The word cosmetic derives from the Greek word kosmetike tekhne,meaning “techniques of dress and ornament”t.hair dyes is most commonly use cosmetics. Which are apply on hair to alter the appearance of hairs. It is the practice of changing hair color without surgical operation .the main purpose of hair dyeing is to cover gray hairs or change to a color regarded as more fashionable and deriable. Hair coloring can be done independently at home or professionally by a hairdresser.hair dyes are popular among men and women .in advance countries about 70% women dye their hair at least once in order to looking different anf attractive from others[ ].Garrote and bonet define hair treatment cosmetic as”the cosmetic products indicated …show more content…
The first synthetic dye is created in 1907 by Eugene Schuller which is a founder of L’oreal.the first home color produced was introduce by firm Schwarzkopf a German cosmetics in 1947.now a days poly color hair dyeing is a multibillion dullar industry that involves the use of both synthetic and plant derived dyes.
Humain hair:
Hair fibers consists of the cuticle and cortex some time medulla is also present in the center of hair fiber. hair fibers are about 50-100µm in diameter. All are composed of dead cells (keratinprotien) humain hair consists aout 65-95% of keratin[ ]and remaining part consist on water ,lipids,pigments and other trace elements. Protein is made up of 20-50 amino acids which formed long chain of amino acids. Cyctine is important amino acid . each unit contains two cysteine amino acids in different chains which lie near to each other and linked by two sulfur atoms,forming a very strong disulfide bond fig1. high amount of disulfide cross-linked gives high mechanical properties.Humain hair color is created by two types of melanin :eumelanin and pheomelanin[ ].eumelanin gives dark and black color and pheomelanin gives blond or red dye[ ]. Fig