Chapter 4 151 generally improves hair feel and provides the hair increased protection from brushing and combing damage. There has been increased interest in the last five years in developing technologies to protect against damage during the coloring process. Products that reduce the pH of coloring products will decrease perhydroxyl anion formation and thus reduce F-Layer removal and cystine oxidation. However, lightening and color formation are also often reduced this is not desirable. The recent introduction of the peroxymonocarbonate ion as an oxidant has demonstrated that lightening can be maintained at the lower pH of 9 with coloring performance equal to current products that bear a pH of 10. The product also contains glycine as a radical scavenger to remove any formation of the reactive carbonate radical. The colorant gives significantly lower F-Layer removal and free radical formation.38 Chelants that target copper and iron in the cuticle have also recently been shown to be effective at reducing damage during the coloring process. Chelants such as ethylenediamine disuccinic acid have been shown to bind the low levels of copper in hair even in the presence of ~10x excess calcium ions and to prevent formation of hydroxyl radicals on the surface of the hair.39 Color Fade Dyes will fade over multiple washes and the rate at which the color is lost will depend on the structures of the dyes. There are two main processes for color fade: UV exposure and washing out of the dyes during shampooing.40 Typically the biggest contributor to fade is washing, but UV fade can be important at high levels of sun exposure. Wash fade will be faster for the temporary and semi-permanent direct dyes than for oxidative dyes in the demi- permanent and permanent products. In addition, some of the tones of oxidative dyes fade faster than others, e.g., the vibrant red tones. This is generally due to the lower molecular weight and increased water solubility of the tonal oxidative dyes.