Lord of the Flies, by William Golding, is a particularly symbolic novel, and the face-painting which Jack and the other hunters do is certainly more significant than just serving as simple camouflage they use to hunt pigs.
Jack is the first boy to paint his face (chapter 4), and he does so initially because he thinks the pigs are seeing him rather than smelling him, which keeps his hunts from being successful. It is a rather startling sight for the other hunters, at first, to see the red, white, and black paint all over Jack's face; however, Jack is mesmerized as he looks at his painted-face reflection in the water.
He looked in astonishment, no longer at himself but at an awesome stranger. He spilt the water and leapt to his feet, laughing excitedly. Beside the pool his sinewy body held up a mask that drew [the others'] eyes and appalled them. He began to dance and his laughter became a bloodthirsty snarling. He capered toward Bill, and the mask was a thing on its own, behind which Jack hid, liberated from shame and self-consciousness.
Throughout the rest of the novel, Jack's painted face is almost always referred to as a mask; and, as this quote indicates, this mask serves to insulate him from "shame and self-consciousness." The result is a "bloodthirsty snarling" hunter who has become a killer and does not care who or what he kills, for once these restraints of civilization are removed, anything becomes acceptable. Soon the rest of Jack's "tribe" will wear the paint and become Jack's followers in crime, and nearly all civilized behavior is lost.