PA Cosmetology key terms

The outermost layer of the hair shaft, made of overlapping, transparent scales that protect the inner layers and control how easily hair absorbs moisture.

The middle and thickest layer of the hair shaft. It gives hair its strength, elasticity, and natural color because it contains the melanin pigment.

A strong protein that makes up most of the hair, skin, and nails. Chemical services work by changing the bonds that hold keratin fibers together.

A strong chemical bond that links sulfur atoms in neighboring keratin fibers. Permanent waves and relaxers break these bonds and then re-form them to change hair shape.

The ability of hair to take in and hold moisture. Hair with high porosity absorbs quickly but loses moisture fast, while low porosity resists absorption.

The ability of hair to stretch and return to its original length without breaking. Good elasticity usually means hair is healthy and strong.

A scale from 0 to 14 that measures how acidic or alkaline a substance is. Seven is neutral, and hair and skin are happiest in the slightly acidic range.

A test done on a small section of hair before a color, perm, or relaxer service to predict how the hair will react and to choose the right timing.

A test in which a small amount of product is applied to the skin, usually behind the ear or on the inner arm, 24 to 48 hours before a service to check for an allergic reaction.

A hydrogen peroxide solution mixed with hair color to start the oxidation process that creates color and, in some products, lifts or lightens the natural pigment.

An oily substance produced by the sebaceous glands in the skin. It lubricates the skin and hair and helps hold moisture in.

The outermost layer of the skin. It has no blood vessels, is made of cells that constantly shed and renew, and acts as the body's first barrier.

The layer of skin beneath the epidermis. It contains blood vessels, nerves, glands, and hair follicles, and it supports and feeds the epidermis.

The very top layer of the epidermis, made of flattened dead skin cells. It protects the living layers below and is what exfoliation removes.

The natural pigment produced by cells called melanocytes. It gives skin, hair, and eyes their color and helps protect skin from ultraviolet light.

A scale that groups skin into six types based on how it responds to sun exposure and how easily it burns or tans. Estheticians use it to plan safe treatments.

Describes a product or ingredient that tends to clog pores and can lead to blackheads or acne. Estheticians choose non-comedogenic products for acne-prone clients.

The process of removing dead cells from the surface of the skin. It can be done with physical scrubs or chemical products and leaves skin smoother and brighter.

A condition, medication, or situation that makes a service unsafe for a client. Examples include skin infections, open cuts, or recent cosmetic surgery.

The visible, hard part of the nail made mostly of keratin. It sits on the nail bed and protects the sensitive tissue beneath it.

The area at the base of the nail where new nail cells are made. It is responsible for the growth of the nail plate and lies under the eponychium.

The whitish, half-moon shape seen at the base of the nail. It is the visible part of the matrix where new nail cells are forming.

The living skin at the base of the nail that overlaps the nail plate. It seals the nail area and should never be cut during a manicure.

A fungal infection of the nail that can cause thickening, discoloration, and separation of the nail plate. It is contagious and a reason to refer a client to a doctor.

An infection of the skin around the nail, often caused by bacteria entering through a cut or torn cuticle. It causes redness, swelling, and pain.

The liquid part of a liquid-and-powder nail enhancement system. It reacts with the powder to form a hard acrylic that shapes and strengthens the nail.

The powder part of a liquid-and-powder nail enhancement system. When mixed with monomer it forms the acrylic that hardens into the sculpted nail.

The process of killing most harmful microorganisms on surfaces and tools, except bacterial spores. It is done with an EPA-registered product after items are cleaned.

The process that destroys all microorganisms, including bacterial spores. Autoclaves are used for items that must be completely free of germs.

The first step of cleaning, which removes visible dirt, debris, and many germs from surfaces and tools. It is done before disinfection or sterilization.

A disinfectant that has been reviewed and approved by the Environmental Protection Agency for killing germs. Salons must use one that is labeled for hospital or salon use.

A document provided by the manufacturer that lists a product's ingredients, hazards, safe handling, and first-aid steps. Salons must keep one for every chemical product they use.

Disease-causing microorganisms carried in blood, such as hepatitis B and HIV. They can be spread through cuts or needle sticks, so workers follow standard precautions.

The spread of germs from one person, tool, or surface to another. It happens when clean and dirty items are mixed or hands and tools are not sanitized between clients.

A material that absorbs liquids, such as a cotton towel, sponge, or wooden file. Porous items cannot be fully disinfected and should be thrown away after one client.

The Pennsylvania agency that licenses and regulates cosmetologists, estheticians, nail technicians, and salons, and that enforces the state's cosmetology laws and rules.

The set of services and tasks a licensed professional is legally allowed to perform. Doing work outside that scope can lead to discipline or loss of license.

A way for a licensee from another state to get a Pennsylvania license based on their existing credential, usually when the other state's requirements are comparable.

The license a salon must hold to legally offer cosmetology services in Pennsylvania. It is separate from the individual licenses held by the people working there.

Performing cosmetology services without a valid license or while a license is expired or suspended. It is illegal and can result in fines and other penalties.