Hair Porosity: A Guide to Managing Moisture

Hair porosity refers to the ability of the hair strand to absorb and hold moisture. It is determined by the condition of the cuticle, the outermost layer of the hair shaft. When the cuticle scales are tightly bound, the hair is considered low porosity; when they are lifted or widely spaced, it is high porosity.

Correcting for dryness begins by identifying where your hair falls on this spectrum. Once you understand your porosity, you can select products that align with your hair's specific absorption needs rather than guessing with heavy emollients that may be doing more harm than good.

1. The water glass test. Place a single clean, product-free strand of hair into a glass of room-temperature water. Let it sit for four minutes. If the hair floats at the top, it is low porosity. If it sinks to the middle, it is medium. If it drops to the bottom, it is high porosity.
2. Clarify the surface. Low porosity hair often suffers from product buildup, while high porosity hair needs a clean slate to accept moisture. Use a mild clarifying shampoo once a week to remove residue. Massage the scalp gently without tangling the lengths to ensure the cuticle is ready for conditioning.
3. Condition with heat. Low porosity hair benefits from heat to open the cuticle, so use a steamer or a warm towel over your hair while the conditioner sits. For high porosity hair, use cool water for your final rinse to help seal the cuticle scales down after applying a protein-based conditioner.
4. Seal the moisture. Immediately apply a lightweight oil or leave-in conditioner while the hair is damp. High porosity hair requires thicker, butter-based sealants to prevent moisture evaporation. Low porosity hair should stick to water-based, lightweight humectants that do not weigh down the strand.

Moisture is only useful if your hair has the structural capacity to hold it.