The scalp and hair profile is defined by your scalp's genetic characteristics; follicle size and shape, scalp sensitivity level and hydration, and sebum secretion.
01. FOLLICLE SIZE & SHAPE
The size and shape of the follicle determines the hair's diameter and its curl pattern (what's referred to as hair type).
What is it? The size of the follicle determines the diameter or width of each individual hair strand. There is fine, medium and coarse diameter.
Why it's important? It is related to your hair's strength, the finer the diameter the more fragile it is because it has no medulla. It also tells us how well your hair holds hairstyles. Fine hair is easily damaged by bleaches and chemicals and prone to traction alopecia from dreadlocks and braids.
What is it? The shape of the hair follicle determines the hair's curl pattern (straight, wavy or curly). If your follicles are round, hair will tend to grow straight, while oval follicles will give wavy hair and eliptical-shaped follicles will give you curly and coily hair. The hair typing system/curl chart created by Andre Walker (type 1,2,3,4) is based on follicle shape.
Why it's important? The tighter the curl pattern the more fragile the hair is and prone to breakage, it requires extra care when styling and handling. The tighter the curl pattern the harder it is for sebum to coat the entire hair shaft, this will result in drier hair, particularly the hair ends.
02. SCALP HYDRATION & SENSITIVITY LEVELS
We all have a protective outer layer on our scalp. This barrier is a layer of lipids, composed of ceramides, cholesterol and fatty acids produced by keratinocytes in the stratum corneum layer of epidermis. It performs two main jobs: keeping water in, and keeping potentially damaging things, like UV rays, wind, heat, and harsh chemicals, out. If you have a sensitive scalp, this barrier is typically weaker, thinner, and more easily damaged, making it easier for irritants to penetrate the scalp and cause inflammation.
03. SEBUM SECRETION
What is it? Sebum is the natural oil produced by sebaceous glands in the scalp.
Why it's important? Healthy hair grows out of a healthy scalp. Under or overproduction of sebum is an indication of an unbalanced scalp, which may require a consultation with a trichologist.