Hair Science: May 2008 Archives

Over the course of time, the internet has enabled end-consumers without formal cosmetology training to acquire a considerable amount of knowledge about haircare. Back in '94, I compiled a general list of terms for ShopTalk magazine that cosmetologists should know, but in reality, anyone interested in the proper maintenance of their hair should be familiar with these terms:

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 color 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 "Iye." 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 arc 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 a fibrous substance formed by elongated cells. This layer contains the pigment that gives the hair its color.

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 - Disulfide 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.

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 1.89 whereas caucasian and oriental hair have elipticity of 1.4 and 1.1 respectively.

Fibrillar Network - A conditioning reparative firm that encases each hair strand to improve the hairs overall condition.

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

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

Fragilitas criniurn - 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, clubshaped structure fanning 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-FiberFriction - 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 hairs cystine bonds (which consists of two sulfur atoms) to lanthionine bonds (consisting of one sulfur atom). Sodium hydroxide and guanide hydroxide are two commonly used active ingredients that effectively lanthionize 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™ 5 in 1 Reconstructor.)

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.

Microfibrous - Descriptive of certain conditioning materials that are in the form of very small spiderweb-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 trouble.

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 brom~ltc 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 color 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.

Porosity - Ability of the hair to absorb moisture due to lifted cuticle layers.

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 hair. It involves two distinct chemical processes: reduction and oxidation. Reduction entails the cleavage of breakage of 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 detennining 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 Color - 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 of 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 - Hair that has had no chemical services or damage from natural factors such as wind, sun, etc.

In 2000, I co-authored an article for C&T magazine regarding the scalp irritation potential of lye and no-lye relaxers. The article includes our findings from a study based on comfort/discomfort evaluations from salon patrons.

Compared to Caucasian hair, African-American hair is extremely curly and it's physical configuration resembles a twisted ribbon. It is highly unmanageable. very difficult to comb-both wet and dry-and hard to style. More fragile than Caucasian hair, this excessively curly hair breaks more easily when stretched or vigorously brushed and combed. Thus, African-American hair requires both special handling and hair-care products that are differently formulated than those for Caucasian hair.

Madam C. J. Walker: A Beauty Product Pioneer

Madam C. J. Walker was an early 20th century beauty product pioneer. She was born under the name Sarah Breedlove to ex-slaves in 1867. In her early life, she worked in both the cotton fields and the kitchen. In 1905, after marrying newspaper sales agent Charles Joseph Walker, she adopted his name and developed expertise in manufacturing hair goods and preparations.

Walker soon launched her own business, designing cosmetics and hair-care products for black women. From this business she became one of the nation's first female millionaires. Using her success for the good of others, she earned a reputation as a philanthropist to African-American institutions such as the NAACP, Tuskegee Institute and Bethune-Cookman College. She died in 1919.

In 1998, the US Postal Service issued a stamp commemorating her achievement as an African-American businesswoman and philanthropist. The image on the stamp is from a circa 1914 photo that was used extensively by Walker's company for publicity purposes, in advertising, and on its products.

The Development of Relaxers

In the early 1900s, an African-American domestic worker, later known as Madam C. J. Walker, invented pomade using a combination of oils (see sidebar). This pomade revolutionized the hairstyling practices of African-American women and made excessively curly hair softer, shinier and somewhat easier to comb. However, the pomade did not straighten the hair. African-American women still could not achieve styles like those worn by Caucasian women.

Here's a study that I helped author in 1995 regarding the physical properties of African American hair and how it differs from Caucasian hair. Enjoy.

Scientific innovations in chemical treatments that alter the texture of African-American hair, as well as a plethora of style trends, have spurred phenomenal growth in this
segment of the hair-care market throughout the past three decades. The level of research & development by manufacturers in the area of product formulation has steadily elevated; yet, a great deal remains to be learned about the unique physical properties of African American hair. Compared to the vast body of research regarding Caucasian hair, the study of African-American hair is at best limited.

A Review of Research

In published studies, J. Menkart et al, Epps et al and Kamath et al reveal that some important research has indeed been conducted on the physical properties of highly curly hair. The efforts of these researchers and the results of their studies serve as a starting point for the further study of African-American hair. Other general observations about hair, such as those pertaining to static charge (Jachowicz and C.R. Robbins) and theories about moisture content, serve as a springboard for advancing the study of African American hair.

Shape: Menkart and Wolfram report that African-American hair has a physical shape resembling a twisted oval rod, whereas Caucasian hair is more cylindrical. They found evidence of this when they made elliptic comparisons or hair cross-sections. Using a formula in which the minor axis is divided by the major axis, Menkart and Wolfram
determined that African-American hair has a ellipticity index of 0.56 and Caucasian hair has an index or 0.7.1. The tensile-strength data gathered during this research shows that the breaking stress of African·American hair (1.24 g/denier, a unit of fineness equal to the fineness of a yarn weighing 0.05g for each 450m of length or 19 for each 9000m.) is less than that of Caucasian hair (1.41 g/denier). The yield stress for African-American hair, however, is slightly higher (0.46 g/denier VS 0.42 g/denier).

