What defines an alkaline substance?

An alkaline substance is characterized by a pH level above 7.0. The pH scale ranges from 0 to 14, where values below 7 indicate acidity and values above 7 signify alkalinity (or basicity). Thus, any substance that has a pH greater than 7 is considered alkaline. This concept is fundamental in various fields, including cosmetology, where alkaline products can influence the hair and skin's pH balance. Understanding the pH levels of products helps professionals determine their effects, such as their ability to open the hair cuticle or neutralize unwanted acidity. The definition of alkalinity as having a pH above 7 supports the application's relevance in practices such as hair coloring, perming, and other chemical treatments.