Hair color, along with skin tone, is one of the most defining aspects of personal appearance. Like skin tone, hair color results from the presence of the natural pigment melanin, and is determined by genetics. Although hair color is generally associated with different ethnic groups, there is also a great deal of individual variation, making each person’s specific hair color and shading unique. Hair color also changes over time: Some children have blond or red hair that darkens around puberty and, of course, grey hairs begin to appear far too soon for most people. Fortunately, both men and women can change the color of their hair, and have been doing since the beginning of recorded history.
Melanin, the natural pigment that gives hair its color, is produced by melanocytes located at the base of the hair follicles. Two different types of melanin are produced: eumelanin and pheomelanin. There are also two different sub-types of eumelanin, called black and brown. Pheomelanin is associated with lighter shades, while eumelanin colors hair darker. The amount and ratio of each type of melanin determines the color of the hair shaft. Not all melanocytes on a person’s head produce exactly the same ratio of pheomelanin and eumelanin, however; each strand of hair has a subtly different mix of color, which gives the overall color of a head of hair a natural variation. Some melanocytes do not produce any melanin at all; this produces hair that is usually called “white” (although it is actually clear, but appears to be white because of the way light refracts through the shaft). When non-functioning melanocytes are scattered throughout a scalp, the effect known as “salt and pepper” hair is produced.
Hair can change color naturally as the melanocytes change the ratio and level of production of melanin. Hormonal changes that occur with puberty can cause hair color to change (usually becoming darker), but some types of medical conditions or exposure to certain chemicals can also produce changes. Exposure to sunlight can also cause pheomelanin to break down, causing hair to look lighter, an effect known as “sun bleaching.” With age – usually in the early to mid-20s for men and the late 20s for women – melanocytes can begin to stop producing melanin, causing the hair to become grey.
Since hair is such a prominent feature in a person’s appearance, hair coloring for cosmetic reasons has been practiced for thousands of years, in virtually every known culture. Generally speaking, there are three main methods of hair coloring: permanent, semi-permanent and surface coloring. Permanent coloring involves bleaching out the natural melanin with some type of oxidizing agent, usually hydrogen peroxide, and then replacing the color with a dye. To allow the dye to be absorbed through the outer layer of hair (the cuticle), an alkaline preparation (usually ammonia) is used to open the pores of this layer. Although the color of the hair shaft is permanently changed, as the hair continues to grow its natural color is revealed in the new hair at the base (the “roots”). This method can also damage the hair, since it changes the structure of the cuticle, making it weaker, and strips off the natural hair oils (sebum) that give hair its gloss and shine.
This method gives the hair a uniform color, which can look unnatural, so highlights (a second and even a third color) are usually applied to provide an attractive variation in the hair. Several techniques are used to make highlighting (and lowlighting, making some areas darker) look as natural as possible. Foiling covers selected parts of the hair, while the balance is treated. Capping involves placing a tight-fitting cover over the hair and drawing some strands through holes in the cover for additional treatment. Balayage is a direct, freehand coloring of areas of the hair to create color variation.
Semi-permanent hair coloring does not bleach out the natural melanin and uses a weaker alkaline to allow the dye to reach the inner core of the hair. This is less damaging to the hair and, since the dye only modifies the existing melanin, a natural variation in hair color looks more natural. The draw-backs are that hair cannot be dyed a lighter shade, only a darker, and the treatment will only last through approximately for 4 to 5 shampoos.
Several temporary systems of hair coloring are used for very short-term hair coloring. With these, hair dye is applied in rinses, shampoos, gels, sprays and foams which have pigments which do not penetrate the cuticle layer. These wash off with the first shampoo, which make them an attractive alternative for bright, vibrant colors – including some not naturally found in human hair – for special events.
Although hair coloring is a popular technique for many people, both men and women, there are side effects that have to be considered. Over-treating hair can make the shafts brittle, causing breakage and split ends. Hair can also become dry, as the sebum layer is disrupted. There are also times when hair dyes can react in an unexpected way, causing the resulting hair color to be much different than intended. Even temporary hair coloring has been known to permanently affect the color of melanin in the hair shafts.
While the formulas for most commercial hair coloring systems are carefully designed not to damage the skin on the scalp, some individuals do experience contact dermatitis from the use of hair dyes and associated chemicals, causing itching, redness and even skin peeling. Other people may have allergic reactions to dyes and coloring chemicals. Although medical studies have not shown any direct hazard associated with hair coloring for women who are pregnant or nursing, some unregulated homemade coloring methods may cause unintended consequences. As with any skin or hair treatment, if you experience any adverse reactions while using a product, you should consult a physician.
Additional Hair Care Resources:
SkinStore Hair Concerns Library
Hair Care Products
Hair Styling Products
Hair Care Supplements
Hair Care Tools
Hair Care Treatments