Chemical Terms Cosmetologists Should Know©

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Absorption - When a substance is entered inside the hair shaft it is known to be absorbed. 

Adsorption - When a substance is present only on the outer surface of the hair, it is known to be adsorbed. 

Acid - The word acid is derived from the Latin word acidus, meaning sour or tart and also related to the Latin word acetum meaning vinegar. Therefore, properties commonly associated with water solutions of acids are sour or tart in taste. Acids are rich in hydrogen ions or protons and they change the colour of litmus from blue to red. 

Acidic - the pH of acid solutions ranging from 0.1 to 6.9 and these acid solutions are called acidic in nature. 

Alkali - A water soluble substance capable of liberating hydroxide ions (OH) in water. The pH of such a solution ranges from 7.1 to 14.0. The examples of alkaline solutions are sodium hydroxide, lithium hydroxide and potassium hydroxide bases which are also termed as 'lye'. Guanidine hydroxide is also alkaline in nature.

Acid-Balanced or pH Balanced - 

Having a pH of 4.0 to 6.0

Aquatic Balance - A state achieved when the hair is infused with and/or retains the level of moisture characteristics of normal human hair.

BiocomphHlex - A compound of organic materials, capable of attaching to the hair. Depending upon the chemical composition, the BiocompHlex can serve a number of purposes including reducing porosity, realigning the cuticle layer and deep conditioning within the hair shaft.

Cationic - Descriptive of positively- charged molecules, existing in water miscible conditioners, that adhere to negative and/or damaged sites on the hair shaft. Cationic conditioners, dependent upon the level and strategy of formulation, can impart sheen, body and a silky feel to the hair. 

Cationic Humectants - A combination of cationic compounds and humectant compounds that attach electronically to damaged areas along the hair shaft to properly balance moisture levels (also see humectants).

Chelating Agent - A material which ties up calcium, magnesium or metal ions so that they are no longer effective. Products with chelating agents have the ability to extract calcium and magnesium ions from the surface of the hair fiber, rendering hair more pliable.

Cortex - The middle or inner layer, which gives strength and elasticity to the hair, is made of fibrous substance formed by elongated cells. This layer contains the pigment that gives the hair its colour. 

Cuticle - The outside horny layer, is composed of transparent, overlapping, protective scale-like cells, pointing away from the scalp towards the hair ends. Chemicals raise these scales so that solutions can enter into the hair cortex. The cuticle protects the inner structure of the hair. 

Cysteine - An amino-acid easily oxidized to cystine; obtained by the reduction of cystine. 

Cysteine Bonds - When cystine bonds are reduced or broken in the middle by reducing agents like Ammonium Thioglycolate. 

Cystine - A sulphur containing amino-acid found in hair and nails.

Cystine Cross- Links - Disufide bonds within the hair that connect or cross-link two polypeptide chains (much like the rungs of a ladder). 

Diameter of Hair - (Coarse, medium or fine) - Coarse hair has the greatest diameter. Fine hair has the smallest.

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Elasticity - The ability of the hair to stretch and return to its original length without breaking. Normal hair has its limitations as to the amount of pull or pressure it can withstand. Under normal conditions, the hair can be safely stretched about one-fifth of its length. Hair that has normal elasticity presents a healthy and lustrous appearance. A deficiency in the elasticity of hair causes it to become lifeless and limp. Very little elasticity is left in hair that has been abused by overprocessing during chemical services.

Elipticity - The cross-sectional shape of hair. Hair assumes the shape, size and direction of the follicle. It is a ratio of major and minor axis in the cross-section of hair. African hair has elipticity of 1.80 whereas Caucasian and oriental hair have elipticity of 1.4 and 1.1 respectively. 

Fibrilliar Network - A conditioning reparative firm that encases each hair strand to improve the hair's overall condition.

Fixative - A chemical agent capable of stopping the processing of a chemical hair relaxer and transforming the hair to its new form such as a neutralizer or stabilizer. 

Follicle - The tube-like depression or pocket in the scalp containing the hair root. 

Fragilitas crinium - Technical term for brittleness of the hair. 

