cura dei capelli decifrata
Immergiti nel mondo della cura dei capelli con 'Haircare Decoded'. Sappiamo che orientarsi tra la vasta gamma di prodotti e trattamenti per capelli può essere opprimente. Ecco perché ci impegniamo a offrirti soluzioni efficaci e accessibili per ogni esigenza dei capelli. Con formulazioni pulite e altamente efficienti, la gamma JUST affronta le comuni preoccupazioni per i capelli. Da ingredienti rinforzanti a trattamenti rivitalizzanti, abbiamo tutto ciò di cui hai bisogno! Ma come determinare il tuo tipo di capelli? Quali prodotti si adatteranno meglio alle tue esigenze e forniranno i risultati desiderati? Tutto inizia con Hair Biology, e ti invitiamo a intraprendere questo viaggio per decifrare tutti i suoi segreti.
Struttura dei capelli
I capelli sono presenti su quasi tutte le superfici della pelle umana. È un filo di cheratina sottile con grande resistenza ed elasticità. Ogni capello è composto da una radice incorporata nel derma e da un fusto che sporge dalla superficie della pelle. La radice è circondata da una guaina tubolare di cellule epiteliali chiamata follicolo pilifero. La base della radice e del follicolo pilifero è leggermente più grande rispetto al resto della radice; questa struttura a forma di cipolla è chiamata bulbo pilifero.
Il bulbo pilifero riceve ossigeno e nutrienti tramite i vasi sanguigni che forniscono le cellule in crescita attiva nel follicolo pilifero intorno al bulbo pilifero, noto come matrice del capello.
Queste cellule sono l'unica fonte di nuovi capelli. Il fusto del capello stesso deriva dalla regione bulbosa della radice ed è prodotto da cheratinociti della matrice che si moltiplicano rapidamente. Il fusto è composto interamente da cellule morte costituite principalmente da cheratina. Queste cellule rimangono attaccate tra loro da una sostanza simile a cemento intercellulare.
Anatomia dei capelli
Se fai un taglio trasversale di un fusto di capello, troverai tre componenti principali, dall'esterno all'interno: la cuticola, la corteccia e la midolla.
Cuticola
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.
La corteccia si trova sotto la cuticola e contribuisce alle proprietà meccaniche della fibra capillare, inclusi forza, elasticità e ricciolatura. La corteccia è composta da cellule allungate ricche di filamenti di cheratina e da una matrice amorfa di proteine solforose.
È la presenza di melanina nella corteccia a dare colore ai capelli. Con l'invecchiamento, la quantità di pigmento prodotto diminuisce e questa è la ragione per cui i capelli diventano grigi. Inoltre, i cambiamenti legati alla colorazione ossidativa dei capelli, alle onde permanenti e alla stiratura, e allo styling termico avvengono tutti nella corteccia. La corteccia, simile alla cuticola, ha una grande importanza cosmetica, poiché le sue proprietà ottiche influenzano fortemente il colore e la lucentezza della fibra capillare.
La midolla (il “nucleo”) è composta da cellule appiattite e cheratinizzate. È vista come una struttura di cheratina.
Ciclo di crescita dei capelli e perdita dei capelli
La crescita dei capelli è un processo unico e complesso che coinvolge cicli continui di crescita e rigenerazione (fase anagen), transizione (fase catagen) e riposo (fase telogen). L'attività ciclica continua per tutta la vita, ma le fasi del ciclo cambiano con l'età.
Fase Anagen
Durante la fase anagen, nuovi capelli vengono prodotti nella parte inferiore del follicolo pilifero. Normalmente, la maggior parte dei capelli del cuoio capelluto (circa l'85-90%) si trova nella fase anagen in qualsiasi momento. Sul cuoio capelluto, la fase anagen può durare da 2 a 6 anni, ma in alcuni casi può essere più lunga. Più lunga è la fase anagen, più a lungo i capelli possono crescere. La differenza nella lunghezza dei capelli degli individui può essere correlata alla diversa lunghezza della fase anagen. I capelli del cuoio capelluto crescono a un ritmo normale di circa 1 mm ogni 3 giorni. I capelli su braccia, gambe, ciglia e sopracciglia hanno una fase anagen molto più corta e un tasso di crescita più lento, il che spiega perché sono molto più corti rispetto ai capelli del cuoio capelluto.
Fase Catagene
La fase catagen è una breve fase di transizione tra la fase di crescita e la fase di riposo, che segna la fine della fase di crescita. Sulla cuoio capelluto, la fase catagen di solito dura tra le 2 e le 3 settimane.3 Durante questa fase, la divisione cellulare si ferma, il tubo follicolare si restringe e si stacca dalla papilla dermica, e la base del follicolo si sposta verso l'alto, verso la superficie della pelle. La produzione di melanina si ferma in questa fase, portando a un'estremità inferiore non pigmentata nei capelli.
Fase telogenica
La fase telogenica è l'ultima fase e dura fino a quando i capelli completamente cresciuti non cadono.\n\nI capelli cadono durante la fase telogenica o rimangono al loro posto fino alla successiva fase anagen, quando i nuovi capelli che crescono\n\nli spingono fuori. Sul cuoio capelluto, la fase telogenica di solito dura circa\n\n2–3 mesi. Non appena la fase telogenica termina, i capelli tornano alla prima\n\nfase e l'intero ciclo ricomincia. Nuovi capelli appaiono dallo stesso follicolo.\n\nLa rimozione dei capelli telogenici è facile e indolore, questi sono i follicoli piliferi che\n\nescono durante lo shampoo o la pettinatura dei capelli.
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)
Fatto interessante
I capelli diventano più caricati negativamente dopo la spazzolatura. Queste cariche negative si respingono a vicenda e rendono i capelli crespi.
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.
Prodotti non ossidanti
I prodotti che appartengono a questa categoria non contengono agenti ossidanti, come suggerisce il nome. Di conseguenza, i coloranti non ossidanti non possono produrre tonalità più chiare rispetto alla tonalità originariamente presente e non possono scurire significativamente il colore originariamente presente.
Coloranti temporanei
I coloranti temporanei o i risciacqui colorati contengono solitamente molecole troppo grandi per penetrare nel corticale del capello e hanno anche bassa affinità per i capelli, il che significa che le forze di legame tra la cuticola del capello e le molecole del colorante sono basse. Di conseguenza, i coloranti temporanei forniscono un rivestimento debole sulla cuticola del capello e vengono facilmente rimossi dopo il primo shampoo. (risciacqui colorati, shampoo che esaltano il colore, spray per capelli, mousse, prodotti in gel)
Semi-permanente
I coloranti per capelli semi-permanenti di solito utilizzano coloranti abbastanza piccoli da penetrare nella cuticola dei capelli fino a un certo grado, oltre a macchiarli dall'esterno, e, quindi, rimangono sui capelli sani per 6–8 lavaggi con shampoo.
Il pH dei coloranti semi-permanenti è leggermente alcalino (7.0–9.0), facendo gonfiare e sollevare la corteccia. Ciò consente un certo grado di penetrazione del colorante negli strati più profondi della cuticola. Lavare i capelli apre la cuticola, consentendo al colore di svanire nel tempo a causa della solubilità dei coloranti in acqua. (lozioni, shampoo, gel, creme e mousse).
Prodotti ossidanti
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.