Although humans lost most of their hair during evolution, it remained an important means of brain protection, body heat retention, and individual expression. Hair is composed of the hair medulla, the hair cuticle, and the hair shaft, and dyeing involves the process of altering the melanin pigment in the hair shaft to achieve different colors. Permanent coloring is done by using ammonia and hydrogen peroxide to open the hair cuticle, remove the melanin, and infiltrate the dye.
The history of life that began in the oceans entered a new phase when it moved onto land. To survive in a different environment than in the water, life evolved, and in the process, skin gradually hardened and hair began to grow. Some creatures’ fur grew longer and thicker for warmth, while others were lighter and sleeker for gliding.
However, humans gradually began to shed their hair to quickly dissipate the heat from their enlarged brains, and most of it was lost, except in a few important areas. The hair that remained on the head came to have functions such as brain protection and body heat retention, as well as the ability to convey individual characteristics and messages. Especially in modern society, the meaning of hair has become more prominent, with women and examinees shaving their heads to show their will or determination, and punks’ auburn and pink hair showing their anti-establishment tendencies. They don’t hesitate to invest time and money in their hairstyles as a means of expression.
The importance of hair as a means of expression can be traced back to history. In ancient Egypt, royalty and aristocrats wore different wigs to signify their status, and in medieval Europe, hairstyles were used to express social status. Hair has become more than just a part of the body, it’s an important element of social and cultural identity. In the modern era, with the development of the fashion industry and a variety of hair styling methods, such as dyeing, perming, and cutting, it has become a primary means of expressing individuality and creativity.
But what are the properties of hair that make these activities possible, and what principles does hair coloring utilize? Let’s start by understanding the structure of hair.
Hair is composed of three main parts The innermost part is the medulla, the middle part is the cortex, and the outermost part is the cuticle. First, let’s talk about the medulla. The hair cortex is the center of the hair, and it’s made up of honeycomb-like polygonal cells filled with cavities, arranged lengthwise along the length of the hair. These cavities hold air, which helps to insulate the hair, and the more air they contain, the shinier it becomes. However, it’s not present in all hair, and depending on the thickness of the hair, it’s roughly present in hair over 0.09 millimeters, but almost invisible in hair under 0.07 millimeters.
Next is the hair cuticle. The hair cuticle is the outermost part of the hair, making up roughly 10-15% of the hair. It’s made up of a light protein called keratin and has a tile-like structure with 5 to 15 layers of transparent, thin cells. It is chemically resistant and protects the inner part of the hair, and when the cuticle is damaged, it is difficult to regenerate, affecting both the cuticle and the medulla, causing hair breakage.
Finally, let’s talk about the cortex. The cuticle is the part of the hair that lies between the medulla and the cuticle, and it makes up 85-90% of the hair. It doesn’t affect the color of the hair because it’s hollow and the cuticle is made up of transparent thin cells. However, the hair cortex is made up of cortical cells (keratin proteins) and intercellular connections, which contain a small amount of melanin pigment, which gives the hair its natural color. There are two main types of melanin pigments. One is eumelanin, which is mainly responsible for colors ranging from brown to black. The other is pheomelanin, which is red or yellow in color, and depending on the ratio of these two pigments, hair color can range from black to brown to gold. In addition to the color of the hair, it’s also a key part of the hair as it determines the overall characteristics of the hair, such as elasticity, strength, and texture.
To summarize, hair is made up of three parts: the hair shaft, the hair cortex, and the hair cuticle. The hair shaft and cuticle are responsible for anchoring the hair and protecting it from the elements, but they don’t play a major role in determining the color or other characteristics of the hair. It“s the components of the cuticle that make up the majority of the hair, and chemical treatments are used to destroy or modify these components. In this article, we”ll explain how hair coloring works.
