What chemical process do smoothing treatments generally involve?

Smoothing treatments primarily involve the process of applying keratin, a natural protein that helps to strengthen and smooth hair. Keratin treatments work by infusing the hair shaft with this protein, allowing the cuticle to lie flat and leading to a reduction in frizz and an increase in shine. The treatment typically involves applying a keratin-rich solution to the hair, followed by the use of heat to lock the keratin into place. This process effectively modifies the structure of the hair, making it more manageable.

While deep conditioning can also improve hair texture and appearance, it does not fundamentally alter the hair's structure like keratin treatments do. Hair relaxing specifically targets curly or wavy hair to permanently straighten it through the breakdown of protein bonds, which is not the primary goal of smoothing treatments that focus on enhancing the hair's natural texture. Coloring does not directly relate to the smoothing process, as it primarily alters hair color rather than its texture.

Thus, the focus of smoothing treatments on the infusion of keratin makes this option the correct choice in the context of their chemical process.