What common chemical is used to lighten hair?

The chemical commonly used to lighten hair is hydrogen peroxide. This substance works as an oxidizing agent, breaking down the natural pigments in the hair, particularly melanin, which is responsible for its color. When applied to hair, hydrogen peroxide creates a bleaching effect, allowing for a range of lighter shades, from subtle highlights to full bleach applications.

In the context of hair lightening, hydrogen peroxide is often found in various hair bleaching products and can be used in combination with other colorants to achieve the desired shade. Its effectiveness and ability to penetrate the hair shaft make it a popular choice among professionals and consumers alike for achieving lighter hair tones.

The other substances listed do not serve the same purpose. Salicylic acid is primarily used for its exfoliating properties in skincare, helping to treat acne, while chlorine is commonly associated with swimming pools and can actually damage hair rather than lighten it. Glycerin, on the other hand, is a humectant used primarily for moisturizing and conditioning hair and skin but does not have any lightening properties.