KS Cosmetology key terms

The use of a chemical product registered by the EPA to destroy most pathogenic organisms on nonporous implements and surfaces, except bacterial spores. It is the required level of control for tools such as combs, shears, and clipper blades after each client.

The complete destruction of all microbial life, including bacterial spores, usually achieved with an autoclave using steam under pressure. It is the highest level of infection control and is required for items that may contact broken skin or blood.

The lowest level of infection control: cleaning surfaces and tools with soap, water, and detergents to physically remove dirt, oils, and a large number of microbes. Sanitation alone does not kill pathogens and must precede disinfection.

A hospital-grade or salon disinfectant carrying an EPA registration number and label directions for dilution, contact time, and safe handling. Only products with proven efficacy against the organisms named on the label may be used on salon implements.

The number of minutes an implement must stay fully submerged in or wet with disinfectant for the product to work as labeled. Cutting contact time short allows surviving organisms to remain and is a common inspection violation.

A standard of practice in which every client is treated as potentially infectious and gloves, barriers, and hand washing are used consistently. It removes the need to guess who carries a bloodborne pathogen such as hepatitis B or HIV.

Disease-causing microorganisms carried in blood or other body fluids, including hepatitis B, hepatitis C, and HIV. Exposure can occur through cuts, shaving nicks, or blood on nippers and must be handled with gloves and an EPA-registered hospital disinfectant.

A document, now usually called a Safety Data Sheet under the OSHA Hazard Communication Standard, listing a product's hazards, safe handling, first aid, and disposal. Salons keep these on file for every chemical used, such as relaxers, bleach, and acrylic monomer.

The number of individual hairs per square inch of scalp, described as thin, medium, or thick. Density differs from texture and determines how much hair is available for volume, layering, and styling choices.

The ability of the hair cuticle to absorb and hold moisture, rated as low, normal, or high. High porosity from cuticle damage takes color quickly but fades fast; low porosity resists penetration and may need heat or longer processing.

The hair's ability to stretch and return to its original length without breaking, indicating cortical strength and moisture balance. Wet hair in a healthy state stretches about 50 percent of its length before returning.

The outermost overlapping, scale-like layer of the hair shaft that protects the inner layers and controls how much moisture and chemical product enters. Rough or lifted cuticle causes dullness, tangling, and uneven color results.

The thick middle layer of the hair shaft that holds most of the fiber's strength, elasticity, melanin, and moisture. All permanent color, lightening, and texture changes take place chemically within the cortex.

The pigment produced by melanocytes in the hair bulb that gives hair its natural color. Eumelanin supplies brown and black tones while pheomelanin supplies red and yellow tones, and their ratio determines the natural level and underlying pigment.

The five chemical elements found in hair: carbon, oxygen, hydrogen, nitrogen, and sulfur. Sulfur forms disulfide bonds between protein chains, which is why wet hair smells and why those bonds can be broken and rebuilt during texture services.

A strong chemical bond linking two sulfur atoms in adjacent protein chains, giving hair much of its strength and shape. Permanent waves break these bonds and re-form them around a new shape; relaxers do the same to straighten.

A scale from 0 to 14 measuring acidity and alkalinity, with 7 neutral, below 7 acidic, and above 7 alkaline. Hair and skin are mildly acidic near pH 4.5 to 5.5, and alkaline products open the cuticle to allow chemical penetration.

An oxidizing agent used with permanent color and lightener to develop color and lift natural melanin, supplied in volumes such as 10, 20, 30, and 40. Higher volumes release more oxygen and produce more lift plus more damage.

The strength of hydrogen peroxide expressed in volume, where 20 volume is about 6 percent peroxide. Ten volume deposits color with minimal lift, while 40 volume lifts several levels and is limited to off-scalp use.

The warm pigment remaining in the hair after natural melanin is lightened, usually red, orange, or yellow depending on the starting level. It must be neutralized with a complementary tone or it will show through the finished color.

