haircare decoded
Dive into the world of hair care with 'Haircare Decoded'. We know navigating the vast array of hair products and treatments can be overwhelming. That's why we're committed to bringing you effective, accessible solutions for every hair need. With clean, highly efficient formulations, the JUST range addresses common hair concerns. From strengthening ingredients to revitalizing treatments, we've got you covered! But how to determine your hair type? Which products will best suit your hair needs and deliver the results you desire? It all starts with Hair Biology, and we invite you to embark on this journey to decode all its secrets.
Hair Structure
Hair is present on almost all surfaces of the human skin. It is a thin keratin thread with great strength and elasticity. Each hair consists of a root embedded in the dermis and a hair shaft sticking out the surface of the skin. The root is surrounded by a tube-like coat made of epithelial cells called the hair follicle. The base of the root and hair follicle are slightly larger than the rest of the root; this onion-shaped structure is called the hair bulb.
The hair bulb receives oxygen and nutrients via the blood vessels which supply the actively growing cells in the hair follicle around the hair bulb known as the hair matrix.
These cells are the only source of new hair. The hair shaft itself arises from the bulb region of the root and is produced by rapidly multiplying matrix keratinocytes. The shaft is made up entirely of dead cells composed mainly of keratin. These cells remain attached to each other by an intercellular cement-like substance.
Hair Anatomy
If you do a cross-section of a hair shaft you will find three major components, from the outside to the inside: the cuticle, cortex, and medulla.
Cuticle
Cortex
Medulla
The outermost structure is the cuticle. It is composed of multiple layers of keratinized, flattened cells, which overlap in a roof-tile. It is translucent, allowing light to penetrate the cortex pigments. It is composed primarily of keratin. The cuticle regulates the water content of the hair fiber, and is responsible for the luster and the texture of hair. The cuticle is the target for hair conditioning products. Shiny and soft hair reflects a healthy cuticle, while dry, brittle hair is the result of damaged cuticle cells.
The cortex lies below the cuticle and contributes to the mechanical properties of the hair fiber, including strength, elasticity, and curliness. The cortex consists of elongated cells rich in keratin filaments as well as an amorphous matrix of sulfur proteins.
It is the presence of melanin in the cortex that gives hair color. During aging, the amount of pigment produced is less and this is the reason for graying of the hair. In addition, the changes involved in oxidative hair coloring, permanent waving and straightening, and thermal styling all take place in the cortex. The cortex, similar to the cuticle, has a great cosmetic importance, as its optical properties strongly affect the color and shine of the hair fiber.
The medulla (the “core”) is composed of flattened, cornified cells. It is viewed as a framework of keratin.
Hair growth cycle and Hair Loss
Hair growth is a unique and complex process that involves continuous cycles of growth and regeneration (anagen phase), transition (catagen phase), and resting (telogen phase). The cyclic activity continues throughout life, but the phases of the cycle change with age.
Anagen Phase
During the anagen phase, new hair is produced in the lower part of the hair follicle. Normally, most of the scalp hair (approximately 85–90%) are in their anagen phase at any time. On the scalp, the anagen phase can last 2–6 years, but in some cases, it may be longer. The longer the anagen phase, the longer the hair is able to grow. The difference in individual’s hair length can be related to the varying length of the anagen phase. Scalp hair grows at a normal rate of about 1 mm every 3 days.The hair on the arms, legs, eyelashes, and eyebrows have a much shorter anagen phase and a slower growth rate, explaining why it is much shorter than the scalp hair.
Catagen Phase
The catagen phase is a brief transition phase between the growth and the resting phases, which marks the end of the growth phase. On the scalp, the catagen
phase usually lasts between 2 and 3 weeks.3 During this phase, cell division
stops, the follicle tube shrinks and detaches from the dermal papilla, and the
base of the follicle moves upward toward the surface of the skin. Melanin production stops in this phase, leading to a non-pigmented lower end in the hair.
Telogen Phase
The telogen phase is the final phase and lasts until the fully grown hair is shed.
The hair either shed during the telogen phase or remains in place until the next anagen phase, when the new hair growing in
pushes it out. On the scalp, the telogen phase usually lasts for approximately
2–3 months. As soon as the telogen phase ends, the hair returns to the first
phase and the entire cycle begins again. New hair appears from the same follicle.
Removal of telogen hairs is easy and painless, these are the hair follicles that
come out during shampooing or combing the hair.
How you know whether you are losing the telogen or anagen hair?
The shape and color of the bulb are different for telogen and anagen hairs. Telogen bulbs are club shaped, and unlike anagen hair, their base is devoid of pigment. It can be clearly seen with a magnifying glass.
Other factors influencing hair growth are systemic factors, such as hormones, including androgens, estrogens, and thyroid hormones; growth factors and cytokines; as well as external factors linked to the environment, such as toxins, and deficiencies of nutrients, vitamins, and energy.
