CO Cosmetology key terms

A process that uses chemicals registered by the EPA as hospital-strength disinfectants to kill most bacteria, fungi, and viruses on nonporous implements after they have been cleaned. It does not kill bacterial spores.

A process that completely destroys all microbial life, including bacterial spores, on an object. In salons it is reserved for items that contact broken skin or are exposed to blood, and requires an autoclave or approved sterilant.

The lowest level of infection control: washing with soap and water or using a detergent to physically remove dirt, debris, and many microbes from surfaces and hands. It is a cleaning step, not a germ-killing step.

A microorganism carried in blood or other body fluids that can cause disease when it enters the body, such as hepatitis B, hepatitis C, and HIV. Standard precautions treat all blood and body fluids as potentially infectious.

A document supplied by a product manufacturer that lists a chemical's hazards, safe handling and storage requirements, first-aid measures, and spill procedures. Employers must keep one accessible for every hazardous product in the salon.

A small amount of a product applied to a client's skin, usually behind the ear or in the elbow crease, and observed for 24 to 48 hours before a full service. It screens for allergic reaction to color, bleach, or adhesive.

A delayed skin reaction, appearing hours to days after exposure, in which the immune system becomes sensitized to an ingredient and responds with redness, itching, swelling, or blisters. Once sensitized, a client reacts on every future exposure.

A class of dye chemicals, including PPD and PTD, used in oxidative hair color and some temporary colors. They can cause severe allergic reactions and are the usual reason a patch test is required before coloring.

The ability of hair to absorb and retain moisture, determined by the condition of the cuticle. Low porosity resists absorption, while high porosity absorbs quickly but loses moisture and color rapidly.

The ability of wet hair to stretch and return to its original length without breaking. Healthy hair stretches up to about half its length; poor elasticity signals damage and limits chemical services.

The outermost layer of the hair shaft, made of overlapping, scale-like cells that protect the inner layers. Lifting these scales allows color and lightener to enter; smoothing them adds shine and reduces frizz.

The middle and thickest layer of the hair shaft, containing keratin bundles and the melanin that gives hair its color. Chemical services such as coloring, relaxing, and perming act primarily on this layer.

Permanent hair color that requires a developer to lift the cuticle and deposit dye inside the cortex, producing lasting color. Because the cuticle is opened, a patch test and strand test are standard precautions.

A hydrogen peroxide solution mixed with permanent color or lightener to open the cuticle and activate the dye. Its volume strength controls how much lift is achieved, from gentle deposit to strong lightening.

A strong alkaline product, usually containing sodium hydroxide, lithium hydroxide, or guanidine, that breaks the side bonds in hair to straighten curl. It requires careful scalp protection and is never applied over previously relaxed hair without analysis.

A test performed on a small section of the client's hair before a chemical service to predict how the hair will respond and to time the product correctly. It reduces the risk of overprocessing and uneven results.

Damage caused by leaving a chemical product on the hair too long, using too strong a formula, or repeating a service too soon. Signs include excessive porosity, poor elasticity, breakage, and a gummy wet texture.

The direction in which hair grows from the scalp, including whorls and cowlicks. It determines how the hair falls and where a cut or style must be adapted to prevent gaps or unruly sections.

The first cut strand or section in a haircut that establishes the length and angle all other sections are matched to. Also called a guide or baseline, it controls the overall shape of the finished cut.

The angle at which hair is held away from the head while cutting, measured from the scalp. Low elevation builds weight, medium elevation creates layers, and high elevation removes weight and adds movement.

Dividing the hair into clean, controlled subsections with clips or ties before cutting, coloring, or styling. Consistent sectioning keeps work organized, balances both sides, and prevents missed strands.

A cutting technique in which a straight razor slices hair at an angle to create soft, tapered ends and texture. It demands light pressure and tension control because a dull or angled blade can fray and damage ends.

Any technique that removes bulk or creates movement within a haircut, such as point cutting, notching, slicing, or thinning shears. It is done after the basic shape is established and should blend invisibly.

A gradual shortening of hair length toward the neckline or around the ears, creating a soft transition between longer and shorter areas. It is a defining feature of classic men's cuts and many short women's styles.

A structured visual and tactile assessment of a client's skin before treatment, noting skin type, oiliness, pore size, texture, and any lesions or contraindications. Findings determine which products and services are safe and appropriate.

A six-level classification of skin response to ultraviolet light, from very fair skin that always burns to deeply pigmented skin that rarely burns. It guides sun-protection advice and the safe use of light-based treatments.

A condition or circumstance that makes a service inadvisable or unsafe for a client, such as open lesions, active infection, recent surgery, or a known allergy. Identifying it protects both client and practitioner.

The removal of dead cells from the skin's surface by mechanical scrubbing or chemical agents such as alpha hydroxy acids. It improves texture and product absorption but requires sun protection and caution on sensitive skin.

Manual removal of comedones or pustules from pores using gloved fingers or a sterile extractor after softening the skin. It is limited to non-inflamed lesions and requires proper technique to avoid scarring or infection.

An oily substance produced by the sebaceous glands that lubricates skin and hair and helps retain moisture. Excess sebum contributes to oily skin, clogged pores, and acne, while too little causes dryness.

A plugged hair follicle formed when sebum and dead cells block a pore. An open comedone is a blackhead; a closed comedone is a whitehead beneath the skin surface.

The visible, hardened keratin structure covering the nail bed, extending from the matrix to the free edge. Its condition reflects health, and it must be shaped and treated gently to avoid splitting and lifting.

The living area at the base of the nail where new cells are produced and keratinized. Damage to the matrix permanently affects the shape and thickness of the growing nail plate.

The skin beneath the nail plate, rich in blood vessels, which supports the plate and appears pink through it. Injury here can cause discoloration or separation of the plate.

The thin layer of dead tissue that seals the base of the nail plate where it meets the skin. It protects against infection and should be softened and gently pushed back, never cut deeply.

A fungal infection of the nail, appearing as thickened, discolored, crumbly, or separating nail plate. It is contagious and is a contraindication for nail services; clients should be referred to a physician.

A solution applied to the natural nail plate before acrylic or gel to remove surface oils and improve adhesion. Some primers contain methacrylic acid and must be kept off skin and used with ventilation.

The transfer of microbes from one person or object to another through shared tools, hands, or surfaces. It is prevented by handwashing, using fresh implements or disinfecting between clients, and never double-dipping.