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Home >> Hair Coloring >>Permanent hair coloring Permanent hair coloring techniques have received the greatest popularity among all other coloring procedures. It accounts for about 70% of all hair dye sales. These permanent dyes are able to lighten or darken natural hair color and can easily cover large amounts of gray hair. Also, they are able to produce a long lasting effect on the hair color . They are readily available in any retail store in almost any shade, from natural colors to exotic greens, reds, blues or purples. Components of permanent dyes Permanent hair-coloring dyes consist of three components. They are:
Among these three components, the primary intermediates and couplers are packaged together and are mixed with hydrogen peroxide immediately before application to the hair. Mechanism of the hydrogen peroxide in permanent dyes Hydrogen peroxide diffuses the melanin, and lightens the natural color of hair. After lightening the natural hair color it develops the dyes and allows the dyed color to deposit in the hair fiber. The natural color of the hair and the color that is required determines the volume and quantity of the hydrogen peroxide to be used. If a mild color that is lighter than normal hair color is required then the strength of hydrogen peroxide has to be increased in the dye preparation. Application procedure of permanent hair color Permanent hair coloring techniques are performed with alkali solutions which allow the penetration of the chemicals through the cuticle layer. The alkaline reaction causes the cuticle to lift up, allowing hydrogen peroxide and dye to enter the cortex. After entering it gets deposited in the hair fiber and gives color to the hair. The color is usually kept on for 20 to 40 minutes and then washed with a neutral or slightly acid after-rinse which stops the alkaline reaction, allows the cuticle to close, and traps the color molecules inside. Most of the permanent dyes contain conditioning agents which help in reducing hair damage. Conditioners are very much essential after any kind of synthetic coloring or chemical hair treatments like curling. It is recommended to apply the permanent dye on the same day when it is mixed in order to avoid adverse chemical reactions. Dyes with lower pH are less damaging to the hair, but the resulting coloring is not very strong. The most commonly used permanent coloring hair dyes The modern permanent dyes consists of solutions of paraphenylenediamine (PPD), or similar “para” compounds. These para dyes are formulated together with other substances, such as surfactants, solvents, thickeners, antioxidants, and metal chelating agents which ensures easy use and safe storage. Para dyes are manufactured in three forms; cream, liquid and gel. The hydrogen peroxide is packaged separately and is mixed with the dye preparation just before use. Before the application of a para dye it is recommended to test it on a small portion of scalp to find out if the skin of the skin of the scalp is allergic to the dye. Mechanism of the permanent para dyes These permanent para dyes are water soluble and have comparatively small colorless molecules, which can easily penetrate the cuticle and enter the cortex. The oxidant used here is again hydrogen peroxide, that makes the mixture colored when mixed with the colorless molecules. When this mixture is applied on hair, insoluble molecules settle in the hair cortex. They are too large to pass through the cuticle and therefore do not wash out easily. Effects of permanent hair coloring techniques The effects of permanent color are long lasting when compared to semi-permanentor temporary dyes. But there are many factors that influence the intensity of permanent hair coloring such as concentrations of dye and peroxide, higher temperatures and the pH of the dyes. Although hydrogen peroxide allows the formation of color, it is also able to destroy it. Permanent hair coloring should only be done when the previous coloring effect has faded. Also, there should be equal application of color on every hair strand. Care is required to balance color on newly growing hair with the hair that is already dyed. Though permanent coloring is largely popular due to its long lasting effect, remember that it can damage the hair if used in excess. Also, the permanently colored hair requires good hair loss shampoos in order to prevent excess dryness. References: Chantal Bolduc, Jerry Shapiro, “Hair Care Products: Waving, Straightening, Conditioning, and Coloring”, 2001, Clinics in dermatology, 19:431–436 John Gray, ”Hair Care and Hair Care Products”, 2001, Clinics in Dermatology;19:227–236 |
