* Add shine: It's primary purpose is to create a glossy, shiny finish.
* Enhance color: It can intensify existing color, add subtle tones, or refresh faded color. It's not a permanent dye, so it won't significantly change the base color.
* Smooth the hair cuticle: By coating the hair shaft, it can help to smooth down the cuticle, reducing frizz and making hair feel softer.
* Condition: Some cellophanes contain conditioning ingredients that help to moisturize the hair.
Think of it like a topcoat for your hair.