One of the major obstacles that Jack faces in his quest to gain control of the boys on the island is his innocence. When he fails to stab the pig he comes across with Ralph in the first chapter, he shows that he is still afraid of crossing boundaries. One of the ways that he finds to escape the things that hold him back is to paint his face.
At first, he believes that painting his face will help him with the hunt. He believes that the change in color will make it so that the pigs don't see him coming. But he quickly realizes there is a greater change available by creating this mask.
He feels this power and begins his dance, a savage rendering of the new strength he feels. When he then orders the boys, his new savage nature is overpowering. As Golding writes, "the mask compelled them."
Jack quickly embraces this new power and it helps to propel him down the path to power and the rest of the boys to savagery.