Master Esthetician key terms

The outermost layer of the epidermis, made of flattened, keratin-filled cells that form the skin's primary barrier against water loss, irritants, and microbes; its condition strongly influences how much exfoliation or peel a client can safely tolerate.

The skin's ability to retain water and keep out irritants, allergens, and pathogens, maintained by corneocytes embedded in lipids. Compromised barrier function raises the risk of irritation, post-inflammatory hyperpigmentation, and adverse peel reactions.

The measurable amount of water that evaporates through the skin surface. Elevated values suggest a damaged barrier and are a useful objective indicator when deciding whether a client's skin is ready for aggressive exfoliation.

Describes an agent that softens and loosens the bonds between dead skin cells so they shed more readily. Alpha hydroxy acids, salicylic acid, and urea are common examples used in peels and exfoliating products.

The natural shedding of corneocytes from the skin surface. Exfoliating treatments accelerate this process, and understanding normal turnover helps the esthetician predict healing time and avoid over-exfoliation.

The time it takes for newly formed skin cells to migrate to the surface and shed. This rate slows with age and sun exposure, which is why mature or photodamaged skin often shows dullness and benefits from gentle exfoliation.

A water-soluble acid such as glycolic or lactic acid that exfoliates by weakening bonds between dead surface cells. Concentration, pH, and application time together determine its strength and irritation potential.

An acid, most commonly salicylic acid, that is lipid-soluble and thus penetrates oily follicles well. It is often chosen for acne-prone or oily skin and is used at lower concentrations than many alpha hydroxy acids.

A lipid-soluble beta hydroxy acid used to exfoliate inside pores and reduce comedones. Because it is related to aspirin, allergy screening is essential, and it is not appropriate for clients with known salicylate sensitivity.

A measure of acidity that strongly affects how aggressively an acid peel acts on skin. Lower pH generally increases free acid and penetration, so the esthetician must know both pH and concentration rather than concentration alone.

The portion of acid in a peel solution that is unbound and able to act on the skin, expressed as a percentage. It is a more meaningful predictor of peel strength than the total acid concentration printed on the label.

The process of raising a peel's pH to stop acid activity, typically with a basic solution. Knowing whether a peel is self-neutralizing or requires a neutralizing agent is essential to control depth and prevent burns.

A whitish appearance on the skin during a peel that signals protein coagulation and deeper acid penetration. It is a clinical endpoint that tells the esthetician to stop immediately and neutralize if the protocol requires it.

The level of skin reached by a peeling agent, described as superficial, medium, or deep. Depth determines expected downtime, risk of complications, and whether the treatment falls within an esthetician's legal scope of practice.

A resorcinol, salicylic acid, and lactic acid blend used as a superficial peeling agent or as a primer before other peels. Its resorcinol content requires caution and is restricted in some jurisdictions.

A mechanical exfoliation technique that projects abrasive crystals or a diamond-tipped handpiece across the skin to remove the outermost layers. It is used for texture, dullness, and mild pigmentation, with pressure and passes controlling intensity.

The suction setting on a microdermabrasion device that pulls skin against the handpiece and removes debris. Excessive suction increases abrasion depth and bruising risk, so it must be adjusted to the treatment area and skin type.

Removal of dead surface cells through physical means such as abrasion, scrubs, brushes, or dermaplaning rather than chemicals. Overuse can impair the barrier, so frequency and technique must be matched to the client's skin.

A manual exfoliation method using a sterile surgical blade to scrape away vellus hair and dead surface cells. It requires strict blade handling and hygiene, and is avoided on inflamed, broken, or actively acneic skin.

The principle that a light-based device can target a specific chromophore, such as melanin or hemoglobin, while limiting damage to surrounding tissue. It underpins the safe use of lasers and intense pulsed light in esthetics.

A molecule in skin that absorbs light at particular wavelengths, such as melanin, hemoglobin, and water. Matching a device's wavelength to the intended chromophore determines whether a treatment targets pigment, vessels, or texture.

A device that emits broad-spectrum, non-coherent light used for pigmentation, redness, and hair reduction. Because it is not a laser, its scattered wavelengths require careful client selection and conservative settings on darker skin.

A six-point classification of skin based on pigmentation and tanning response. It guides device settings, peel selection, and counseling about post-inflammatory hyperpigmentation risk in clients with more reactive melanin.

The pigment produced by melanocytes that gives skin, hair, and eyes their color and provides some protection from ultraviolet radiation. Its distribution and reactivity affect pigmentation outcomes after peels and light treatments.

Darkening of skin after inflammation or injury, common in clients with more reactive melanin. Aggressive exfoliation, improper technique, and unprotected sun exposure can all trigger or worsen it.

Skin changes caused by cumulative ultraviolet exposure, including wrinkles, laxity, uneven pigmentation, and textural roughness. It is a key treatment target for chemical peels, microdermabrasion, and light-based therapies.

The initial, characteristic skin change produced by a disease process, such as a macule, papule, vesicle, or nodule. Identifying it correctly is fundamental to skin analysis and to deciding whether treatment must be deferred.

A skin change that evolves from a primary lesion or results from scratching and healing, such as crust, scale, scar, or excoriation. Recognizing it helps the esthetician judge whether skin is intact enough for treatment.

A condition or circumstance that makes a treatment unsafe or inadvisable. Examples include active infection, recent isotretinoin use, open lesions, or pregnancy, depending on the modality, and each must be screened before service.

A small, controlled application of a product on a limited area to check for an adverse reaction before full treatment. It is especially useful for clients with known sensitivities or when introducing a new peel formulation.

An unwanted response to a chemical peel, such as excessive erythema, blistering, prolonged crusting, or infection. Prompt recognition, neutralization where appropriate, and referral to a medical professional limit harm.

The set of practices that prevent transmission of pathogens between clients and staff, including hand hygiene, surface disinfection, tool sterilization, and proper waste handling. It is a legal and ethical baseline for every esthetic service.

The practice of treating all blood, body fluids, and potentially infectious material as if they carry transmissible pathogens. Applying it consistently protects both the client and the practitioner regardless of known health status.

The safe handling and discarding of blades and needles into a rigid, puncture-resistant container immediately after use. Proper disposal prevents needlestick injuries and is required wherever dermaplaning or similar services are performed.

The treatments and procedures an esthetician is legally permitted to perform under state or regional licensing rules. Exceeding it, for example by performing medium-depth peels or laser treatments without authorization, carries legal risk.

A documented conversation in which the client receives clear information about a treatment's benefits, risks, alternatives, and aftercare, then agrees to proceed. It protects both client autonomy and the practitioner's professional standing.

A written or electronic account of the client's history, skin assessment, products used, settings, and outcomes. Accurate records support continuity of care and provide evidence if a reaction or dispute arises.