What type of product is typically recommended to add volume to hair?

Thickening mousse is typically recommended to add volume to hair because it is specifically designed to create body and lift. Mousse contains ingredients that provide hold without weighing the hair down, enabling it to maintain a fuller appearance. When applied to damp hair, thickening mousse helps to enhance texture and is particularly effective for fine or flat hair types. It works by coating each individual hair strand, making them appear thicker and promoting an airy lift at the roots when styled.

Leave-in conditioners, on the other hand, primarily focus on moisturizing and detangling the hair rather than providing volume. Serums usually aim to add shine or reduce frizz and can sometimes weigh the hair down, hindering volume. Hair oils are more suited for hydration and nourishment, which can make hair softer but may not contribute to volume as they can also weigh the strands down. Thus, thickening mousse stands out as the ideal choice for adding volume to hair.