The anatomy of hair and the chemistry of hair will be discussed. The use of acidic dyes consisting of small pigment molecules that can slip inside the hair shaft as temporary hair color. The effect of peroxide on the shaft and how it allows shampoo to eventually dislodge the temporary color. The effect of ammonia, if used,will cause the shaft to open and damage natural color. The use of bleach to oxidize melanin and leave a pale yellow color along with peroxide which opens the shaft in alkaline solution to allow the reaction.