Dyeing Human Hair

Abstract

The different types of dyes described for human hair include, permanent or oxidation dyes, semipermanent dyes, temporary dyes or color rinses and other types of dyes either proposed for or used on human hair. The mechanism of oxidative dyeing of human hair is presented in detail describing a large number of different dye precursors and couplers and how they combine to form different dye species. Hydrogen peroxide and the new peroxymonocarbonate oxidative systems are presented. Different matrix compounds used in hair dyeing are also included. Regulatory activities related to oxidation hair dyes, described in this chapter, focus on the European community which has been the most active in the regulation of oxidation dye ingredients and provides periodic updates on the COLIPA website for safe and banned hair dye substances. Because of the increase in the aging population and the global sale of hair dye products to the graying population, a review of the initiation of hair graying including the age at which graying begins for different populations, the incidence of graying versus age in 5 year increments for different populations and graying among different geo-racial groups are also presented. IntroductionBecause of the increase in the aging population and the resultant graying of hair for all peoples of the world, the global sale of hair dye products has been increasing at a faster rate than many other hair care products. Therefore, a review of the incidence of hair graying, graying versus age and graying among different geo-racial groups is presented at the end of this chapter. Other areas of new research for this edition described in this chapter include a means to minimize hydroxyl radical in oxidative hair dyeing, a new oxidative system and photoprotection of hair proteins. Fading of artificial hair colors and effects of photofilters on fading, regulatory methods, hair shine effects and dyeing, and a novel method for producing permanent dyed hair using dye-metal ion complexes have also been included.

Coloration, Hair

“…At a pH greater than the isoelectric and isoionic points, hair bears a net negative charge [3,4,20,28] and vice versa at a lower pH. Hence cationic dye species display affinity for hair under alkaline conditions [3,4,10], and anionic dye species display affinity for hair under acidic conditions (see Fig. 3).…”

“…As their names imply, these classes are based on the resistance of the dyes to removal during shampooing or their "permanence." In this regard, temporary dyes last through only one or two shampoos, while semipermanent dyes last up to six shampoos [4,5,10,11]. Permanent dyes essentially last until new hair growth appears, which is every 4-6 weeks for the average consumer [3,11,12].…”

“…In each case, some dye can remain adsorbed onto the surface of hair [11,13]. Dye adsorbed onto the surface or within the outer layers of hair can more easily be removed upon shampoo treatment [1,4,5,[9][10][11], especially if dye is weakly bound and the cuticle is damaged (more porous).…”

“…Couplers, which are essentially colorless, are known as color modifiers, because they play a role in determining the final color achieved [1,3,5,30]. Direct (non-oxidative) hair dyes may also be included in the formulation of permanent dyes to function as "color agents" that modify the color directly [10], enhancing vibrancy [1]. Examples of color agents are C.I.…”

“…Examples of color agents are C.I. Disperse Blue 1, 2-nitro-p-phenylenediamine (red), and 4-nitro-o-phenylenediamine (yellow-orange) [10].…”