New Mexico Cosmetology Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

The most appropriate product to protect hair during thermal styling is a heat protectant spray. This type of product creates a barrier between the hair and the high temperatures from styling tools such as flat irons, curling irons, and blow dryers. Heat protectant sprays typically contain ingredients that help to reduce moisture loss and provide a shield against damage, thereby minimizing breakage and maintaining the hair's overall health while styling.

Other products listed do not serve the same protective purpose during thermal styling. Moisturizing serums are primarily intended to hydrate and nourish the hair but do not provide adequate protection from heat. Hair gel is used mainly for styling and hold, without any thermal protection properties. Hair dye is used for changing hair color and does not offer any benefits related to heat protection. Therefore, for anyone looking to protect their hair during the application of heat, a heat protectant spray is the most suitable choice.