Guanidine Hydroxide - An organic base which is used as a hair straightening agent with a relatively low potential for scalp irritation.

Hair Bulb - A thickened, club shaped structure forming the lower part of the hair root. The lower part of the bulb is hollowed out to fit over and cover the hair papilla.

Hair Papilla - A small cone-shaped elevation located at the bottom of the hair follicle which fits into the hair bulb. It is through the papilla that nourishment reaches the hair bulb. The papilla has the ability to produce hair cells. As long as the papilla functions, the hair will grow. 

Hair Root - That part of the hair contained within the hair follicle beneath the skin's surface. 

Hair Shaft  - That portion of the hair which projects beyond the skin. 

Hair Test - A sampling of how the hair will react to a particular treatment.

Humectants - Chemical substances capable of attracting moisture from the atmosphere onto the hair shaft (i.e., glycerin, propylene glycol). Especially beneficial for moisturizing dry, brittle hair and retaining proper moisture balance. 

Hydrator - A substance capable of adding moisture to the hair. 

Hydration - The act of adding water to a substance or material. Relative to hair care, hydration refers to adding moisture with humectants and other conditioning agents, to correct or prevent dryness.

Hydrogen Bonds or H-Bonds - The cross-bonds or links that are more numerous than sulfur bonds, but they are much weaker and can be broken easily with water or chemicals. 

Hydrolyzed - The breaking down of a substance into smaller components. A large polypeptide chain of protein, for example, can be hydrolyzed into smaller polypeptide chains so that it can pass through the cuticle, penetrate into the cortex, and replace the keratin that has been lost from the hair. 

Hygroscopic - The ability to attract moisture from the atmosphere. 

Inter-Fiber Friction - The resistance experienced among hair strands during combing and brushing; particularly acute when hair is damaged or lacking in proper conditioning. 

Imbrications - Cells arranged in layers overlapping one another; found in cuticle layer of hair. 

Internal Molecular Flow - A phenomenon that occurs during the permanent waving process (before oxidation) whereby the molecules of the hair have adjusted to their new curly/wavy configuration. The significance of this process is that when complete, the curl and wave patterns are strengthened. 

Keratin - The hard protein of which hair is composed. 

Lanthionization - The process whereby hair is permanently relaxed or straightened. It involves changing one third of the hair's cystine bonds (which consists of two sulfur atoms) to lanthionine bonds (consisting of one sulfer atom). Sodium hydroxide and guanide hydroxide are two commonly used active ingredients that effectively lanthonize excessively curly hair.

Macrofibrous - Descriptive of certain conditioning materials that are in the form of relatively large thread-like particles, similar in structure to the cortex of the hair. They effectively fill in larger cavities and damaged sites on the hair shaft, to leave hair smooth, soft, shiny, silky feeling and very easy to comb. (These macrofibrous conditioning agents are present in Affirm in 1 Reconstructer). 

Medulla - The innermost layer, is referred to as the pith, or marrow of the hair shaft and is composed of round cells. The medulla may be absent in fine and very fine hair. 

Melanin - The dark or black pigment in the epidermis and hair. 

Microfibruous - Descriptive of certain conditioning materials that are in the form of very small spider-web like particles. They act as fillers in the tiny crevices and damaged sites on the hair shaft, to even out porosity, smooth cuticles and strengthen hair temporarily. 

No-Base Relaxers - Creme relaxers that contain adequate amounts of petrolatum and/or mineral oils to help protect the scalp against the irritating effects of sodium hydroxide or guanidine hydroxide. The need to manually apply oils to the scalp is virtually eliminated. 

Normal Hair Shedding - The average daily hair shedding is estimated at 50-80 hairs. Hair loss beyond this estimated average indicates some scalp or hair troubling. 

Overlapping - Condition caused by a relaxer touch up when the cream overlaps onto previously treated hair. The result of overlapping during a relaxer application is usually severe hair damage or breakage. 

Oxidizing Lotion - A solution used in the permanent waving process which is rich in oxygen-containing compounds (i.e. sodium bromate and hydrogen peroxide). It works to reform the reduced cystine (cysteine) bonds and lock-in the new curl or wave pattern.

