Red Seal Hairstylist Practice Exam

Which ingredient is commonly found in products designed for chemically straightening hair?

1. Keratin

2. Sodium hydroxide

3. Silicone

4. Collagen

The correct answer is: Sodium hydroxide

The ingredient commonly found in products designed for chemically straightening hair is sodium hydroxide. This strong alkaline substance is often used in relaxers to break down the protein structure of the hair, allowing it to be reshaped and straightened. Sodium hydroxide works by raising the pH of the hair, which opens the cuticle and allows the chemical to penetrate the shaft, facilitating the straightening process. In contrast, keratin is a protein that makes up the structure of hair and is often included in treatments aimed at smoothing and adding strength to hair rather than straightening it chemically. Silicone is typically used in hair products for its smoothing properties and to provide shine, but it does not have a role in altering the hair's structure. Collagen, another protein, is more often associated with moisturizing and strengthening hair but also does not contribute to the chemical straightening process.