A semipermanent or demi-permanent color applied after lightening to refine or neutralize unwanted warmth and adjust the final reflect. Toners are usually low-volume and are chosen by the level and underlying pigment of the pre-lightened hair.

A small amount of color, lightener, or other chemical product applied to skin, typically behind the ear or in the elbow crease, 24 to 48 hours before the service. It screens for an allergic reaction that may not appear on a previous exposure.

A test on a small section of the client's hair, using the intended product and timing, to predict color, lightening, or curl results before full application. It reveals porosity issues, previous chemical history, and how much processing time is needed.

The active reducing agent in most alkaline permanent waves and in some depilatories, which breaks disulfide bonds so hair can be reshaped. It requires a neutralizer to rebuild the bonds and must never contact the eyes.

The oxidizing solution, usually hydrogen peroxide based, applied after a permanent wave or relaxer to rebuild disulfide bonds in the new shape. Incomplete neutralization leaves the hair weak, limp, or overprocessed.

A strong alkaline product, typically sodium hydroxide or guanidine hydroxide, that straightens overly curly hair by breaking disulfide bonds. Because it is caustic, it is applied to new growth only and requires a base and careful scalp protection.

A protective ointment applied along the hairline, ears, and scalp before a relaxer to shield skin from chemical burns. It is not a substitute for careful application but reduces irritation during the service.

A check during a permanent wave in which a rod is unwound slightly to see whether the desired S-shape has formed. It determines when to rinse and prevents underprocessing or overprocessing, especially on resistant or porous hair.

The angle at which a section of hair is held away from the head before cutting, measured from 0 to 90 degrees and beyond. Elevation controls where weight builds and how layered or graduated the finished shape becomes.

The first cut section that establishes the length and shape for the rest of the haircut. Also called the guide, it may be stationary for uniform cuts or traveling for graduated and layered shapes.

A one-length haircut made with zero elevation, cutting straight across the ends so all hair falls to the same level. It creates a solid perimeter and maximum weight at the bottom, and is often used as a base for other shapes.

A texturizing technique in which the tips of the shears are used to snip into the ends of a section, softening the line and reducing bulk. It is performed on the inside of the section and works best on dry or slightly damp hair.

Shaping and smoothing damp hair with a hand-held dryer and a round or paddle brush to create volume, direction, or a smooth finish. Sectioning, tension, and nozzle angle control the final movement and shine.

A product or technique that reduces heat damage from dryers, flat irons, and curling irons, usually by adding a film or moisture-binding ingredient. It is paired with temperature control, since irons above roughly 450 degrees Fahrenheit can permanently damage hair.

The visible hard keratin structure covering the nail bed, growing from the matrix and protected by the cuticle. Its condition reveals health, and its free edge is the part shaped during a manicure.

The area beneath the proximal nail fold where new nail cells are produced and keratinized. Damage to the matrix causes ridges, thinning, or permanent distortion of the growing nail plate.

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

A structured skin service including analysis, cleansing, exfoliation, extractions when appropriate, massage, mask, and moisturizer. Each step is selected for the client's skin type and condition, and contraindications are checked first.

The classification of skin as normal, dry, oily, or combination based on oil production and moisture balance. Skin type guides product selection, while skin conditions such as acne or dehydration are treated separately.

The removal of comedones and congestion from pores during a facial, using gentle pressure with fingers wrapped in tissue or a comedone extractor. It is performed only on suitable skin after softening and is skipped over inflamed acne.

The deeper layer of skin containing blood vessels, nerves, glands, hair follicles, and collagen and elastin fibers. It supplies the epidermis with nutrients and houses the structures that facials and massage affect.

The outermost, avascular layer of skin that constantly renews itself and provides the first barrier against moisture loss and infection. Its basal layer produces new cells that migrate upward and eventually shed.

The tube-shaped pocket in the dermis from which a hair grows, containing the bulb, root, and sebaceous gland attachment. Its shape determines whether hair is straight, wavy, or tightly coiled.