Hair Coloring 146 pigmented, uncolored hair. These unnatural tones can also be formed when using blonde permanent colorants, but the higher lightening bleach process tends to demonstrate more of this off- tone. It is also more obvious and more orange on dark hair that has been lightened the lighter hair will show a more yellow tone as it is bleached. The reason for the off-tone is not completely understood, but it is thought to be due to a change in color of the melanin as it degrades. The melanin particle size will change as the hair is bleached, which may change the scattering color of the melanin. In addition, the decomposition products of the dihydroxyindole chromophores are also likely to be orange/yellow in color. To cover this orange off-tone color, stylists will often use a Level 2 or semi- permanent product after the bleaching step. The tone of the shade used is often violet or blue to return the hair to a natural brown or blonde color. Other Considerations There are other important considerations to make when investigating the area of hair colorants. Hair Structure Changes from Coloring Products The selection of products available for a consumer’s use varies according to the degree of transformation that they deliver and the permanency of that transformation. For example, the bleach products allow the consumer to lighten her natural color by up to 7 levels (e.g. dark brown to light blonde) and this change is permanent, whereas the semi-permanent and temporary products offer no lightening, a relatively low delivery of color, and color that only lasts for a few washes. The majority of the changes are driven by the oxidation chemistry required to bleach the melanin and form the oxidized dyes. The temporary and semi-permanent products therefore do not significantly change the hair structure. The level of change increases from a demi-permanent to a Level 3 permanent product and then to the bleaches, which give the highest level of change. Table 5 summarizes the pertinent characteristics of these categories of colorants.