DE Cosmetology cheat sheet

Hair structure: cuticle (outer protective layer), cortex (middle, contains melanin and determines strength/elasticity), medulla (innermost, may be absent in fine hair).

pH scale: hair and skin ~4.5–5.5; hair swells and cuticle opens in alkaline solutions (pH > 7); acidic solutions (pH < 7) contract cuticle and add shine.

Color theory: primary colors are red, yellow, blue; secondary are orange (red+yellow), green (yellow+blue), violet (red+blue); complementary colors neutralize (e.g., blue cancels orange).

Developer (hydrogen peroxide) volumes: 10 vol = 3% lifts 1 level; 20 vol = 6% lifts 2; 30 vol = 9% lifts 3; 40 vol = 12% lifts 4. Mixing ratio for permanent color is typically 1:1 or 1:2 depending on manufacturer.

Relaxer chemistry: ammonium thioglycolate (pH ~9.0–9.5) breaks disulfide bonds; sodium hydroxide (lye, pH ~13) and guanidine hydroxide (no-lye) also break bonds. Neutralizer (hydrogen peroxide or sodium bromate) re-forms bonds.

Thermal styling safety: curling iron temperature 250–450°F depending on hair type; press comb 300–450°F; always test on a paper towel or small section; use heat protectant.

Sanitation vs. disinfection: sanitation reduces pathogens; disinfection destroys most pathogens on nonporous surfaces using EPA-registered hospital-grade disinfectant; sterilization destroys all microbial life (autoclave).

Wet hair is weaker and stretches 40–50% of its length; dry hair stretches 20%; elasticity test assesses protein balance; porosity test (float test) assesses cuticle condition.

Sectioning for haircutting: unity of form, balance, and proportion; angles: 0° = one length, 45° = graduated, 90° = uniform layers, 180° = long layers; elevation determines volume.

Clipper guard sizes: #1 = 1/8 inch (3 mm), #2 = 1/4 inch (6 mm), #3 = 3/8 inch (10 mm), #4 = 1/2 inch (13 mm); blade numbers increase with length.

Razor cutting: straight razor held at a 30° angle or less to the skin; always use a fresh blade; stretch skin taut; cut in the direction of hair growth to avoid irritation.

Beard and mustache shapes: goatee (chin only), Van Dyke (goatee plus detached mustache), Balbo (chin and jawline connected), full beard; outline with trimmers then refine with razor.

Facial hair growth cycles: anagen (growth), catagen (transition), telogen (rest); shaving does not change hair thickness or growth rate.

Hot towel preparation: 100–115°F (38–46°C) for 2–3 minutes softens beard and opens pores; do not use on clients with sensitive skin or rosacea without caution.

Shaving lather: apply with a badger or synthetic brush in circular motions to lift hair; lather should be thick and wet; re-lather before each pass.

Men's haircut terminology: taper (gradual fade), fade (blend to skin), crew cut (short on top, tapered sides), pompadour (volume at front), flat top (level top).

Sanitation for barbering: barbicide (quaternary ammonium) for combs and shears; clipper blades disinfected after each client; razors are single-use and disposed in sharps container.

Hair and scalp analysis: check for lice, ringworm, folliculitis, and contraindications before service; do not proceed with broken skin or infectious conditions.

Skin types: normal, dry, oily, combination, sensitive; Fitzpatrick scale I–VI classifies sun reactivity and guides treatment intensity.

Facial massage movements: effleurage (gliding), petrissage (kneading), tapotement (tapping), friction (circular), vibration; always move from insertion to origin of muscle and follow lymphatic drainage toward nodes.

Exfoliation: mechanical (scrubs, brushes) vs. chemical (AHAs, BHAs); AHA (glycolic, lactic) works on surface; BHA (salicylic) penetrates pores; do not exfoliate over active acne or broken skin.

Waxing temperatures: hard wax 125–135°F (52–57°C), soft wax 95–110°F (35–43°C); test on inner wrist; apply in direction of hair growth, remove against growth; hold skin taut.

Contraindications for facial treatments: active herpes, sunburn, recent chemical peel, isotretinoin use, pregnancy (for certain ingredients), open lesions, infectious skin conditions.

Lymphatic drainage: gentle pressure (light effleurage) toward cervical, submandibular, and clavicular nodes; promotes detoxification and reduces edema.

Makeup color theory: warm undertones (yellow, peach) suit gold, coral, warm reds; cool undertones (pink, blue) suit silver, plum, blue-based reds; neutral can wear both.

Chemical peel depths: superficial (stratum corneum, AHAs 20–30%), medium (papillary dermis, TCA 15–35%), deep (reticular dermis, phenol); only physicians perform medium/deep in most jurisdictions.

Three modalities: galvanic (direct current, produces lye in follicle, destroys germinative cells), thermolysis (high-frequency alternating current, heat destroys tissue), blend (galvanic + thermolysis, most effective for all hair types).

Galvanic electrolysis: current 0.5–1.5 mA, treatment time 10–30 seconds per hair; lye (sodium hydroxide) forms at the cathode (negative pole) at the base of the follicle.

Thermolysis: frequency typically 13.56 MHz; current 0.05–0.3 mA; treatment time 1–5 seconds; uses a single needle and high-frequency energy to coagulate tissue.

Blend method: combines galvanic and thermolysis; current 0.2–1.0 mA, time 5–15 seconds; produces lye and heat for effective destruction of hair matrix.

Needle insertion: insert along the hair shaft to the dermal papilla (depth 2–5 mm depending on area); do not force; observe skin reaction; use sterile, disposable probes.

Hair growth cycles: anagen (active growth, best for treatment), catagen (transition), telogen (resting); treat only anagen hairs for permanent removal; multiple sessions needed.

Contraindications: pacemakers, pregnancy, diabetes (uncontrolled), active infection, keloid tendency, metal implants near treatment area, anticoagulant therapy.

Aftercare: apply antiseptic, avoid sun, makeup, and swimming for 24 hours; keep area clean; report signs of infection; use SPF 30+ on treated areas.

Nail anatomy: nail plate (keratin), nail bed (pink, vascular), cuticle (dead tissue seal), eponychium (living skin at base), hyponychium (seal under free edge), lunula (white half-moon), matrix (growth area).

Nail growth: average 3.5 mm per month (fingernails), toenails 1.6 mm per month; complete replacement of fingernail ~6 months, toenail ~12–18 months.

Nail shapes: square (strongest), squoval, round, oval, almond, stiletto, coffin; file in one direction to avoid splitting; use 180–240 grit for natural nails.

Manicure steps: sanitize hands, shape nails, soak, push cuticles, trim hangnails, massage, base coat, polish, top coat; disinfect implements before and after each client.

Acrylic application: mix liquid monomer (EMA) with powder polymer at ratio 1:1.5; apply thin layers; cure by evaporation; do not use MMA (methyl methacrylate) which is banned in many states.

Gel polish: requires UV/LED lamp (36W for 30–60 seconds); apply base coat, color, top coat; cure each layer; remove by soaking in acetone 10–15 minutes.

Sanitation: implements must be cleaned with soap and water, then disinfected with EPA-registered hospital-grade disinfectant (e.g., quats) for 10 minutes; porous items (emery boards, buffers) are single-use or discarded.

Nail disorders: onychomycosis (fungal infection, contagious), paronychia (bacterial infection of skin around nail), onycholysis (separation of nail plate), pterygium (overgrowth of cuticle); refer to physician.