between treatments, consider supplementing with a very light protein treatment. Be careful with protein, however – it can cause buildup and leave your hair straw-like, which may require a clarifying shampoo to remove.
High porosity hair requires a bit more attention to encourage it to better absorb and retain moisture. Some people have naturally high porosity hair, but many people end up with high porosity hair due to cumulative damage. Especially for those with damaged hair, moisturizing treatments must be supplemented with fortifying protein treatments to allow your hair to hold onto the moisture. Use nourishing styling products like leave-in conditioners, layered with sealing oils like jojoba oil or even shea butter. Aloe Vera extract or gel can also help flatten the cuticle and even out the pH of your hair, and some curlies incorporate it into their styling routines and daily use products.