Comprehensive Guide to Hair Analysis, Growth Patterns, Scalp Conditions, and Hair Growth Cycles

Hair and Scalp Analysis

Core Components of Hair Analysis:
- Evaluating hair texture.
- Evaluating hair density.
- Evaluating hair porosity.
- Evaluating hair elasticity.
- Evaluating wave patterns.
- Evaluating growth patterns.
- Evaluating the oiliness or dryness of the hair and scalp.
Hair Porosity:
- Definition and Characteristics: Porosity refers to the hair's ability to absorb moisture. Different degrees of porosity can be found across all hair textures, and an individual can exhibit different degrees of porosity in different areas of the head.
- Testing Procedure for Porosity:
  1. Conduct the test on dry hair.
  2. Take a strand of several hairs from four distinct areas of the head: front hairline, temple, crown, and nape.
  3. Hold the strand securely near the end with one hand.
  4. Slide the thumb and forefinger of the other hand from the end of the hair strand down to the scalp.
- Diagnostic Porosity Results:
  - Low Porosity: Hair feels smooth, and the cuticle is compact, dense, and hard.
  - Porous Hair: A slight roughness is felt as the fingers slide toward the scalp.
  - High Porosity: Hair feels very rough, dry, or breaks during testing. This indicates the hair is highly porous and may have been overprocessed by chemical or thermal services.
Hair Elasticity:
- Definition: Hair elasticity is the ability of the hair to stretch and return to its original length without breaking.
- Structural Basis: Elasticity is an indicator and reflection of the strength of the side bonds located within the cortex.
- Elasticity Benchmarks:
  - Wet Hair with Average Elasticity: Will stretch between $30\text{ percent}$ to $50\text{ percent}$ ( $30$ to $50$ percent) of its original length and return to that exact length without breaking.
  - Dry Hair with Average Elasticity: Stretches about $20\text{ percent}$ ( $20$ percent) of its length.
- Characteristics and Pathology of Low Elasticity Hair:
  - Feels brittle and breaks easily.
  - Incapable of holding a curl from wet setting, thermal styling, or permanent waving.
  - Result of weak side bonds caused by overprocessing or physical damage from thermal styling tools.
  - Requires chemical solutions with a lower $pH$ to minimize further structural damage.
  - May fail to maintain a strong curl pattern when chemical services are performed.
- Testing Procedure for Elasticity:
  1. Conduct the test on wet hair across four separate areas of the head (front hairline, temple, crown, and nape) because elasticity can vary across the head.
  2. Place a strand of wet hair between the thumb and index finger at mid-strand.
  3. Place the thumb and index finger of the other hand near the end of the strand.
  4. Hold the strand securely and attempt to stretch the hair.
  5. Evaluation: If the hair stretches and returns to its original length without breaking, it has average elasticity. If the hair breaks easily or fails to return to its original length, it has low elasticity.
Quick Reference Hair Analysis Questions:
- Texture: Does hair look more like thread (fine) or yarn (coarse)?
- Density: Can you easily see the scalp through the hair (low/thin density) or not (high/thick density)?
- Porosity: Does hair feel smooth (low porosity) or rough (high porosity) when sliding thumb and forefinger from end to scalp?
- Elasticity: Does hair stretch and return (average elasticity) or break (low elasticity) when pulling a strand between fingers?

Hair Growth Patterns

Follicular Angulation and Origins: Hair growth patterns are critical factors when cutting or styling hair. They result from hair follicles growing out of the scalp at a perpendicular $90^\text{o}$ angle (or in a straight direction from the head).
The Three Primary Hair Growth Patterns:
- Hair Stream:
  - Characterized by hair flowing in the exact same direction.
  - Caused by follicles sloping in the same direction.
  - A natural part is formed when two hair streams flow in opposite directions.
- Whorl:
  - Occurs when hair leaves the follicles at an angle.
  - Hair forms a distinct circular growth pattern.
  - An individual head can occasionally feature more than one whorl.
- Cowlick:
  - Occurs when hair grows straight up or at a distinctly different angle than the surrounding hair.
  - Cowlicks are usually more noticeable at the crown of the head, but they may be located anywhere on the head.

Scalp and Hair Conditions: Dry vs. Oily

Dry Hair and Scalp:
- Etiology: Caused by inactive sebaceous glands that produce an insufficient amount of sebum.
- Aggravating Factors: Excessive shampooing and changes in environmental climate.
- Symptomatology: Lack of sebum causes hair to appear dull, dry, and lifeless.
- Treatment Recommendations: Treat dry hair and scalp using specialized products formulated with moisturizers and emollients.
- Contraindications & Avoidance: Individuals with dry hair and scalp must avoid frequent shampooing, strong soaps, harsh detergents, and products with high alcohol content.
- Diagnostic Caution: Do not confuse naturally dry hair with overly porous hair that has been damaged by thermal styling tools, chemical services, or harsh environmental conditions.
Oily Hair and Scalp:
- Etiology: Caused by overactive sebaceous glands producing excess sebum.
- Treatment Recommendations: Use shampoos specifically formulated to help return the scalp to its natural $pH$ level.
- Contraindications & Avoidance: Avoid products that are overly harsh or stripping, as harsh chemical exposure can trigger additional compensatory oil production.
- Rinsing Protocol: Always thoroughly rinse hair following shampooing to remove all detergent residue.

