3.1 Hair & Scalp Analysis
Key Takeaways
- Hair has three layers: the protective cuticle, the strength-and-color cortex, and the often-absent medulla.
- The hair growth cycle runs anagen (growth, ~90% of scalp hair), catagen (transition), then telogen (rest/shed).
- Porosity, density, texture, and elasticity are the four characteristics that drive every service decision.
- On the Texas exam, hair and scalp content is the single largest area at roughly 40% of the 100 questions.
- Cosmetologists analyze and treat hair and scalp but never diagnose disease — refer suspected disorders to a physician.
3.1 Hair & Scalp Analysis
Hair and scalp analysis is the most heavily weighted topic on the Texas Department of Licensing and Regulation (TDLR) written exam: hair and scalp content makes up roughly 40% of the 100 multiple-choice questions, so master this section first. Analysis is the science-based examination of the hair and scalp that determines which products and services are safe and appropriate. A cosmetologist may analyze and treat hair and scalp, but may never diagnose or prescribe for a disease — that crosses into the practice of medicine and must be referred to a physician.
Hair Structure
Trichology is the scientific study of hair. Each strand has two main parts: the hair root (below the skin, inside the follicle) and the hair shaft (the visible portion above the skin). Key root structures:
- Follicle — the tube-like depression that holds the root.
- Bulb — the thickened, lowermost part that fits over the papilla.
- Dermal papilla — a cone of connective tissue with the blood supply and nerves that feed hair growth.
- Arrector pili — the small involuntary muscle that causes "goosebumps" and makes hair stand up.
- Sebaceous (oil) glands — secrete sebum, the natural oil that lubricates the hair and scalp.
The shaft has three layers, tested often:
| Layer | Location | Function |
|---|---|---|
| Cuticle | Outermost | Overlapping, scale-like cells that protect the strand; raised by alkaline products |
| Cortex | Middle | ~90% of hair weight; holds melanin (color) and the bonds that give strength, texture, and elasticity |
| Medulla | Innermost | Soft, often absent in fine and naturally blond hair |
Chemically, hair is keratin, a fibrous protein made of long amino-acid chains held by side bonds: weak hydrogen and salt bonds (broken by water or heat, reformed on drying) and strong disulfide bonds (broken only by chemical relaxers or permanent waves).
Hair Growth Cycle
The exam tests the three phases in order:
- Anagen — the active growth phase; about 90% of scalp hair is in anagen at any time, lasting 3–5 years.
- Catagen — the brief transition phase (1–2 weeks) when growth stops.
- Telogen — the resting/shedding phase; hair falls and the follicle re-enters anagen. Average healthy scalp loss is 35–80 hairs per day.
The Four Hair Characteristics
Worked example: a client wants a one-process color. You test a strand and it stretches more than 50% then breaks without returning — that is low elasticity, signaling damage, so you choose a gentler formula or reschedule a conditioning treatment first.
- Texture — diameter of the strand: coarse, medium, or fine. Coarse hair is hardest to penetrate and process.
- Density — number of hairs per square inch (low, medium, high). Density is not the same as texture.
- Porosity — the hair's ability to absorb moisture/chemicals. High (overly) porous hair has a raised cuticle and processes fast; low porosity resists penetration and needs more processing time or heat.
- Elasticity — the ability to stretch and return. Dry hair should stretch ~20% and wet hair up to ~50% without breaking.
Scalp Conditions and Consultation
During the consultation, examine the scalp for tightness, oiliness, dryness, and disorders. Know these tested terms: dandruff (pityriasis), alopecia (hair loss; androgenic alopecia is genetic, alopecia areata is sudden patchy loss), and canities (gray hair). Infectious or inflamed conditions such as tinea (ringworm), scabies, pediculosis capitis (head lice), or open lesions are contraindications — do not service the client; refer them to a physician. A trap question: a fungal ring on the scalp is never treatable in the salon.
Why Analysis Drives Every Service
The consultation ties analysis to recommendation. A worked sequence: greet the client, drape, then examine the hair dry and wet. Note that fine, low-density, low-porosity hair processes slowly and resists chemicals, so you extend timing or add gentle heat. Coarse, high-density, high-porosity hair processes fast and can over-process, so you shorten timing and watch closely. You then match the finding to the service: damaged, low-elasticity hair gets a strengthening protein treatment before any color or perm; an oily scalp gets a balancing shampoo; a dry, flaky (non-infectious) scalp gets a moisturizing scalp treatment.
Record findings on the client record card so future visits build on the analysis. Keep the scope-of-practice line clear, because the exam tests it repeatedly: a cosmetologist examines, recommends products, and performs cosmetic services, but the moment a condition looks infectious, inflamed, or like a disease, the only correct action is to stop and refer to a physician. You never name a disease to the client, never treat ringworm or lice, and never service a client with open lesions or contagious conditions. This protects the client, the next client, and your license under Texas rules.
Finally, remember the difference between density and texture, a classic distractor: density counts how many strands grow per square inch, while texture measures the thickness of an individual strand. A client can have fine texture with high density (many thin hairs) or coarse texture with low density (few thick hairs), and each combination changes how you cut, color, and style.
A client's hair stretches well past its normal length when wet and then breaks without springing back. Which hair characteristic is deficient?
Which layer of the hair shaft contains the melanin and the bonds responsible for hair strength and the results of permanent waving?