Kamath and Hornby studied the fractographic behavior of African-American hair to view both major and minor rods at low levels of extension. They examined the ellipticity of
hair fibers and reported ellipticity indices of 1.89±0.083 and 1.0 to 1.4 for African-American and Caucasian hair, respectively. In this study, the ellipticity index was calculated by dividing the major axis by the minor axis, which is the reverse of the formula used by Menkart and Wolfram.

Combability: Epps and Wolfram conducted combing comparisons between African-American and Caucasian hair using combability techniques used by Garcia and Diaz. Garcia and Diaz report that African-American hair, due to its curliness, is much more difficult to comb than Caucasian hair. It was also determined that African-American hair is easier to comb wet than dry.

Using a scanning electron microscope at a magnification of about 300X, Kamath and Hornby also observed that African American hair display frequent twists with random reversals in direction and pronounced flattening. During fractographic study, the break stress of African-American hair was reported to be (0.123 ± 0.016) 10^9 N/m^2 when dry (65% relative humidity [RH]) and (0.119 ± 0.010) 10^9 N/m^2 when wet. The breaking elongation for wet and dry (65% RH) fibers was found to be 44% ±3% and 27% ± 5%, respectively.

Formulating superior products while maximizing shelf life is a difficult balance that each formulating chemist must achieve. Here's an article I wrote for ShopTalk magazine in 1993 regarding the shelf life and proper storage of salon products.

Shelf Life and Storage of Salon Products

Like many consumer products, certain salon products are best used during a particular increment of time. This interval of time is called shelf life, and it describes the period wherein a product can be used with maximum effectiveness and safety. Within this article, the average shelf life of various salon products will lie discussed. First, let's tum our attention to the primary determinants of shelf life.

Factors Which Affect Product Shelf Life

I. Product Development

A. Stability

The formulation of high-quality hair care products is both an art and a science. As experienced hair care chemists well realize, the way a product is formulated has a profound impact upon its shelf life. Expert chemists strive to develop products that meet or exceed the market standards in terms of performance, and always with the objective of achieving product stability. Stability refers to the maintenance of a products' basic character, an enduring uniformity of its blend and the preservation of a homogeneous state. An unstable formulation is many times evidenced by product "separation", whereby the ingredients become unblended. Both environment and gravity are key factors in stability. As a product ages, the environment (i.e. temperature, exposure to air, etc.) may cause the product to separate. Gravity also affects a product's life in that, over time, the weightiest ingredients (such as water) will segregate towards the bottom of a mixture, as others (like oils) are relegated to the upper pans.

B. Ingredient Selection

Certain ingredients are by their very nature more stable than others. For instance, animal proteins. particularly when used in high volume, are less stable than some other types of conditioning agents-because· of their proclivity for bacterial growth. And too, emulsifiers, used in formulas containing both oils and water, can be relatively ineffective in ensuring oil/water miscibility, (a uniform blending of these two components), over extended periods of time.

The Average Shelf Life of Salon Products

SHAMPOOS
Shelf Life: 1 to 2 years

Well formulated cleansing and lightly conditioning shampoos have relatively long shelf lives. Detangling shampoos, however, are more difficult to stabilize from a product development standpoint because of the amount of conditioning agents utilized. The shelf life of detangling shampoos may therefore be as limited as six months to a year.

CONDITIONERS
Shelf Life: 1 to 2 years

After-shampoo conditioners will last a year or two. If the formula contains an unusually high amount of organic material such as animal protein, the life of the product may well be much less due to an increased susceptibility to bacterial growth problems.

RELAXERS
Shelf Life: 1 to 1.5 years (Sodium Hydroxide)
2 years (Guanidine Hydroxide)

Of the most widely used relaxers, those formulated with sodium hydroxide are the most challenging to formulate. An improperly formulated relaxer can have a shelf life of six months or less. Well developed formulas will work effective for up to a year and a half.

 
Guanidine hydroxide relaxers are a little easier to stabilize from a product development standpoint, and can be effectively used for up to two years. (If the creme portion of the relaxer system seems a bit dry on the upper surface, do not assume that the product is beyond '" shelf life. This is characteristic of relaxers in this category, which contain
calcium hydroxide.)

