Final answer:
Hair lightening is known as bleaching or decolorizing, involving the use of hydrogen peroxide to remove the natural pigment from hair, resulting in a permanent lighter color.
Step-by-step explanation:
Hair lightening is commonly known as bleaching or decolorizing. This process involves the chemical reaction of lighteners such as hydrogen peroxide with the natural pigments in the hair, removing the color and resulting in a lighter shade. The term 'bleaching' is often used because hair is typically treated with solutions like diluted hydrogen peroxide, which act as an oxidizing agent. The process of oxidation dyes follows several steps, starting with the oxidation of 1,4-diaminobenzene derivative to the quinone state, followed by the reaction with a coupler compound, and ending with the final dye.
Bleaching is a permanent change because it removes the natural pigment of the hair. As such, semi-permanent hair color products cannot lighten hair, since they do not lift the original color. Diluted H₂O₂ (hydrogen peroxide) is commonly used for hair lightening and is also known as 'peroxide blonde' when referring to the resulting hair color.