TN Cosmetology key terms

A process that uses chemicals to destroy most disease-causing microorganisms on hard, nonporous surfaces and implements, though not bacterial spores. Tools must be cleaned of debris first, then soaked for the full contact time stated on the product label.

The complete destruction of all microbial life, including bacterial spores, on an object. Salons rarely need it and usually rely on prepackaged single-use sterile items such as needles rather than performing sterilization in-house.

A product with an EPA registration number that is labeled as effective against a broad range of bacteria, fungi, and viruses. Salons must use one approved under state rules and mix or replace it according to label directions.

An infection-control approach in which every client's blood and body fluids are treated as potentially infectious. It means wearing gloves, using barriers, and following disinfection routines regardless of how healthy a client appears.

A standardized document from a product manufacturer listing a chemical's hazards, safe handling steps, first-aid measures, and spill procedures. Salons must keep these sheets on site and accessible for every professional product used.

A material such as a cotton towel, wooden stick, or porous nail file that absorbs liquids and cannot be reliably cleaned and disinfected. Such items are discarded after one use or, when washable, laundered properly.

A scale from 0 to 14 that measures how acidic or alkaline a substance is, with 7 being neutral. Hair and skin are mildly acidic, and products far outside that range can swell the cuticle or strip color.

The thick middle layer of a hair strand, built from elongated keratinized cells. It holds the pigment melanin and the side bonds that give hair strength, elasticity, and curl, so coloring and texture services act mainly here.

The tough outer layer of a hair strand, made of flat overlapping transparent cells. When it lies flat, hair looks smooth and shiny; when it is raised or damaged, hair feels rough, tangles, and loses moisture quickly.

The active growth stage of the hair growth cycle, when cells in the follicle divide and a new hair is pushed upward. It lasts roughly two to seven years and determines how long an individual hair can grow.

A contagious fungal infection of the nail plate and nail bed that can cause thickening, discoloration, and lifting of the nail. A cosmetologist should not perform nail services on an affected nail and should refer the client to a physician.

The natural pigment produced by melanocytes that gives hair, skin, and eyes their color. The amount and blend of its types determine whether a person's hair coloring is black, brown, red, or blonde.

A chemical reaction in which oxygen is added to a substance or hydrogen is removed from it. In hair services, oxidation is what develops color and lightens pigment when hydrogen peroxide is mixed with dye or lightener.

The angle at which a strand of hair is held away from the head before it is cut. It controls how layers relate in length, with 0 degrees building weight and 90 degrees producing uniform, even layers.

Combing a section of hair away from its natural fall position before cutting, usually to build length or weight toward one side of the head. It is often used to blend a shorter side into a longer one.

The first strand cut in a subsection, which sets the length and shape that the remaining strands in that area will follow. Also called a guide, it may stay in place or move as the section progresses.

Re-cutting a finished section at a right angle to the original cutting lines to reveal uneven strands or hairs that were missed. It is a final quality-control step that improves the precision of the finished shape.

A styling method in which damp hair is wrapped on rollers or shaped into finger waves and then dried under a hood, so the hair holds a temporary curl or wave pattern until the next shampoo.

Roller placement in which the roller sits directly on top of its base section, producing the strongest, longest-lasting curl and the most lift at the scalp. It is also called full-base placement.

Teasing or combing hair from the ends toward the scalp to build a matted cushion at the base of the strand. It adds volume and support for updos but can rough up the cuticle if done too aggressively.

An electric styling tool with a heated barrel that temporarily reshapes hair into curls, waves, or bends. Barrel size controls the diameter of the curl, and the tool should be used on dry hair with heat protection.

A liquid that supplies oxygen to break down color molecules and, when mixed with dye or lightener, drives the coloring or lightening process. Its strength, measured in volume, determines how much lift occurs.

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

A test in which a small section of the client's hair is treated with the chosen formula to preview timing, color result, and condition. It is especially useful on resistant, previously colored, or highly porous hair.

A sheer color applied after lightening to cancel unwanted warmth and refine the final shade. It adds little depth and sits mostly on the surface, so it fades faster than permanent color.

A numbering scale, usually 1 through 10, describing how light or dark a hair color is, from black to lightest blonde. Level describes lightness only, while the tone describes whether the shade is warm, cool, or neutral.

A chemical cream that breaks the disulfide bonds in curly or coarse hair so it can be straightened and reshaped. Hydroxide and thio types differ in strength, processing method, and how much scalp protection is required.

A low-pH shampoo used after a thio relaxer or permanent wave to stop chemical processing and rebuild disulfide bonds. It must be worked through thoroughly to return the hair to its natural pH.

A small curl processed during a permanent wave to check how the hair is responding before the full processing time is applied. It shows whether the wave pattern is forming properly and helps prevent over-processing.

A thick, oil-based product applied along the scalp and hairline before a relaxer to shield skin from chemical burns and irritation. It is placed carefully between the parts without being rubbed into the scalp.

The visible, hardened keratin structure that covers the nail bed and protects the tip of the finger or toe. Its thickness, surface, and color give clues about the client's health and about service safety.

The living band of skin at the base of the nail plate that seals the area where skin meets nail. It should be gently pushed back but never cut, because cutting it opens a path for infection.

A continuous, gliding massage stroke that follows the direction of the muscle fibers or moves toward the heart. It is used to open and close a facial or hand massage and helps relax the client and warm the skin.

Removal of comedones or built-up congestion from the pores, usually after softening the skin with steam. The esthetician uses proper technique and avoids inflamed or infected areas, which should be referred to a physician.

The specific services and duties a licensee is legally allowed to perform under a state license. Working outside that boundary, such as diagnosing or treating a medical condition, can bring discipline from the board.

Ongoing training hours a licensee must complete during each renewal period to keep a license active. The required hours and approved subject areas are set by the state board and vary by license type.

An arrangement in which a licensed professional rents space in a salon and runs an independent business, keeping their own client records and paying their own taxes. The salon owner still enforces sanitation and facility rules.

Explaining a service, its risks, expected results, and alternatives, then getting the client's agreement before starting. It matters most for chemical services, skin treatments, and any procedure that could cause a reaction.