PERMANENT WAVES
Shelf Life: 6 to 12 months Curl Boosters
6 to 12 months Rearrangers
1 year Neutralizers

The chemicals used to formulate permanent wave systems are very difficult to stabilize, primarily because the active ingredient, (ammonium thioglycolate), readily reacts with air. This is called "oxidation" and describes a process that neutralizes or deteriorates the active chemicals contained in curl boosters and rearrangers.

These two components of perm systems, which are critical to the straightening and curl formation of the hair, can easily lose up to 15% to 20% of potency due to ordinary exposure to the air. This potency loss significantly slows down the chemical reaction of the products.

Oxidation will occur to some extent with any exposure to air, even with the simple act of opening the container in which the booster or rearranger is packaged. More often, the process of oxidization is greatly accelerated by the bulk packaging typically used for professional perming products. By using large packaging, which is often demanded by stylists, the packaging is opened and closed on multiple occasions as clients are serviced. Also, more air is left inside the containers, called "head space", with each successive use of the products. (For this reason, the perms sold in the general market, (for curling naturally straight hair), are almost always packaged in single-use kits.) Due to the reactivity of ammonium thioglycolate to the air, compounded by the use of bulk packaging, the shelf life of curl boosters and rearrangers is generally six to 12 months.

Neutralizers, which do not contain the highly reactive ammonium thioglycolate, are effective for up to a year.

HAIRDRESSINGS
Shelf Life: 2 years 100% Oils
1 to 1.5 years Cremes

The 100% oils are the hairdressings commonly referred to as "greases" or "pomades." They have a relatively long shelf life. Cremes, however, (i.e. oil moisturizers and creme hairdressings), are oil and water emulsions and have a shelf life of up to one and one-half years. This is because over time, the oil will strive to the top of the emulsion, leaving the water at the bottom. Depending upon formulation, cremes may even have a shelf life as short as six months.

FINISHING PRODUCTS
Shelf Life: Up to 2 years

Most of the products in this classification have relatively extended shelf lives. Styling Gels maintain performance integrity from one to two years, depending upon the formula. Setting Lotions, Oil Sheen Sprays, Holding Hair Spray sand Laminates can last for two years or more.

HAIR COLORINGS
Shelf Life: 1 to 1.5 years

In a similar fashion to that described for permanent wave products, the active chemicals in many hair colorings are highly sensitive to the air. With oxidization, the ability of the color product to deposit within the hair shaft is impaired. To help prevent oxidization and the resultant potency loss, many such products are packaged in single-use bottles.

Proper Product Storage

Generally, salon products should be stored at room temperature, away from heat, direct sunlight and extreme cold. Storage of products in refrigerators is not recommended and products should never be placed in a freezer. To protect products from excessive sunlight and store products near windows.

Some Tell Tale Signs of Shelf Life Expiration

The following properties will signal that a product is beyond its shelf life:

- Product Separation
- Foul Odor (likely caused by bacterial contamination)
- Loss of Product Viscosity (product becomes much thinner)
- Build up of Viscosity (product becomes much thicker)
- Rancid Odor (characteristic of natural oils that have been exposed to air and/or sunlight for extended periods)

What if a Product is Used Past its Shelf Life?

At best, a product that is beyond its shelf life will not perform as effectively as it did initially. Product application may be impaired and the way it reacts to the hair may very well be hindered. At worst, the product could cause harm to a client. In the case of an unstable or separated sodium hydroxide relaxer, the result will either be ineffective straightening or extreme causticity. This is because once a relaxer separates, the oils rise to the top and the water, containing most of the sodium hydroxide, descends to the bottom of the jar. When the stylist applies the upper portion of the mixture, the hair will be treated with the most impotent part of the relaxer. When the lower portions in the jar are used, the relaxer is much too strong and will likely damage the hair and bum the scalp. Stylists must not think that merely mixing the contents of a separated relaxer will again stabilize the formula because it won't. Relaxers must be blended at a temperature of 80 C under scientifically-controlled conditions in order to get a stable mixture.

Another instance in which a client may actually be harmed by the use of product, which is beyond its shelf life, is when bacterial growth has occurred. Should a contaminated product, wherein the preservative system has broken down, be inadvertently rinsed.
into a client's eyes, severe infection and/or impairment may result.

How is a Professional Cosmetologist to Know?

Other than being on the lookout for the "tell-tale" signs listed above, there is really no good way for a cosmetologist to know precisely the age of a product and its shelf life as estimated by the manufacturer. Manufacturers normally code each product so that they will know precisely when it was manufactured. and via their scientific tests, manufacturers can also predict the shelf lives of their various products. (By law, companies must also retain samples of each batch of product; which they produce for three years, in order to track the impact of product aging within a controlled environment.) Should you have a specific question regarding the shelf life of a certain product, contacting the manufacturer may be the best avenue to pursue.

Dr. Ali Syed is president and master chemist of Avlon Industries. Melrose Park, IL