What is an example of a chemical service offered in barbering?

Hair coloring is an example of a chemical service offered in barbering because it involves the application of chemical solutions to change the color of the hair. This process can alter the hair's structure by penetrating the hair shaft and interacting with the pigments, thus requiring a thorough understanding of the chemical properties, techniques, and safety protocols associated with these products.

Beard trimming, shampooing, and haircutting do not involve chemical processes. Instead, they are primarily mechanical services that focus on the physical alteration of hair without changing its chemical composition. Therefore, hair coloring stands out as the only option that employs chemical manipulation, making it a specialized service within the range of barbering practices.