The effect of Jack masking himself with clay and charcoal is that it gives him a sense of anonymity and power. The purpose of any mask, real or imagined, is to hide one's true identity and to give the wearer a sense of power and control. Yes, all people wear masks from time to time, whether it is a physical mask or an emotional mask. People wear masks to protect themselves from the outside world, to hide their true feelings, and to present a different version of themselves to the world.