BM Coiffure key terms

A numbered scale from 0 to 14 that measures how acidic or alkaline a substance is, with 7 being neutral. Hair and skin sit slightly acidic, around 4.5 to 5.5.

A shampoo formulated at a pH close to that of hair and scalp, usually between 4.5 and 5.5, so it cleans gently without swelling the cuticle or stripping colour.

A mixture with a pH above 7 that opens the hair cuticle and softens the fibre. Many colour, perm and straightening products rely on this action to penetrate the hair shaft.

The tough outer layer of overlapping scales that protects the hair shaft. When it lies flat, hair looks shiny and feels smooth; when it is raised or damaged, hair looks dull and loses moisture.

The thick middle layer of the hair shaft, made of long protein chains. It gives hair its strength, elasticity and natural colour, and it is where colour and perm chemicals do their work.

The innermost core of the hair shaft, a soft central channel that may be partly or completely absent, especially in fine hair. It plays little role in chemical services.

A strong chemical link between two sulfur-containing amino acids in the cortex. These bonds hold hair in its shape and must be broken to reshape hair, then rebuilt to lock the new form in place.

The active chemical in a perm or straightener, usually a thioglycolate or hydroxide, that breaks disulfide bonds so hair can be wound or smoothed into a new shape.

The second-stage solution applied after processing a perm or straightener. It rebuilds the disulfide bonds in their new position, fixing the shape so it holds through later shampoos.

A strong alkaline product, often based on sodium hydroxide or guanidine hydroxide, that straightens tightly curled hair by breaking and then reforming its bonds. It requires careful scalp protection and timing.

A protective ointment applied along the hairline, ears and nape before a relaxer or other strong chemical service, to shield skin from irritation and chemical burns.

A small amount of a product applied to the skin, usually behind the ear or on the inner forearm, 24 to 48 hours before a colour or chemical service to check for an allergic reaction.

A trial application of a colour, bleach or perm product on a small hidden section of hair to predict timing, result and possible damage before treating the whole head.

A general term for checking how a client's skin responds to a product before a service. It may involve a patch test or a small dab on the scalp, and results are recorded in the client's file.

A condition or circumstance that makes a treatment unwise or unsafe, such as broken scalp skin, a recent allergic reaction or a client who should not receive chemicals at all.

Inflammation of the skin causing redness, itching, swelling or flaking. On the scalp or hands it may be irritant or allergic, and it can be a reason to postpone or avoid chemical services.

An immune reaction to a substance that is harmless to most people. In the salon it can show as itching, redness, swelling or breathing difficulty, and it must be taken seriously.

The spread of germs from one person, tool or surface to another. Salons prevent it through hand washing, tool disinfection and single-use items.

Using a chemical agent to reduce harmful microorganisms on tools and surfaces to a safe level. It is the standard level of protection for most salon equipment after each client.

A process that destroys all microorganisms, including spores, on an item. It is stronger than disinfection and is used where the highest level of hygiene is required.

Material Safety Data Sheet: a document supplied with a chemical product that lists its hazards, safe handling, first-aid measures and storage requirements. Salons keep these accessible for every product used.

Control of Substances Hazardous to Health: a set of regulations requiring employers to assess, control and record risks from hazardous chemicals such as bleaches, colours and straighteners in the workplace.

A careful look at a task or product to identify what could cause harm, who might be harmed, and what steps will reduce that risk. It is recorded and reviewed regularly.

Anything with the potential to cause harm, such as a slippery floor, a hot tool or a corrosive chemical. A hazard becomes a risk when someone is exposed to it.

Designing the workspace, tools and working posture to fit the body. In hairdressing this means adjusting chair and basin height and avoiding long periods of stooping or stretching.

Pain or damage in muscles, tendons or nerves caused by repeated movements such as cutting or blow-drying. It is prevented by varying tasks, taking breaks and using correct technique.

The structured conversation before a service in which the stylist gathers information, examines hair and scalp, discusses options and agrees the plan and price with the client.

The visual and tactile examination of hair during consultation, noting texture, density, porosity, elasticity, condition and any previous chemical treatments that will affect the service.

How readily hair absorbs and holds moisture and chemicals. Low porosity resists penetration, while high porosity absorbs quickly but loses moisture and colour fast.

The ability of wet hair to stretch and return to its original length. Good elasticity indicates healthy, strong hair; poor elasticity warns that chemical services may cause breakage.

A written or digital record of each client's services, products, timings, formulas and test results. It supports consistency, safety and professional accountability.

The method of wetting, applying and massaging shampoo into the scalp with the fingertips, then rinsing thoroughly. Correct technique cleans without tangling or irritating the scalp.

Gentle, rhythmic pressure on the scalp using the fingertips or palms to stimulate circulation, relax the client and loosen debris before or during shampooing.

The natural oil produced by glands in the scalp that lubricates hair and skin. Too much makes hair greasy; too little leaves hair dry and the scalp flaky.

Flaking of dead skin from the scalp, often with itching. Mild cases respond to medicated shampoo, but persistent or inflamed scalps should be referred to a doctor.

A product applied after shampooing to smooth the cuticle, restore moisture and make hair easier to comb. It is rinsed out or left in, depending on its formulation.

A conditioning service that adds protein to damaged hair to temporarily strengthen the cortex and improve elasticity. It is often used after lightening or repeated chemical work.

A hydrogen peroxide solution that, when mixed with colour or bleach, opens the cuticle and triggers the colour change. Its strength is measured in volumes or percentages.

The chemical reaction in which developer releases oxygen, lifting natural pigment or developing an artificial colour inside the hair. It cannot be reversed once it has occurred.

A lightening product that removes natural or artificial pigment from the hair, leaving a lighter base. It is strong and requires careful timing, strand testing and condition monitoring.

The period a chemical product is left on the hair to complete its reaction. It is set by the manufacturer and adjusted for hair condition, and it must never be guessed.

A cutting technique in which the scissor tips cut into the ends of a section to soften the line and create texture. It is used on dry or wet hair depending on the desired finish.

Dividing the hair into clean, controlled partings before cutting, colouring or styling so each area is worked evenly and the result is balanced and predictable.

Cutting straight across a section with the scissors parallel to the ends, producing a solid, heavy line and maximum weight at the perimeter.

The standards of behaviour expected of a stylist, including punctuality, confidentiality, honesty, respect for clients and colleagues, and working within one's competence.