Why is a clarifying shampoo sometimes recommended before a perm?

A clarifying shampoo is recommended before a perm primarily to eliminate product buildup, which can interfere with the perm's effectiveness. When hair products accumulate on the hair strands, they can create an invisible barrier, preventing the perm solution from penetrating the hair effectively. This buildup may reduce the ability of the hair to absorb the perm solution, leading to undesirable results such as uneven curls or a lack of curl formation altogether.

Using a clarifying shampoo helps to thoroughly cleanse the hair, ensuring that it is in the best possible condition to absorb the perm solution. It removes not only styling products but also oils and other impurities, allowing for a more uniform application and ensuring that the chemical process of curling the hair can work effectively.

The other choices do not align with the primary purpose of using a clarifying shampoo before a perm. For instance, enhancing hair color retention, improving elasticity, or adding moisture are not directly related to the perming process and can actually complicate the chemical procedure if the hair is not cleansed of buildup first.