New Mexico Cosmetology Practice Exam

What is the primary ingredient in most hair relaxers?

1. Hydrogen peroxide

2. Sodium hydroxide

3. Silicone

4. Glycerin

The correct answer is: Sodium hydroxide

The primary ingredient in most hair relaxers is sodium hydroxide. This chemical, also known as lye, acts as a powerful alkaline agent that breaks down the disulfide bonds in the hair's keratin structure, which results in a straightening effect. Sodium hydroxide is highly effective in altering the hair's texture, making it easier to manage and style. When applied to the hair, sodium hydroxide raises the pH level, encouraging the hair fibers to swell and soften, thus allowing the structural changes to occur. It is important to handle sodium hydroxide with care due to its caustic nature, as it can cause burns if it comes into contact with the skin. The other ingredients listed, such as hydrogen peroxide, silicone, and glycerin, play different roles in hair care and styling products. Hydrogen peroxide is generally used as a bleaching agent, silicone is often included to provide smoothness and shine, and glycerin acts as a humectant that helps retain moisture. However, none of these ingredients serve the primary function of relaxing hair like sodium hydroxide does.