6.9 Skin Typing, Conditions & Wood's Lamp Analysis
Key Takeaways
- The Fitzpatrick scale classifies skin types I through VI by response to ultraviolet exposure, predicting burning and tanning tendency and post-inflammatory hyperpigmentation risk.
- The Glogau scale grades photoaging from I (no wrinkles) through IV (only wrinkles), independent of Fitzpatrick type.
- Skin type is genetically determined and fixed, while skin condition such as dehydration, sensitivity or congestion is changeable and is the actual treatment target.
- Fitzpatrick types IV through VI carry elevated post-inflammatory hyperpigmentation risk and warrant lower acid concentrations and pre-treatment with tyrosinase inhibitors.
- A Wood's lamp uses filtered ultraviolet light near 365 nanometers; Cutibacterium acnes coproporphyrins fluoresce bright orange-pink, and thin or dehydrated skin appears light violet.
Last updated: August 2026
6.9 Skin Typing, Conditions & Wood's Lamp Analysis
1. Skin Typing Systems: Fitzpatrick & Glogau Scales
Skin typing systems categorize skin based on genetic melanin production, baseline reaction to ultraviolet light, and lifetime photoaging severity.
The Fitzpatrick Classification Scale
Developed in 1975 by Harvard dermatologist Thomas B. Fitzpatrick, this scale evaluates genetic skin phototypes (Types I through VI) based on baseline sunburn tendency and tanning response following initial 45–60 minute summer midday sun exposure.
┌──────────────────────────────────────────────────────────┐
│ THE FITZPATRICK SKIN CLASSIFICATION SCALE │
└────────────────────────────┬─────────────────────────────┘
│
┌───────────────┬───────────────────────────────────┬───────────────────────────────────┬───────────────────────────────┐
│ PHOTOTYPE │ UNPROTECTED UV REACTION │ PHYSICAL CHARACTERISTICS │ CLINICAL ESTHETIC RISKS │
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE I │ Always burns, never tans │ Very fair, pale ivory, red hair, │ Extreme skin cancer risk; │
│ │ Extremely sun-sensitive │ freckles, blue/green eyes │ high erythema sensitivity │
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE II │ Burns easily, tans minimally │ Fair skin, light blonde/brown │ High sunburn risk; prone to │
│ │ High sun sensitivity │ hair, blue, hazel, or green eyes │ premature photoaging │
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE III │ Sometimes burns, gradually tans │ Fair to light olive skin, brown │ Moderate sun risk; burns early│
│ │ to light olive brown; moderate │ hair, brown or hazel eyes │ in season, tans gradually │
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE IV │ Burns minimally, always tans │ Olive/light brown skin, dark │ High risk of PIH; requires │
│ │ easily; Mediterranean/Asian/Latin │ brown hair, dark brown eyes │ tyrosinase inhibitors pre-peel│
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE V │ Rarely burns, tans darkly and │ Deeply pigmented brown skin, │ Extreme risk of PIH; prone │
│ │ profusely; Middle Eastern/Indian │ dark hair, dark eyes │ to hypertrophic keloid scars │
├───────────────┼───────────────────────────────────┼───────────────────────────────────┼───────────────────────────────┤
│ TYPE VI │ Never burns, deeply pigmented │ Deepest black/dark brown skin, │ Highest risk of PIH, keloids, │
│ │ African/Indigenous heritage │ black hair, dark brown eyes │ and hypopigmentation trauma │
└───────────────┴───────────────────────────────────┴───────────────────────────────────┴───────────────────────────────┘
- Significance for Estheticians: Higher Fitzpatrick phototypes (Types IV, V, and VI) possess highly active, reactive melanocytes. Aggressive chemical peels, high-heat lasers, or over-exfoliation can provoke severe, disfiguring Post-Inflammatory Hyperpigmentation (PIH) or post-traumatic hypopigmentation. Estheticians must prep Fitzpatrick IV–VI skin with tyrosinase inhibitors for 2 to 4 weeks before superficial peels and utilize lower acid concentrations.
The Glogau Photoaging Classification Scale
The Glogau scale measures the objective degree of cutaneous photoaging, actinic damage, and wrinkle development.
- Type I (Mild Photoaging - Age 20s to 30s): Early photoaging; no keratoses; minimal or no wrinkles; mild pigment changes; requires minimal or no makeup.
- Type II (Moderate Photoaging - Age 30s to 40s): Early to moderate photoaging; wrinkles in motion (dynamic lines around eyes/mouth during facial animation); early solar lentigines; palpable mild keratoses; usually wears some foundation.
- Type III (Advanced Photoaging - Age 50s and older): Advanced photoaging; wrinkles at rest (static lines visible even when face is relaxed); prominent solar lentigines, dyschromia, visible telangiectasias, and visible actinic keratoses; always wears heavy foundation.
- Type IV (Severe Photoaging - Age 60s to 70s+): Severe photoaging; generalized wrinkling across the entire facial surface; yellow-gray cutaneous tone; actinic keratoses with or without prior skin cancers; makeup cakes and fissures.
2. Skin Types vs. Skin Conditions
One of the most foundational distinctions in esthetics is differentiating between a client's genetic skin type and their acquired skin conditions.