Types of Body Hair

Classification: Body hair is divided into three distinct types: Lanugo hair, Vellus hair, and Terminal hair.
Lanugo Hair:
- Short, fine, unpigmented hair covering a fetus.
- Generally sheds completely within a few weeks following birth.
Vellus Hair:
- Short, fine, unpigmented body hair, frequently referred to as "peach fuzz".
- Typically less than $1/3\text{ inch}$ long (approximately $1\text{ cm}$ long; represented at $1\text{ mm}$ length under $\times 50$ magnification).
- Can appear anywhere on the human skin except for the palms of the hands, soles of the feet, and the lips.
- The follicles that produce vellus hair do not possess sebaceous glands.
- Primary Function: Helps facilitate the evaporation of perspiration and aids in body temperature regulation.
Terminal Hair:
- Long, pigmented hair present on the scalp and body.
- Can grow up to $3\text{ feet}$ long.
- Coarser than vellus hair and, with the exception of gray hair, is fully pigmented.
- May contain an internal medulla layer.
Follicular Transition Capacity:
- All hair follicles are capable of producing either vellus hair or terminal hair.
- Transitions between producing vellus or terminal hair depend upon genetics, age, and hormone levels.

The Hair Growth Cycle

Overview: Hair grows in a continuous cyclical process that typically lasts between $2\text{ years}$ to $6\text{ years}$ . The cycle consists of three sequential phases: Anagen, Catagen, and Telogen.
Anagen Phase (Growth Phase):
- Active growth stage during which new hair is produced.
- New cells are produced inside the follicle faster than any other cell type in the human body.
- Growth Rate: The average growth rate for healthy scalp hair is approximately $0.5\text{ inch}$ ( $1.25\text{ cm}$ ) per month.
- Demographic Variations: Growth rate varies according to age and gender. Scalp hair grows rapidly between the ages of $15$ and $30$ , but slows down sharply after age 50$.\n * **Proportion:** Approximately 90 ext{ percent} $($ 90 percent) of scalp hair is in the anagen phase at any given time.\n * **Duration:** Lasts from 2 ext{ years} $to$ 6 ext{ years} $, but can extend up to$ 10 ext{ years}. This duration differential explains why some individuals' hair cannot grow beyond a certain length, whereas others can grow exceptionally long hair.\n\n* **Catagen Phase (Transition Phase):**\n * Brief transitional period between the follicle's active growth phase and resting phase.\n * **Structural Manifestations:**\n * The follicle canal shrinks and detaches from the dermal papilla.\n * The hair bulb disappears, and the shrunken root end forms a rounded club.\n * **Proportion:** Less than 1 ext{ percent} $($ 1 percent) of scalp hair is in the catagen phase at any given time.\n * **Duration:** Lasts 1 ext{ week} $to$ 2 ext{ weeks}.\n\n* **Telogen Phase (Resting Phase):**\n * The final, resting phase of the hair growth cycle.\n * **Shedding Dynamics:** The hair either sheds or remains anchored in place until the subsequent anagen phase, where the emerging new hair pushes it out.\n * **Daily Loss Rate:** Hair shedding is a natural physiological process. It is common to shed between 50 $to$ 100 hairs per day.\n * **Proportion:** A little less than 10 ext{ percent} $($ 10 percent) of scalp hair is in the telogen phase at any given time.\n * **Duration:** Lasts 3 ext{ months} $to$ 6 ext{ months}.\n * *Pathological Note:* Common types of hair loss and their underlying pathology are addressed separately in Chapter 08, Hair and Scalp Disorders.\n\n# Questions & Discussion\n\n* **Classroom Hair Analysis Activity:**\n * *Task:* Form groups of two or more to evaluate each other's hair across seven core parameters: texture, density, porosity, elasticity, wave patterns, growth patterns, and oiliness/dryness of the hair and scalp. Document all findings and present an oral report to the class identifying the most common texture and density observed.\n\n* **Product Research Task:**\n * *Task:* Conduct research into professional products to generate a customized list of recommended shampoos and conditioners for clients presenting with dry hair and scalp, as well as clients presenting with oily hair and scalp.\n\n* **Check-In Question 10:** What are the components of a hair analysis?\n * *Response:* A comprehensive hair analysis comprises evaluating seven distinct properties: hair texture, hair density, hair porosity, hair elasticity, wave patterns, growth patterns, and the oiliness or dryness of both the hair and scalp.\n\n* **Check-In Question 11:** What causes dry scalp and oily scalp? What treatments would be beneficial for each?\n * *Response:* \n * *Dry Scalp Causes & Treatments:* Caused by inactive sebaceous glands that produce insufficient sebum. Aggravated by frequent shampooing and climate shifts. Beneficial treatments include using hair products containing moisturizers and emollients, while avoiding frequent washing, strong soaps, harsh detergents, and high-alcohol formulas.\n * *Oily Scalp Causes & Treatments:* Caused by overactive sebaceous glands that produce excessive sebum. Beneficial treatments include using shampoos formulated to restore the scalp to its natural pH$$, avoiding overly harsh products that trigger compensatory oil production, and thoroughly rinsing hair following every shampoo service.