Why do tattooist wipe Vaseline or ad on stencil before tattooing?

Tattooists apply Vaseline or a similar barrier over the stencil before tattooing to help the stencil adhere better to the skin and prevent it from smudging or wiping away during the tattooing process. This layer creates a smoother surface, making it easier for the tattoo needle to glide and ensuring more precise lines. Additionally, it helps keep the skin moisturized, reducing irritation and promoting a better healing process.