Chemical composition of hair
Hair fibers are primarily composed of various types of keratin. The keratin fibers consist of long molecular chains intertwined and firmly attached through various bonds. Bonds found in hair fibers are generally classified as strong bonds and weak bonds.
Strong bonds
Disulfide Bonds:
Hair keratin is made up of amino acids, where cysteine is one of the most important among them. Cysteine molecules with their sulfur atoms are able to form a very strong bond known as the disulfide bond. They contribute much to the shape, stability, and texture of the hair. When two cysteine molecules are bound together through a disulfide bond, a molecule called cystine is formed. Disulfide bonds are called strong bonds, because they cannot be broken up by heat or water, only chemically. These bonds remain intact when the hair is wet, allowing the hair to resume its original shape.
Weak bonds
Hydrogen Bonds (H-bonds):
H-bonds are relatively weak and can be easily broken by water and heat. They are primarily responsible for changing the hair’s overall shape. Although individual H-bonds are weak, they are present in the highest number of all types of bonds; therefore, they significantly contribute to the strength of hair fibers.
Salt Bonds:
Also known as ionic bonds, are sensitive to pH; therefore, they are easily broken by strong alkaline or acidic solutions. Although these are weak bonds, together they account for a significant part of the strength of hair fibers.
Van der Waals Forces:
These forces are weak attractive forces between neutral molecules in close contact. They can also be easily broken by water and heat.
Hair types
Based on Color
Natural color is the result of melanin present in the cortex. There are two types of melanin: eumelanin, which provides dark brown and black color to hair, and pheomelanin, which provides red to blond tones.
Naturalhair color ranges from black, brown, and blond to red with subtle hues in each category. The diversity of hair pigmentation results mostly from the quantity and ratio of eumelanin and pheomelanin.
Based on Condition
The hair’s condition refers to the smoothness and softness of the hair by touch, which is in direct relationship with the cuticle’s intactness. This is commonly called porosity, which reflects the hair fibers’ ability to absorb moisture.
- Healthy hair with a compact cuticle layer is naturally resistant to moisture.
- If the cuticle is damaged, hair has a course texture and loses its shine and smoothness. In such cases, the cuticle is raised, meaning that the layers are not tightly packed. This type of hair is referred to as porous or overporous hair if damaged severely. Porous hair can absorb liquids very easily and quickly and tends to develop split ends.
The hair fibers’ condition should be considered before undergoing chemical processes, such as hair coloring since the needs of damaged and healthy hair are different.
Based on Curliness
Refers to the shape of the hair shaft. There are a variety of categories describing the curliness of hair, including straight, wavy, curly, and kinky, among others. The conventional classification of curliness distinguishes three types of hair: African, Caucasian, and Asian. Usually, Asian hair is the thickest, followed by African hair, and then Caucasian hair. An additional feature is the cross-sectional shape of the hair fibers: Caucasian and Asian hairs typically has a similar round shape, with the Asian hair being more cylindrical, while the African hair has a highly elliptical shape.
Today, we can find hair types that would not fit into these three basic categories. Therefore, there are newer classifications developed that categorize hair into more than three groups, regardless of its ethnical origin.
Based on Greasiness
Based on greasiness, two major hair types are usually differentiated- dry and greasy hair.
Dry hair does not contain enough moisture. It is usually a result of damaged cuticle and cortex. Porous cortex cannot retain water; therefore, hair fibers have dull, unhealthy appearance.
Dryness is usually aggravated by excessive shampooing and chemical treatments, such as permanent waving or bleaching. Extremely dry hair needs special care and mild cleansing agents not to worsen the damage.
Greasy hair is usually caused by overactive sebaceous glands, which produce more sebum than normally. Since sebum production is highly influenced by hormones, many consumers experience greasy hair when changes take place in their hormone levels, for example, during puberty. In such cases, the hair may become greasier and need to be washed more often. Greasy hair needs special care because if not cleaned adequately, it can lead to various scalp conditions, such as dandruff.
Hair cleansing
Shampoos are one of the most widely and frequently used personal care products today.
The main benefit of using shampoos is the removal of dirt on the hair. Similarly to dirt on the skin, dirt on the hair consists of sweat, sebum and its breakdown products, dead skin cells, residues of cosmetics and personal care products, dust, and other environmental impurities carried in the air.
Most of these compounds are not soluble in water; therefore, washing the hair with simple water would not be sufficient to remove dirt. Shampoos contain surfactants (similar to skin cleansers), which are able to remove oily particles from the hair.
From the aspect of their chemical nature, shampoos are surfactant-based preparations. Therefore, their cleaning principle is emulsification. Surfactants surround and trap tiny droplets of fat, which in this form can be rinsed off from the hair and scalp. Insoluble particulate soil can be removed by electrostatic repulsion between the soil and the hair fiber assisted by repulsion between the surfactant molecules adsorbed onto the hair fiber and those dissolved in the soil.
Today shampoos are available as liquids, gels, emulsions and powders. Most commonly, shampoos are colloidal dispersions of various surfactants in water. Basic components of a classical shampoo are cleansing agents, thickeners, and water. Usually, various additives are also incorporated in the formulations in order to help the cleansing process, enhance the aesthetic properties, increase foaming, and make the hair shine.
