Delaware Cosmetology and Barbering Practice Exam

Chemical straighteners often include sodium hydroxide as a key ingredient. Sodium hydroxide works by breaking down the protein structure of the hair, allowing it to be reshaped and straightened. This ingredient is particularly effective for coarse or curly hair, making it a popular choice in salon treatments for achieving a sleek, smooth look.

The effectiveness of sodium hydroxide is due to its strong alkaline nature, which opens the hair cuticle and allows the chemical to penetrate deeply and alter the hair’s bonds. After the desired straightening effect is achieved, a neutralizing step is typically used to restore the hair's pH balance and reinforce its structure.

While other chemicals like ammonium thioglycolate and potassium hydroxide are also used in various hair treatments (such as relaxers), they function differently and are not the primary choice for chemical straightening. Hydrogen peroxide is primarily used for oxidation processes, such as in hair bleaching or coloring. Thus, sodium hydroxide stands out as the main ingredient specifically utilized in chemical straighteners, making it the correct answer.