Effect of dye and bleaches on hair

1.0    INTRODUCTION
Hair coloring is the practice of changing the hair color. The main reasons for this are cosmetic, to cover gray hair, to change to a color regarded as more fashionable or desirable, to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching. Hair dyes generally contain dyes, modifiers, antioxidants, alkalizers, ammonia and a mixture of other compound used to impart different qualities to hair depending on the hair type, color, and texture. Hair dye is one of the oldest known beauty preparations, and was used by ancient cultures in many parts of the world. Records of ancient Egyptians, Greeks, Hebrews, Persians, Chinese, and early Hindu peoples all mention the use of hair colorings (Feughelman,2015). Early hair dyes were made from plants, metallic compounds, or a mixture of the two. Rock alum, quicklime, and wood ash were used for bleaching hair in Roman times, and herbal preparations included mullein, birch bark, saffron, myrrh, and turmeric. Henna was known in many parts of the world; it produces a reddish dye.
Many different plant extracts were used for hair dye in Europe and Asia before the advent of modern dyes. Indigo, known primarily as a fabric dye, could be combined with henna to make light brown to black shades of hair dye (Draelos, 2012). An extract of the flowers of the chamomile plant was long used to lighten hair, and this is still used in many modern hair preparations. The bark, leaves, or nutshells of many trees were used for hair dyes. Wood from the brazilwood tree yielded brown hair dyes, and another hair dye known in antiquity as fustic was derived from a tree similar to the mulberry (Chandrashekara and Ranganatharah, 2001). Other dyes were produced from walnut leaves or nut husks, and from the galls, a species of oak trees. Some of these plant-derived dyes were mixed with metals such as copper and iron, to produce more lasting or richer shades.