What is the role of surfactants and are they different?
Surfactants aid in cleaning and foaming by reducing the surface tension between two phases. In addition, surfactants can also act as foam boosters and foam stabilizers. Typically, several surfactants are combined to achieve the desired result. For example, shampoos for oily hair contain surfactants with strong sebum removal qualities, unlike those for colored hair that are gentler to the hair. Different surfactants, however, have different characteristics and effects on the hair and scalp. Anionics can make the hair extremely clean, but will leave it with a rough, harsh feeling; while nonionics can increase luster and shine, but they do not foam as well as anionics.
Hair conditioning
Conditioners are applied to the hair after shampooing and are designed to smooth the hair, improve gloss and luster, as well as recondition chemically damaged hair (by permanent waving, hair bleaching, or hot blow-drying), mechanically damaged hair (by excessive brushing), and weathered hair (by sunlight, salty seawater, chlorinated water, or swimming pools).
Conditioners act by reducing static electricity generated after combing dry hair, improving manageability by filling in the gaps around and between the cuticle scales, increasing hair shine by coating hair shafts with a thin layer,decreasing split ends, and improving hair flexibility. Natural sebum is the ideal conditioner. Excessive removal of sebum leads to a harsh and dull appearance of the hair, and it necessitates the use of synthetic sebum-like products.
Conditioners make the hair soft, shiny, and easier to manage. Although the main purpose of using shampoos is to clean the hair, overcleaned hair looks dull and has less shine. Conditioners can be incorporated into shampoos; products containing such ingredients are usually referred to as two-in-one shampoo and conditioner formulations. Conditioners are particularly important in dry hair shampoos and shampoos for colored and bleached hair.
Examples for commonly used ingredients include quats (a type of cationic surfactant); humectants, such as glycerin; proteins; silicones, such as dimethicone)
Interesting Fact
Hair becomes more negatively charged after brushing. These negative charges repel each other and make the hair look frizzy.
Hair is one of the most important features when it comes to first impression and is strongly connected to attractiveness and confidence. Styled, well-kept hair gives the external appearance of being well managed, which in turn can contribute to feeling the same way internally. The key motivator for coloring the hair is graying. Graying can have a significant effect on both men and women, including emotional and psychological stress as well as lowered self-esteem.
Additionally, people are rarely satisfied with their natural hair color. A wide variety of hair coloring products offers an option to everyone to alter their hair color, which can also contribute to self-esteem and confidence.
Nowadays there are different types of hair-coloring products based on the presence or absence of the chemical reaction (known as oxidation) involved in the hair coloring process. Non-oxidative products include temporary dyes and semi-permanent dyes, while demi-permanent dyes, permanent dyes, and hair bleaches fall into the category of oxidative products.
Non-Oxidizing Products
The products that belong to this category do not contain oxidizing agents, as their name implies. As a result, non-oxidizing dyes are not able to produce lighter shades than the originally presenting shade and cannot significantly darken the originally presenting color.
Temporary Dyes
Temporary dyes or color rinses usually contain molecules that are too large to penetrate the hair cortex and also have low affinity to hair, meaning that the binding forces between the hair cuticle and the dye molecules are low. As a result, temporary dyes provide a weak coating on the hair cuticle and are easily washed out after the first shampooing. (color rinses, color-enhancing shampoos, hair color sprays, mousses, gel products)
Semi-Permanent
Dyes Semi-permanent hair dyes usually employ dyes that are small enough to penetrate the hair cuticle to some degree, in addition to staining it from the outside, and, hence, remain on the healthy hair through 6–8 shampooing.
The pH of semi-permanent dyes is slightly alkaline (7.0–9.0), making the cortex to swell and rise. It allows a certain degree of penetration of the dye into the deeper layers of the cuticle. Washing the hair opens the cuticle, allowing the color to escape over time because of the solubility of the dyes in water. (lotions, shampoos, gels, creams, and mousses).
Oxidizing Products
Oxidizing hair dyes are two-component systems: one component contains colorless dye and couplers in a highly alkaline formulation. The other component contains hydrogen peroxide (the oxidizing agent, otherwise known as the developer or activator). These products are mixed right before application, which generates a chemical reaction. The alkaline agent swells the hair cuticle and thus helps the penetration of the relatively small dye intermediates into the cortex. In addition, it also destabilizes hydrogen peroxide to liberate oxygen. The oxygen released destroys the hair’s natural melanin (i.e., lightens hair) and also oxidizes the dye intermediates and allows them to react with the couplers within the hair shaft to form a colored molecule. The final color molecule is too large to be removed by shampooing, which makes the color resistant to shampooing. (permanent, demi-permanent dyes, bleachers).
Interesting Fact!
Red shades tend to fade fastest as they have a relatively small molecule size, which can diffuse from the hair and wash away more quickly than other shades.