Hair Coloring 124 There is evidence that it is oligomers of these intermediates that are formed during melanogenesis in the follicle to give the intense color of the melanosomes. The detailed structure of the melanosome granule is still not fully understood but it is known that the outside of the granule is a single lipid layer inside of which is a protein backbone on which the melanin chromophore forms.6 Figure 2 shows an SEM image of a eumelanin granule. To lighten the hair the melanosome structure needs to be broken up and the chromophores destroyed, and the combination of the oxidant and alkalizer determines the effectiveness of this process. For Level 3 permanent colorants the oxidant is hydrogen peroxide and the alkalizer is typically ammonia. Both hydrogen peroxide and ammonia can readily penetrate into the cortex of the hair to reach the melanin, and at the alkaline pH of the product (pH 10), the active species is the strongly nucleophilic oxidant perhydroxyanion (HOO-) formed from the deprotonation of the hydrogen peroxide (Eq. 1).7 H2O2 HOO- + H+ pKa = 11.3 Eq. 1 Figure 2 SEM micrograph of eumelanin granule