Hair can be described as having low, normal or high porosity. In each of these types of porosities, the cuticle, or the outer layer of the hair, is a bit different.
In hair with low porosity, the cuticles are compact; they lie flat. Hair with low porosity typically does not absorb moisture very readily. Hair with low porosity tends to resist the absorption of hair color, chemicals, and heat, and is much more difficult to process than hair with normal porosity or high porosity. When the hair is exposed to water, the water may bead up on the hair before it actually begins to absorb.
In hair with normal porosity, the cuticles are raised a bit. The hair will absorb moisture more readily than hair with low porosity.
In hair with high porosity, the cuticles are raised quite a bit. Hair with high porosity absorbs moisture very quickly, which may sound good. However, the tradeoff is that hair with high porosity loses that moisture just as quickly. Damaged hair typically will show strands with high porosity, as harsh combing, coloring, relaxing, excessive heat, and stripping shampoos can damage and tear the cuticle of the hair. Hair with high porosity is also very prone to tangling because the raised cuticles can easily catch on each other. Hair with high porosity, because of its absorptive properties, can easily become over-processed.
The cuticles of the hair are microscopic. How do you know if your cuticles are compact or raised?
- There are a couple of simple tests that you can do to find out your porosity. These tests work best on clean hair, as the results will be more accurate:Take a strand or two of your shed hair and place them in a bowl of water. If the hair stays, your hair likely has low or normal porosity. These porosities are considered to be the porosities of healthy hair. If the hair sinks immediately, or gradually sinks within a minute, the hair likely has high porosity. Again, though fast absorption might seem ideal, the hair will lose that moisture just as quickly, resulting in dry, brittle, and breaking hair.
- Glide your fingers up and down the strand of your hair. If it glides easily in both directions, your hair most likely has low porosity. If it glides fairly easily in one direction, and a teeny bit less easily in the other direction, your hair most likely has normal porosity. If the hair catches or feels rough in one direction or the other, the hair is most likely very porous.
- The hair cuticle naturally lifts when exposed to heat. Therefore, those with low porosity may find that their hair will absorb products more readily when some heat is introduced. Some low porosity folks might like to condition or moisturize their hair under a hooded dryer or a heat cap, or apply their products after a shower with the steam and heat still in the room. Spritzing warm water instead of cool water can also help lift the cuticles a bit.
- Hair with normal porosity is right in the middle of the range; it absorbs just enough moisture, and does not release too much moisture. Care should be taken so that hair with normal porosity does not become hair with high porosity!
- Hair with high porosity may be damaged. To make the hair less porous, protein treatments can be done. Protein replenishes, restores, and strengthens the hair strand. If you look at very porous hair as hair with "holes", protein treatments can help fill those holes so that your hair acts less porous. Those with highly porous hair should take extra care to seal in their moisture with oil or a butter so that they don't lose the moisture, and should carefully protect their hair from further damage.
- Remember that protein is not a moisturizer by any means. It is a way of restoring the hair. Using too much protein can make the hair feel too "structured" - hard, crunchy, and brittle. If you find that protein treatments are making your hair feel like this, you may not need them, or you may want to use them less often. Those with low and normal porosity, especially low porosity, probably will not need to use protein treatments much, as the hair does not have many "holes" that need repairing.