What do alkaline solutions do to the hair?

Alkaline solutions are known for their ability to soften the cuticle, which is the outermost layer of the hair. When hair is treated with an alkaline solution, the pH level increases, causing the cuticle layer to swell and lift. This process allows for better penetration of other products, such as color or treatments, into the hair shaft. Softening the cuticle is crucial during chemical processes as it prepares the hair to accept these treatments more effectively, enhancing the results.

The other options, while related to hair treatment, do not accurately describe the primary effect of alkaline solutions. Strengthening the cortex refers to internal hair structure, generating heat is a characteristic associated with certain chemical reactions but not specifically with alkaline solutions, and protecting from damage would imply a preventive measure rather than a reactive treatment effect. Understanding the specific impact of alkaline solutions helps in effectively applying various hair treatments.