A facial is easy, right? It's on your face, so there's no need to get undressed — but that's not always the case. "[Facialist] Joanna Czech famously said that your face starts at your nipples, and as hilarious as it sounds, it's true," said Sofie Pavitt, celebrity aesthetician and OleHenriksen brand ambassador. "The decollate is as sensitive and delicate as the skin on your face, so I always want to treat that area. I provide robes at my studio, which keep my client comfortable and gives me access to the decollate, neck, shoulders, and back as well as the face."
If you're in a private room, you may be asked to lie under a towel or put on a robe. That means you can take off your shirt and your bra (if it's not strapless) if you're comfortable with that.
At facial bars, where you're likely sitting next to someone else in close vicinity, you should wear a shirt with a low neck like a tank top or strapless top but keep your clothes on. This allows you to experience the full treatment without your clothing getting in the aesthetician's way.