What type of service involves the use of a straight razor?

The use of a straight razor is primarily associated with shaving services. This technique involves the careful and precise handling of the razor to achieve a closely shaved result, often required for men's grooming. A straight razor allows for different styles of shaving, including the classic straight shave, which can give a very smooth finish that would typically be desired in high-end barbershops.

In contrast, haircutting focuses on cutting hair with shears or clippers rather than a razor, while facial treatments generally involve skincare procedures, often using various products but not typically involving the use of a razor. Hair coloring is a complete different process that involves applying dyes or chemicals to hair, without any connection to shaving techniques. Therefore, the correct answer emphasizes the specific service in which a straight razor is a key tool: shaving.