There are three main types of hair coloring. One is temporary dyeing, which is the application of a dye to the outer layer of the hair cuticle to give it color. In this case, hair color sprays or color mousses are used to apply the color, but the effect disappears as soon as you wash it off. The other is semi-permanent dyeing, in which the dye is slightly absorbed into the cortex and forms a thin film on the surface of the epidermis. Hair coatings, nail polish, and waxing are common examples of this type of coloring. The advantage is that it doesn“t affect the cortex, so it doesn”t damage the hair. However, since it”s literally just a coating on the surface of the epidermis, the color will peel off as you wash your hair and it will return to its original color in about 1-2 months.
Finally, there are permanent dyes that destroy the melanin pigment and settle the desired color into the hair shaft. Unlike the previous two, the color will be permanent unless you cut your hair, but there is a risk of hair damage because it directly affects the cuticle. There are three main substances used in permanent hair coloring. These are ammonia, hydrogen peroxide, and hair dye. The hair cuticle is made up of keratin proteins, which are very stable proteins, so it’s very resistant to chemicals. In order to deposit the pigment into the cuticle, you have to either remove it or open it up to allow the pigment to enter, and ammonia is responsible for opening up the 5 to 15 thin layers of cells that make up the cuticle. This allows the hydrogen peroxide and dye, which must work from the inside of the hair, to penetrate. Hydrogen peroxide works by destroying the melanin pigment in the hair. If melanin, the pigment that gives hair its color, remains in the hair, it“s difficult to achieve the desired color, and it”s difficult for the dye to penetrate, so it destroys the melanin pigment. So, once the melanin pigment is destroyed and the dye we want is in place, the process of coloring is complete. The new pigment settles into the hair cuticle (the dye molecules that have penetrated it undergo a chemical reaction to become larger pigment molecules), and the hair treatment afterwards settles the excited cuticle again, so the pigment doesn’t come out. So, the color doesn’t come out when you wash your hair, and it’s permanent.
There are a few things to keep in mind before proceeding with this type of coloring. The first thing to keep in mind is the type of hair dye you use. Synthetic hair dyes are commonly used because they”re more pigmented and colorful. Synthetic hair dyes are divided into oxidizing dyes, direct dyes, metallic dyes, and natural dyes depending on the type of dye. Direct dyes and metallic dyes are used for temporary or semi-permanent coloring and do not penetrate deep into the hair or cause skin sensitivity, so there are no major caveats, except that they should be cleaned after use. However, oxidizing dyes used for permanent coloring contain a number of substances that can cause allergic reactions. Diamine-based ingredients (p-phenylenediamine (PPD), toluene-2,5-diaminesulfate (TDS)), 2-methyl-5-hydroxy ethylaminophenol (MHEAP)N, N’-bis(2-hydroxyethyl)-p-phenylenediaminsulfate (2HEPPD), p-toluenediamin (PTD), and especially p-phenylenediamine, which is highly antigenic and can cause allergic contact dermatitis, scalp diseases, and hair loss. That’s why it’s important to do a patch test before dyeing your hair to make sure you’re using the right hair dye for you.
Finally, after coloring your hair, you need to take proper care to protect it. Hair is drier and more prone to damage after coloring, so you should use moisturizing hair masks or treatments regularly. It’s also important to protect your hair from the sun by using hair products with UV protection. Since color-treated hair is more sensitive and prone to damage than normal hair, it’s best to use soft brushes and avoid using hot styling tools.
In this article, we”ve explained the structure of hair and how to color it. Although there are differences in the proportions of each person’s hair, it’s roughly 85-90% cuticle, 10-15% keratin, and 10-15% dermal cuticle, and the proportion of substances contained in the cuticle determines the color, thickness, and shape of the hair. The color of the hair depends on the proportion of melanin pigment, and the process of dyeing the hair involves destroying the melanin pigment. This is why hair dyes require hydrogen peroxide, and ammonia is used to allow the hydrogen peroxide and dye to enter the fur. However, ammonia is a strong base, which has a negative effect on the hair and scalp. In addition, the hair dyes that are usually used for hair coloring are organic compounds, which can cause allergic reactions in people with sensitive skin. For this reason, it’s important to test for allergies to hair dyes before dyeing your hair, and be careful to remove any residue afterward.