┌──────────────────────────────────────────────────────────┐
│ SKIN TYPES VS. SKIN CONDITIONS │
└────────────────────────────┬─────────────────────────────┘
│
┌──────────────────────────────┴──────────────────────────────┐
▼ ▼
┌──────────────────────────────┐ ┌──────────────────────────────┐
│ GENETIC SKIN TYPE │ │ ACQUIRED SKIN CONDITION │
│ (Genetically Fixed) │ │ (Temporary & Treatable) │
├──────────────────────────────┤ ├──────────────────────────────┤
│ • Determined by genetics │ │ • Triggered by environment, │
│ • Governed by lipid output │ │ lifestyle, hormones, age │
│ • Based on pore follicle size│ │ • Can fluctuate dynamically │
│ • CANNOT be permanently │ │ • Highly responsive to │
│ changed by skincare │ │ professional treatment │
└──────────────────────────────┘ └──────────────────────────────┘
Genetic Skin Types (Lipid / Sebum Profile)
- Dry (Alipidic) Skin: Characterized by underactive sebaceous glands that produce insufficient sebum/lipids. Pores are very small or barely visible over the entire face. Lacks natural lipid lubrication, exhibiting a dull, taut, rough texture, prone to superficial flaking and premature fine lines.
- Oily (Lipidic) Skin: Characterized by overactive sebaceous glands producing excess sebum. Follicles/pores are medium to large and visible throughout the entire face (forehead, nose, cheeks, chin). Exhibits a shiny, thick texture, prone to open/closed comedones and acne breakouts.
- Combination Skin: The most common skin type. Features medium-to-large pores and higher sebum production in the central T-zone (forehead, nose, chin), with normal-to-small pores and lower sebum production on the cheeks and lateral jawline.
- Normal Skin: Exhibits optimal, balanced sebum and hydration levels. Pores are small to medium in the T-zone and barely visible on cheeks; smooth, resilient texture with even tone and no severe blemishes.
Acquired Skin Conditions (Treatable Variables)
- Dehydrated Skin: Characterized by a lack of water/moisture in the stratum corneum (distinct from alipidic dry skin, which lacks oil). Dehydrated skin can occur in any skin type—even oily skin. When pinched gently, dehydrated skin exhibits fine crepey superficial lines.
- Sensitive vs. Sensitized Skin:
- Sensitive Skin: A genetic predisposition featuring a naturally thin epidermal barrier, low lipid levels, and superficial microvasculature prone to flushing and erythema.
- Sensitized Skin: An acquired, transient barrier impairment caused by external environmental factors, over-exfoliation, harsh detergents, or allergic contact dermatitis.
- Mature / Aging Skin: Loss of dermal collagen, elastin, and subcutaneous adipose tissue; decreased cellular turnover rate, dryness, laxity, and static rhytids (wrinkles).
- Asphyxiated Skin: Characterized by dull, sallow, grayish discoloration, clogged pores, and sluggish microcirculation, commonly observed in chronic tobacco smokers or individuals residing in heavily polluted environments.
3. Diagnostic Skin Analysis: The Wood's Lamp
The Wood's Lamp (invented by American physicist Robert Wood) is a diagnostic skin analysis instrument utilizing a filtered black-light arc with a nickel oxide filter emitting long-wave ultraviolet radiation at a wavelength of 365 nanometers (nm). It causes subsurface skin conditions, fungal infections, and bacterial porphyrins to fluoresce in distinct, recognizable colors in a completely darkened room.
┌──────────────────────────────────────────────────────────┐
│ WOOD'S LAMP (365 nm) FLUORESCENCE GUIDE │
└────────────────────────────┬─────────────────────────────┘
│
┌───────────────────────────────────┬───────────────────────────────────────────────────────────────────────────┐
│ FLUORESCENT COLOR │ DIAGNOSTIC CLINICAL INTERPRETATION │
├───────────────────────────────────┼───────────────────────────────────────────────────────────────────────────┤
│ Blue-White │ Normal, healthy, well-hydrated, balanced skin │
│ Bright Fluorescent White │ Thickened stratum corneum / Hyperkeratosis / Compacted dead skin cells │
│ Yellow / Orange / Pink │ Follicular sebum, open comedones, and active Cutibacterium acnes bacteria │
│ Light Purple / Violet │ Dehydrated skin lacking epidermal moisture content │
│ Brown / Dark Brown │ Hyperpigmentation, solar lentigines, melasma, and dermal sun damage │
│ Green / Yellow-Green │ Fungal infection (such as Tinea versicolor / Malassezia furfur) │
└───────────────────────────────────┴───────────────────────────────────────────────────────────────────────────┘
- Biochemical Basis of Pink/Orange Glow: The yellow, orange, or copper-pink pinpoint fluorescence observed in active acne follicles is produced by coproporphyrins—naturally fluorescing metabolic waste products synthesized by Cutibacterium acnes bacteria.
Exam Memory Anchors — Consultation & Diagnostics:
- Accutane Waiting Period: 6 months to 1 full year before waxing or chemical peeling.
- Retin-A Cessation: 48 to 72 hours prior to facial waxing/peels.
- Wood's Lamp Colors:
- Blue-White = Normal/Healthy
- Bright White = Thick Cornified Layer (Hyperkeratosis)
- Yellow/Orange/Pink = Sebum, Comedones & C. acnes bacteria
- Purple/Violet = Dehydration
- Brown = Hyperpigmentation/Sun Damage
- Green = Fungal Infection
- Dry vs Dehydrated: Dry = Lacks Oil (Lipids); Dehydrated = Lacks Water (Moisture).
Test Your Knowledge
During a skin analysis using a Wood's Lamp (365 nm filtered black light), the esthetician observes bright fluorescent orange-pink pinpoint fluorescence along the client's T-zone and light violet fluorescence across the cheeks. How should these diagnostic findings be interpreted?
A
B
C
D
Test Your Knowledge
Which of the following client medical conditions presents an absolute contraindication to the use of electrotherapy modalities such as Galvanic current, High-Frequency (Tesla), and Microcurrent during a facial service?
A
B
C
D