MD Barber key terms

Bacteria that can cause disease. They travel on hands, tools, linens, and water, so barbers remove them by cleaning thoroughly and then applying an EPA-registered disinfectant.

A dormant, hard-shelled form some bacteria take when conditions are harsh. Spores survive many disinfectants, so tools exposed to them require sterilization instead of routine disinfection.

A process that destroys all microorganisms, including spores, typically using an autoclave with steam under pressure. Barbers use it only for items that can tolerate heat and moisture.

A microscopic infectious agent that reproduces only inside a living host cell, causing illnesses such as hepatitis B and colds. It is unaffected by antibiotics, and only products labeled virucidal are expected to kill it.

A numbered scale from 0 to 14 that measures how acidic or alkaline a water-based solution is, with 7 being neutral. Hair and skin are mildly acidic, so strong products shift the scale and change how chemical services behave.

A major artery on each side of the neck that supplies blood to the head and face. Barbers avoid pressing on it and treat any cut in this area as a serious bleeding emergency.

The fifth cranial nerve, which carries sensation from the face and controls the muscles of chewing. Its branches run over the cheeks, nose, and jaw, so pressure and razor work there are kept light.

A broad, flat muscle covering the front of the neck and lower jaw. It tightens when the head is stretched for shaving, and it lies over vessels and nerves the barber must avoid cutting.

A tube-shaped pocket in the skin that holds the hair root and shapes the hair as it grows. Chemical services and infections such as folliculitis both involve the follicle, so its health matters.

The tough, overlapping outer layer of the hair shaft that protects the inner layers. It lifts during chemical services and rough handling, which makes hair feel rough and look dull.

The middle and thickest layer of the hair shaft, made of long cells that give hair strength, elasticity, and most of its color. Color and waving products work mainly in this layer.

The active growth stage of the hair cycle, when cells in the follicle divide and a new hair is pushed upward. Most scalp hairs are in this stage at any given time.

A small gland attached to the hair follicle that releases sebum, an oily substance that lubricates skin and hair. Overactivity contributes to an oily scalp and acne-like conditions.

The ability of the hair shaft to absorb and hold moisture, determined largely by the condition of the cuticle. Low porosity resists moisture, while high porosity absorbs quickly but loses it fast.

Partial or complete hair loss that may be temporary or permanent and can come from genetics, illness, medication, or harsh chemical treatment. Barbers recognize it and avoid services that could make it worse.

A fungal infection of the beard area and neck, sometimes called barber's itch, causing red, scaly, itchy patches around hairs. It is contagious, so tools must be disinfected and shaving avoided until it is treated.

The angle at which a section of hair is lifted away from the head before cutting. Low elevation builds weight, while high elevation removes weight and creates layers.

The direction in which hair is combed or parted before cutting, measured relative to the head. It controls where hair falls and how the finished style behaves.

The first cut section that sets the length against which other sections are measured. Also called a guide, it keeps the haircut balanced and even on both sides.

Recombing and lifting already cut hair in directions different from the original sections to find uneven spots. It confirms the cut is balanced before the client leaves the chair.

A cutting method in which the clipper runs along the top of a comb held in the hair, cutting hair to the comb's thickness. It blends short sides and builds tight tapers.

A haircut in which length blends gradually from very short at the skin or neckline to longer toward the top. Smooth blending requires steady clipper work and careful cross-checking.

A thick, wet foam of shaving soap or cream worked into the beard to soften hair, hold it upright, and let the razor glide. It also shields skin from irritation during the shave.

A razor stroke in which the barber's fingers rest on the skin and the hand moves freely, used on large flat areas such as the cheeks and jaw. The razor is drawn with light, even pressure.

A razor stroke made with the palm turned so the blade travels in the opposite direction from the freehand stroke. It is used on the neck and the far side of the face for a close shave.

Grinding a straight razor on a sharpening stone to restore its edge after the blade dulls or gets nicked. It shapes the bevel, and stropping afterward smooths the edge.

Drawing a sharpened straight razor across a leather strop to polish the edge and remove tiny burrs. It is done before each shave to keep the blade smooth and comfortable on skin.

Razor bumps that form when tightly curled hairs are cut short and grow back into the skin, causing irritation and small bumps. Barbers manage it with careful shaving direction and by avoiding repeated close passes.

A small amount of color or chemical product applied to skin, usually behind the ear or in the elbow crease, then checked 24 to 48 hours later for a reaction. It predicts allergic sensitivity before a full service.

A test on a few strands of the client's hair to see how a chemical product develops and how long it takes. It predicts timing, final result, and damage risk before full application.

A strong alkaline cream that straightens curly or tightly coiled hair by breaking bonds within the cortex. It requires careful timing, a protective base, and thorough rinsing to avoid scalp injury.

The step after relaxing or a permanent wave that stops the chemical action and fixes the hair into its new shape. It must be complete to prevent continued damage and breakage.

A chemical, such as ammonium thioglycolate, that breaks the disulfide bonds in hair so it can be reshaped around a rod or smoothed. It is the active ingredient in permanent waves and some relaxers.

A hydrogen peroxide solution that supplies oxygen to lighten the hair's natural pigment and to make permanent color form inside the cortex. Its strength is chosen by how much lightening is needed.

Treating cleaned tools and surfaces with an EPA-registered product that destroys most harmful microorganisms. It follows cleaning and, unlike sterilization, does not reliably kill spores.

Any contact with blood or another body fluid through a cut, nick, splash to the eyes, or broken skin. The barber stops the service, cleans up, reports it, and follows the shop's written plan.

A standardized document, formerly called an MSDS, listing a product's hazards, safe handling, and first-aid steps. Shops keep these sheets where employees can reach them for every chemical on site.

A tool or supply meant for one client only and then thrown away, such as a razor blade or neck strip. It is never reused or disinfected for another client.

The state body that licenses barbers and barber shops and enforces Maryland barbering statutes and sanitation rules. It inspects shops and may fine, suspend, or revoke a license.