What is Porosity?
Porosity is the term used to describe how easily water and other matter can diffuse in and out if the cuticle and into or out of the cortex. It is determined by how tightly and thoroughly the cuticle scales adhere and overlap across the surface of the hair shaft. It is an important factor in maintaining the optimum levels of moisture in your hair, thereby preserving its softness and shine as well as its strength.
Levels of Porosity
Porosity can be classified under three levels or categories:
Low — Low porosity is characterized by a very tightly bound cuticle layer. The individual scales of the cuticle lie flat and thoroughly overlap each other. This hair usually has a high shine and is, overall, considerably healthy. With low porosity hair the cuticle scales are so tightly bound it can be difficult for water to penetrate, but once it does, that moisture is retained.
If your hair tends to repel water while wetting it and products feel like they sit on your hair, more than likely it has a low porosity. Because of its resistance to penetration, it is more difficult to use chemicals on (i.e. relaxers, color etc) and can be difficult to re-moisturize should it become dry. Low porosity hair is prone to excessive protein build-up and will have a straw-like feeling if deep treatments containing protein are used. Regular deep conditioning treatments coupled with mild heat, such as a steamer (or if a steamer isn’t in your budget, cover your hair with a shower cap or plastic bag and wrap it in a hot towel) will help with retaining moisture. Cleansing your hair with baking soda can also help raise the cuticles to allow moisture to penetrate the cuticle layer. Always apply products on damp hair since this type needs all the moisture it can get.
Normal — Normal porosity hair requires the least amount of maintenance and is able to resist the penetration of too much water, only allowing moisture to pass through as needed, but absorbs water well. It can absorb a maximum of 31.1% of water by weight, has a natural shine, and hold styles well. This level of porosity is ideal.
Normal porosity hair takes to chemicals fairly well, but is subject to change in porosity through mechanical, environmental, heat, and/or chemical damage. Regular protein treatments or products are not necessary in a regimen for this hair type, however, the occasional protein treatment will benefit it.
High — High porosity is an unfortunate result of damage done to the hair through chemicals, harsh treatment, and/or environmental factors, such as overexposure to the sun. This damage manifests itself as gaps or holes in the protective layer that the individual cuticle scales form. Hair in this state is even more prone to breakage. Highly porous hair is capable of absorbing water up to 55% by weight. Total immersion in water can create stress on the hair; because of the extra weight, the hair is too weak to support the excess of moisture, causing a loss in elasticity. This hair type takes to chemicals very easily and in higher concentrations due to the openings in the shaft. There is little recourse for alleviating high porosity except regular trims to cut away the damage and taking better care of the hair as directed below as it grows.
Stay away from humectants (products that draw moisture in from the atmosphere)–particularly in high heat and humid climates–as they will draw in an excessive amount moisture, weighing down the hair and causing frizz and tangles as well as a loss in elasticity. Instead, use light, highly moisturizing products. Protein-containing products should be a regular part of this hair type’s routine in order to patch up the gaps in the cuticle layer. Products with a low pH are best as they aid in flattening the cuticle scales, sealing the cuticle. Avoid harsh surfactants and soaps. Treat your hair gently and only detangle when the hair is wet and saturated with conditioner. Most importantly, STAY AWAY FROM HEAT AND CHEMICALS.
What Are the Determining Factors in Porosity?
Largely, genetics. The shape of your hair, whether the strand is round, elliptical, flat; straight, wavy, curly, kinky-curly, or kinky can have an effect on porosity because the the curlier the hair is, the more cuticle scales there are that are unable to lie flat and overlap.
Environmental exposure can have an effect on the hair. Prolonged UV rays can fuse cuticle scales together and cause further damage to the cuticle layer.
Heat styling can cause irreparable damage to the cuticle layer AND cortex. Heat can cause the water in the hair to heat past the boiling point and rupture hair from the inside.
Mechanical damage from combing, brushing, hair rubbing against clothing, and styling can also cause damage to the cuticle and over time will tear it.
Sulfates and soaps will dissolve the lipid layer (the hair is comprised of not only protein, but a protective fatty acid layer that blocks out water and a cell membrane complex under the scales, which holds the scales firmly in place) and cause the hair to take on too much water, causing frizz, tangling, and further cuticle damage. Soaps can permanently destroy the cuticle layer creating highly porous hair. Use sulfate-free shampoos or alternative hair washes like bentonite clay or diluted apple cider vinegar rinses instead (ACV must contain the ingredient “mother”)
Chemical processes, such as relaxers and color, require that the cuticle layer be raised using an alkaline solution in order to penetrate the interior of the hair shaft and make permanent changes to the protein structure of the hair. Those processes are capable of causing permanent damage to the cuticle layer. Repeated use of these processes can cause a greater amount of damage with every use. Bleach is the harshest and most damaging, followed by perms and tex-laxers, with permanent coloring being the mildest.
While all these reasons hold true, porosity issues can also be caused by natural irregularities in natural hair.
How Do I Test the Porosity of My Hair?
***Always test for porosity on clean, product-free hair for more accurate results***
1.) The Float Test: Take a couple of strands from your comb after washing, allow the hair to dry, and set them in a bowl or glass of room temperature water. Leave it for 2 – 4 minutes and then check them. If your hair floats at the top, you have low porosity. If your hair floats in the middle, you have normal porosity. If your hair sinks to the bottom, you have high porosity.
2.) The Strand Test: Grab a strand if hair with your thumb and index finger. With your other hand, use your thumb and index finger and slide them up the hair strand from end to root. If you feel any irregularities that feel like the usual twists and turns of natural hair, it’s normal. If you catch any snags, the hair is highly porous. If you smooth your finger up the strand and feel nothing, it’s low porosity.
3.) The Wet/Dry Test: During your next wash day, pay attention to how long it takes for your hair to become saturated. If it takes a while, you may have low porosity. If it immediately becomes saturated, you may have high porosity. After washing, take note of how long it takes your hair to dry. If it dries in a short period of time, your hair may be highly porous. If it takes a long time, then the hair is low in porosity.
Before doing my research for this article, I had always thought my hair was highly porous. Come to find out, my hair actually has low porosity! After finishing my draft, I utilized the three different tests to find out my hair’s porosity and then payed careful attention to my hair as I washed, moisturized, and sealed. My hair did, indeed, feel like products just sit on it, particularly at the ends.
I realized that I tend to try and re-wet my hair right after applying product because THEN it feels like the moisture really is penetrating my hair. My hair is always at its best after a deep treatment. The one thing I don’t agree with when it comes to the findings of my research was the statement that low porosity hair should keep away from heavy butters and oils, and in some cases, oil altogether. I beg to differ. My hair loves butters and heavy oils! The reason I believe that to be true is because those butters and heavier oils keep my hair moisturized for longer periods of time and low porosity hair needs to retain all the moisture it can because of the difficulty in penetrating the cuticle layer.
Mango butter and castor oil work wonderfully in my hair. I’ve stopped using castor oil on the whole of my hair since starting the Curly Girl Method (it’s not on the approved products list because it is a wax, but they say jojoba is fine. Jojoba oil is a wax ester. Must look into that), but when I was using it on the whole of my hair it would stay moisturized from one wash day to the next. I still use it on my edges since they are constantly exposed and the moisture is often washed out by soap from bathing and also from washing my face at night; I do also use it on my ends to preserve them as best I can.
Do you know your hair’s porosity? If so, how has it affected your hair care routine? If not, then perform the three porosity tests and see if you need to adjust your regimen and products.