WA Cosmetology cheat sheet

The hair shaft has three main layers: the cuticle (outer scales), cortex (middle, with melanin and strength), and medulla (central core, often absent in fine hair).

The hair follicle cycle has three phases: anagen (active growth, about 2–7 years), catagen (transition, 2–3 weeks), and telogen (rest, 3–4 months).

About 90% of scalp hairs are normally in anagen at any given time; shedding up to roughly 100 hairs per day can be within normal range.

Hair pH is approximately 4.5–5.5; alkaline products raise the cuticle, and acidic products help close and smooth it.

Low-porosity hair has a tight cuticle and resists moisture and chemicals; high-porosity hair absorbs quickly and loses moisture easily.

A blunt cut is executed at 0-degree elevation with a stationary guide, creating a solid perimeter weight line.

A graduated cut uses 45-degree elevation and creates stacked weight; a uniform layer cut uses 90-degree elevation and removes interior weight.

A traveling guide moves with each section and follows the previous cut; a stationary guide remains fixed for the entire section.

Wet hair stretches more than dry hair because water breaks hydrogen bonds; wet cutting therefore requires tension control to avoid overstretching.

Developer strengths: 10 volume = 3% hydrogen peroxide; 20 volume = 6%; 30 volume = 9%; 40 volume = 12%.

A patch test for aniline-derivative hair color is generally performed 24–48 hours before the service.

The color wheel neutralizes opposites: blue cancels orange, green cancels red, and violet cancels yellow.

Alkaline permanent waves using ammonium thioglycolate have a pH near 9.0–9.6; acid waves using glyceryl monothioglycolate have a pH near 6.5–7.5.

Sodium hydroxide relaxers are strongly alkaline (pH about 12–14) and straighten by breaking disulfide bonds; neutralization lowers pH and rebuilds bonds.

In a relaxer retouch, product is applied to new growth only; previously relaxed hair is protected to prevent overprocessing.

A strand test predicts processing time, lift, and damage risk before the full color or lightener service.

Metallic salts in hair can react unpredictably with lightener and color, causing breakage or discoloration; hair with metallic salt exposure requires caution.

Base color deposition uses 10-volume developer; higher volumes increase lift and are not used for deposit-only color.

Skin layers from outer to inner are epidermis, dermis, and subcutaneous tissue; the epidermis has no blood vessels.

The acid mantle pH is about 4.5–5.5 and supports barrier function and microbial balance.

Fitzpatrick types I–VI classify burning and tanning response; type I burns easily and tans minimally, while type VI rarely burns and tans deeply.

ABCDE melanoma warning signs: Asymmetry, Border irregularity, Color variation, Diameter greater than 6 mm, Evolving.

Alpha hydroxy acids such as glycolic and lactic acid are water soluble and work at the surface; salicylic acid is oil soluble and penetrates pores.

Waxing is contraindicated on inflamed, broken, sunburned, or retinoid-treated skin because the skin may tear.

Facial massage generally follows muscle fibers and lymphatic drainage with light upward and outward strokes.

Extractions are performed only on closed comedones or pustules with a visible opening, not on inflamed cystic lesions or unknown growths.

SPF 30 blocks about 97% of UVB radiation; SPF 50 blocks about 98%.

The nail plate is made of keratin and has no nerves or blood vessels; it grows from the matrix.

The matrix produces the nail plate and determines thickness and shape; the lunula is the visible part of the matrix.

Fingernails grow about 3.5 mm per month; toenails grow about 1.5 mm per month.

Nail shapes include square, squoval, oval, round, and pointed; shape choice follows the natural nail and client preference.

Onychomycosis is a fungal nail infection with thickening, discoloration, and separation; it requires medical referral, not a manicure.

Paronychia is inflammation or infection of the nail fold, often after cuticle damage; red, swollen, painful tissue is a contraindication for service.

Nonporous implements can be cleaned and disinfected; porous items such as wooden sticks, cotton, and some files cannot be effectively disinfected and are discarded.

Acrylic systems use a liquid monomer and powder polymer; the bead ratio affects strength, set time, and adhesion.

Base coat protects the nail plate and improves adhesion; top coat seals the color and adds gloss.

Sanitation removes visible debris and reduces microorganisms; disinfection kills most pathogens on nonporous surfaces; sterilization destroys all microbial life including spores.

Use an EPA-registered hospital-grade disinfectant at the label dilution and contact time for implements and surfaces.

Blood and body-fluid spills require gloves, absorbent removal, cleaning, and disinfection with an EPA-registered hospital disinfectant following label directions.

Porous items such as wood sticks, cotton, and some files cannot be adequately disinfected and must be discarded after use.

Handwashing with soap and water for at least 20 seconds is required before and after client services and after removing gloves.

A Safety Data Sheet provides hazard, handling, storage, and emergency information for each chemical product and must be accessible.

Electrical safety includes unplugging tools by the plug, avoiding water contact, and checking cords for damage before use.

Pathogens include bacteria, viruses, fungi, and parasites; hepatitis B and HIV are bloodborne pathogens.

Do not double-dip implements or reuse disposable items; single-use items are discarded after one client.