Oklahoma Cosmetology Board Practice Exam

What is the main ingredient in most hair relaxers?

1. Sodium chloride

2. Sodium hydroxide

3. Sodium bicarbonate

4. Sodium sulfate

The correct answer is: Sodium hydroxide

The main ingredient in most hair relaxers is sodium hydroxide, which is a strong alkaline substance. This component works effectively to break the disulfide bonds in the hair's protein structure (keratin), allowing the hair to be straightened. Sodium hydroxide disrupts the natural curl pattern, making it the most common active ingredient in chemical hair relaxers intended for coarse or tightly curled hair types. The choice of sodium hydroxide is crucial because it is very effective at altering the hair's structure, creating a significant and lasting change in texture. Proper use of relaxers containing this ingredient can lead to smooth and straight hair, provided the product is applied correctly and in accordance with safety protocols. In contrast, sodium chloride, sodium bicarbonate, and sodium sulfate serve different functions in hair care products and are not primarily used for relaxers. Sodium chloride is often used as a thickener or stabilizer in hair products, sodium bicarbonate acts as a mild cleanser or pH adjuster, and sodium sulfate is typically used as a surfactant in shampoos. None of these ingredients have the same strong relaxing properties as sodium hydroxide.