NBTE Cosmetology NID key terms

The use of chemical agents to destroy most pathogenic microorganisms on tools and surfaces, except bacterial spores. It follows cleaning and precedes reuse of implements in the salon.

A process that destroys all microorganisms including bacterial spores, usually by autoclave, dry heat or approved chemical soak. Required for items that may contact broken skin or blood.

The lowest level of hygiene control: washing with soap or detergent and water to physically remove dirt, oils and many microorganisms from hands, linens and general surfaces.

The transfer of microorganisms from one person, tool or surface to another, for example by reusing an unwashed brush or sharing a towel between clients. Prevented by single-use items and correct disinfection.

Any condition, medication or circumstance that makes a treatment unsafe or inadvisable for a client, such as active infection, open wounds or recent cosmetic surgery. It must be identified at consultation and the service declined or modified.

A small controlled application of a product on a discreet area of skin, usually 24 to 48 hours before service, to detect allergic reaction. Mandatory for many tinting and colour products.

An immune response to a substance such as a hair dye, adhesive or latex glove, producing redness, swelling, itching or breathing difficulty. It worsens with repeated exposure and requires referral.

The process by which repeated contact with an allergen, such as paraphenylenediamine in hair colour, gradually triggers an allergic response. A client may react even after years of previous safe use.

The structured pre-service interview and assessment in which the practitioner records client history, examines skin, hair and nails, agrees the service plan and identifies contraindications before any product is applied.

Visual and tactile assessment of the client's skin to determine type, condition, hydration and sensitivity, guiding the choice of cleansers, exfoliants and massage products for facial treatments.

A six-point classification of skin phototype based on colour and response to ultraviolet light, used to predict burning and tanning risk and to guide safe use of light-based and exfoliating treatments.

The study of the structure of the human body, including bones, muscles, nerves and blood vessels. Cosmetologists need it to work safely on the face, scalp, hands and feet.

The study of how body systems function, such as circulation, lymph drainage and skin renewal. It underpins safe massage, waxing and skin care decisions.

The outermost, avascular layer of the skin, composed mainly of keratinocytes. It provides the barrier against water loss and infection and is the layer most affected by exfoliation and superficial peels.

The middle layer of the skin, containing collagen, elastin, blood vessels, nerves, glands and hair follicles. It supports the epidermis and is the target of deeper treatments such as needling.

The outermost sub-layer of the epidermis, made of flattened dead keratinised cells. Its thickness and hydration determine how well products penetrate and how often the skin should be exfoliated.

The main structural protein of the dermis, giving skin strength and firmness. Production declines with age and ultraviolet exposure, which contributes to lines and sagging.

A resilient protein fibre in the dermis that allows skin to stretch and spring back. Damage from sun exposure and ageing reduces elasticity and causes looseness.

Gentle rhythmic massage movements that follow the direction of lymph flow toward lymph nodes, used to reduce puffiness and support removal of fluid and waste from facial tissues.

A smooth, gliding massage stroke performed with relaxed hands in the direction of muscle fibres or lymph flow. It is used to apply product, warm tissue and begin or end a massage sequence.

A group of kneading, rolling and squeezing massage movements that compress and lift soft tissue. It relaxes muscles and stimulates circulation and is applied after effleurage.

A brisk, rhythmic percussion movement using the fingertips, palms or the sides of the hands, performed at the end of a massage to stimulate circulation and tone tissue.

The first step of any facial or nail service, removing makeup, oil, dirt and surface microorganisms with an appropriate cleanser and water or cotton pad, using gentle upward movements.

Removal of dead cells from the skin surface by mechanical means such as scrubs and brushes, or chemical means such as alpha-hydroxy acids, to smooth and brighten the skin.

Application of a lotion after cleansing to remove residual cleanser, restore the skin's slightly acidic pH and refresh the skin before moisturising and massage.

A product that reduces water loss from the skin by forming a barrier or attracting water into the epidermis. It is the final step of most facial treatments.

The arrangement of a hair into cuticle, cortex and medulla, with the follicle and bulb at the root. Cuticle condition determines shine, porosity and how colour and chemicals behave.

The ability of hair to absorb and retain moisture, determined by the tightness of the cuticle. High porosity absorbs quickly but loses moisture fast and needs gentler chemical services.

The ability of wet hair to stretch and return to its original length without breaking. Poor elasticity indicates damage and warns against strong chemical processing.

The repeating phases of anagen (growth), catagen (transition) and telogen (rest and shedding) through which every follicle passes. Understanding it explains hair loss patterns and the limits of scalp treatments.

A small controlled application of a product on a discreet area of skin, usually 24 to 48 hours before service, to detect allergic reaction. Mandatory for many tinting and colour products.

Paraphenylenediamine, the primary dye intermediate in permanent hair colour. It requires developer to oxidise and is a common cause of severe allergic reaction, so patch testing is essential.

A hydrogen peroxide solution that, when mixed with colour or lightener, opens the hair cuticle and oxidises dye to develop colour. Its strength (volume) controls lift and deposit.

A small test on a hidden section of hair to check how colour, lightener or relaxer will perform on that client's hair before the full service. It predicts timing, result and damage risk.

A strongly alkaline cream that straightens curly or textured hair by breaking disulphide bonds in the cortex. It requires careful timing, scalp protection and neutralising to stop the reaction.

A product applied after relaxing or perming that lowers pH and rebuilds the disulphide bonds in the hair, fixing the new shape and preventing further processing damage.

The structure of the nail unit: nail plate, nail bed, matrix, cuticle, eponychium, lunula and free edge. Knowing it guides safe filing, cuticle work and detection of disorders.

The living tissue at the base of the nail where new cells are produced. Damage to it causes permanent ridges or distortion of the growing nail plate.

The thin non-living layer of skin that seals the base of the nail plate. It protects against infection and should be softened and gently pushed, never cut aggressively.

The living fold of skin at the base of the nail that produces the cuticle. Because it is living tissue, it must not be cut during manicure or pedicure.

The pale half-moon visible at the base of the nail, formed by the front part of the matrix. Changes in its colour or shape may indicate systemic or local disease.

A fungal infection of the nail plate and bed causing thickening, discolouration and crumbling. It is contagious and a contraindication for nail services; the client must be referred.

Inflammation or infection of the tissue around the nail, often from torn cuticles or aggressive cuticle work, producing redness, swelling and pain. Service must be withheld until resolved.

The set of practices, including handwashing, tool disinfection, clean linens and covered waste, that prevent the spread of infection between clients and between client and practitioner.

Temporary hair removal by applying warm or hot wax to the skin and removing it against the direction of hair growth. It requires skin assessment, patch testing and hygiene controls.

A hair removal technique in which twisted cotton thread is rolled over the skin to catch and lift hairs at the follicle, commonly used on eyebrows and the upper lip.

Cosmetic products applied to enhance or alter appearance, including foundation, concealer, powder, eyeshadow, liner, mascara and lip colour. Hygiene and correct colour matching are essential.

The principles of primary, secondary and complementary colours used to select makeup shades, neutralise skin tones and correct unwanted hues in hair colour.

Designing the workspace and working posture to reduce strain, for example adjusting chair and bed height, keeping wrists neutral and taking breaks. It prevents occupational injury in the salon.