KY Cosmetology key terms

The scientific study of the hair and its disorders, covering structure, growth cycles, and the conditions that affect the follicle and shaft.

The active growth stage of the hair cycle, when cells in the follicle divide rapidly and new hair is produced. It lasts several years and determines hair length.

The short transitional stage of the hair cycle in which growth stops and the follicle begins to shrink and detach from the hair root.

The resting stage of the hair cycle, when the fully formed hair stays in the follicle until it is pushed out by new growth and sheds.

The three concentric parts of a hair: the medulla at the core, the cortex containing pigment and strength, and the cuticle, the outer protective scale layer.

The middle, thickest layer of the hair shaft, made of elongated cells holding melanin. It gives hair its strength, elasticity, and natural color.

The outermost layer of the hair shaft, formed of overlapping transparent scales that protect the cortex and control moisture loss and chemical penetration.

The pigment produced in the hair follicle that gives hair its natural color. Its type and amount determine whether hair is black, brown, red, or blonde.

The ability of the hair cuticle to absorb and hold moisture. Low porosity resists absorption, while high porosity absorbs quickly and loses moisture easily.

The ability of dry hair to stretch and return to its original length without breaking. It indicates the strength of the cortex and overall hair health.

A measure from 0 to 14 of how acidic or alkaline a substance is. Hair and skin are mildly acidic, and products outside that range can alter the cuticle.

A shampoo formulated near the natural pH of hair and skin, usually around 4.5 to 5.5. It cleans gently while helping the cuticle lie flat and stay smooth.

A strong chemical bond between sulfur atoms in the cortex that holds hair in its shape. Permanent waves and relaxers break and reform these bonds.

Protecting the client and the work area with a cape, towel, and neck strip before a service. Proper draping keeps products off clothing and skin.

A narrow disposable strip placed between the client's skin and the cape to prevent hair and products from touching the neck and to keep the cape clean.

A protective cloth or plastic covering fastened around the client's shoulders during hair services to keep clothing and skin free of water and chemicals.

Cleansing the hair and scalp with water and a surfactant product to remove oil, dirt, and product buildup before cutting or chemical services.

A product applied after shampooing that smooths the cuticle, adds moisture and protein, and reduces tangling, making hair easier to comb and style.

Dividing the hair into controlled, even parts with clips before cutting, coloring, or styling so each area is worked consistently and symmetrically.

The angle at which hair is held away from the head while cutting. It controls the amount of layering and where the length falls in the finished style.

The first cut section that sets the length and shape for the rest of the haircut. All following sections are matched to it for balance.

Shaping and drying damp hair with a hand-held dryer and a brush or comb to create volume, direction, and a smooth finish.

A hydrogen peroxide solution mixed with permanent or demi-permanent color to open the cuticle and develop the color molecules inside the cortex.

Color that enters the cortex and lifts natural pigment while depositing new color. It does not wash out, though roots require touch-ups as hair grows.

A small amount of color or chemical product applied to the skin, usually behind the ear or inner elbow, to check for an allergic reaction before a full service.

An alkaline or acid waving lotion that breaks disulfide bonds in the hair so it can be wrapped into a new curl shape, which is then fixed.

The second step of a permanent wave, a solution that rebuilds the disulfide bonds in their new curled position so the wave holds its shape.

A strong alkaline product, usually containing sodium hydroxide or a no-lye alternative, that straightens curly hair by breaking and reforming disulfide bonds.

A protective ointment applied along the hairline and around the ears before a relaxer service to shield the skin from irritation and chemical burns.

Examining a client's skin type, tone, and condition before a facial to choose appropriate products and identify areas that need special care or referral.

A professional skin treatment that cleanses, exfoliates, extracts, massages, and moisturizes the face and neck to improve and maintain skin health.

Removing blackheads and clogged pore contents with gentle pressure using the fingers wrapped in tissue or a sterile tool during a facial.

A condition that makes a service unsafe or inadvisable, such as broken skin, infection, or a recent chemical peel, requiring the service to be postponed or refused.

A temporary hair removal method in which warm or hard wax is applied over the skin, allowed to set, and removed against hair growth to pull hair from the follicle.

The visible, hard part of the nail made of keratinized cells that rests on the nail bed and protects the sensitive tissue beneath.

The skin layer directly beneath the nail plate that supplies it with nutrients and appears pink through the translucent plate.

The hidden area at the base of the nail where new cells are produced. It determines the thickness and shape of the growing nail plate.

A fungal infection of the nail that causes thickening, discoloration, and crumbling. It is contagious and must be referred to a physician, not treated in the salon.

Inflammation or infection of the skin around the nail, often red, swollen, and painful. Licensed professionals should not perform services on infected tissue.

Destroying most disease-causing microorganisms on nonporous tools and surfaces using an EPA-registered hospital-grade disinfectant at the correct dilution and contact time.

The complete destruction of all microbial life, including bacterial spores, usually achieved with an autoclave. It is the highest level of decontamination.

The lowest level of infection control: cleaning and reducing visible soil and some microorganisms on surfaces and tools, usually with soap and water.

Treating all blood and body fluids as potentially infectious and using gloves and other barriers for every client, regardless of known health status.

Barriers such as gloves, safety glasses, and aprons worn during services to protect the professional from chemicals, splashes, and infectious materials.

The services a licensed professional is legally permitted to perform under state law. Working outside it can lead to discipline or license loss.

The official credential granted by the state board after a candidate meets education, examination, and application requirements, allowing legal practice of cosmetology.

Required training hours a licensee completes to renew a license, keeping knowledge current on safety, technique, and changes in state law and rules.

The standards of honesty, confidentiality, and respect a professional follows with clients and coworkers, including informed consent and refusing unsafe or out-of-scope services.

The state rules covering salon licensing, sanitation standards, equipment, and record keeping that a salon must meet to operate lawfully and pass inspection.