Peptide - A compound of two or more amino-acids containing one or more peptide groups; continuous filaments in the case of fiber protein or keratin. 

Permanent Hair Color - Hair colour formulated to penetrate the cuticle and deposit molecules of pigment into the cortex. Permanent hair color usually contains an aniline tint, which is a coaltar derivative. These penetrating tints can lift and deposit color in one step.

pH (Potential Hydrogen) - A measurement ranging from 0 to 14.0 that measures the relative degree of acidity or alkalinity of a substance. Healthy hair and scalp are slightly acidic, at a pH of 4.5-5.5 and are only balanced within this range. At a high (alkaline) pH, the hair shaft swells and cuticles are opened. At a low (acidic) pH, the hair shaft contracts and cuticles are closed very tightly, inhibiting the absorption of conditioners. 

Pilus - Plural for "pili," meaning hair. 

Polypeptide - Strings of amino acids joined together by peptide bonds, the prefix "poly" meaning many. 

Polypeptide Chains - A complex internal structure within hair, characterized by linkages of various amino acids. 

Positively-Charged Compounds - Descriptive of a very large number of different agents that attach electronically to the negative sites of the hair shaft. (The normal hair strand has a balance of both positive and negative charges. Should the hair become damaged, the number of negative sites increases). Depending upon the specific compound of grouping of compounds, the effect will be to reduce combing friction, realign the hair shaft, make hair more pliable, improve the optical qualities of hair (i.e. shine and fullness), eliminate static electricity, lubricate the hair shaft, etc.

Protein - A complex organic substance present in all living tissues, such as skin, hair and nails; necessary in the daily diet; also present in skin and hair conditioners. 

Pull Test - A test to determine the degree of elasticity of the hair. 

Redox - The process whereby curls or waves are chemically and permanently formed into the hair. It involves two distinct chemical processes: reduction and oxidation. Reduction entails the cleavage of breakage cystine bonds via rearrangers. The altered bonds are called cysteine bonds or half cystine bonds. Oxidation is accomplished when oxidizing solution (formulated with sodium bromate or hydrogen peroxide) is applied to rodded hair. As the hair is neutralized, the majority (80-85%) of cysteine bonds are reformed back to cystine bonds. The new curl pattern is then locked into the hair permanently. 

Relaxer - A chemical applied to the hair to straighten excessively curly hair. 

Relaxer Testing - Checking the action of the relaxer in order to determine the speed at which the natural curl is being removed. 

Semi Permanent Hair Color - Hair color formulated to last from 4-6 shampoos. It penetrates the hair shaft slightly, depending on the porosity of the hair. Uses no peroxide for development.

Strain - The degree or percentage of stretching of a hair fiber under certain degrees of stress or force.

Stress - The pull or force put on the hair during combing, brushing, styling or simply stretching while determining elasticity of hair. 

Sulfur Bonds or S-Bonds - The cross bonds or links that are very strong and can only be broken by a strong chemical. 

Temporary Hair Colour - Hair color which coats the cuticle and is formulated to last only from shampoo to shampoo.

Tensile Strength - The amount of pull or pressure that can be induced on a single hair fiber without breakage. 

Texture - The general quality of hair, as to coarse, medium or fine; the feel to the hair. 

Thio  (Ammonium Thioglycolate) - chemical hair relaxer. 

Touch-up - The application of relaxer to the new growth of the hair, being extremely careful not to overlap onto previously treated hair.

Trichoptilosis - A splitting of the hair ends, giving them a feathery appearance. 

Trichorrhexis Nodosa - Disease of the hair shaft initially characterized by nod-like structures eventually leading to shredding and weakened areas along and within the hair shaft, leaving the cortex fibers exposed and fraying. As the hair is combed and styled, the implements snag the damaged sites, causing more extensive damage and eventual breakage. Common causes are mechanical, thermal, chemical and/or environmental (i.e sun) damage.

Upper Mantle - The outermost surface of the hair shaft (cuticle). 

Virgin Hair - That that has had no chemical services or damage from natural factors such as wind, sun, etc.