In chapter four, Jack paints his face using red, white, and black pieces of charcoal, which creates a horrific mask that initially frightens his hunters when they see him for the first time. Golding writes,

the mask was a thing on its own, behind which Jack hid, liberated from shame and self-consciousness (89).

Golding's description of Jack's mask is significant and his painted face essentially allows Jack to embrace his unrestrained, primitive nature without feeling self-conscious or guilty for behaving like a complete savage. Prior to wearing the painted mask, Jack experienced feelings of shame and was somewhat embarrassed for behaving uncivilly. Jack's perspective and ability to completely embrace his savage side changes after painting his face. He feels removed from his despicable actions and comfortable committing barbarous acts of violence while hiding behind his painted mask. Overall, the painted mask liberates Jack and allows him to fully embrace his savage, primitive nature without feeling embarrassed or ashamed. With his faced painted, Jack becomes an unrestrained, violent savage.

In Lord of the Flies, Jack represents the Id, or the unconscious, in his desire to be chief, to rule, and to implement his power with violence. When hunting, Jack finds himself unable to kill a pig because of the violence of it; however, his desire to be seen as leader by the other boys allows him to overcome this disgust by hiding his humanity behind a mask of mud and leaves:

Beside the pool his sinewy body held up a mask that drew their 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.
(Golding, Lord of the Flies, gv.pl)

The mask, hiding his face, allows his Id to rule his Ego, and shows his true nature; without it, the other boys can see Jack, who is just like them. With the mask, however, he is something more, and feels capable of accomplishing more, but his inner nature creates unnecessary violence instead of leadership.

What does the mask allow Jack to do in Lord of the Flies?

The mask seems to mark the difference for Jack between civilized society and a savage lifestyle. Once shed of civility, Jack is free to declare himself a leader, determine to be carefree, and decide that the beast is real whether he is real or not.

Dressed as a choir boy, Jack remained content with Ralph's rule which demanded order and responsibility. Behind a mask and colors of savage paint, Jack grew able to kill the pigs, and to eventually kill man. Jack maintained the allegiance of most of the boys by crafting an image of the carefree lifestyle that was attractive, but not responsible.

This mask and division is important because in society today, it is easy for us to likewise appear different in order to shed some of our values. In front of people we respect we often maintain our values. This piece is a cautionary tale to help us beward of the times in life when we place the mask on our face just like Jack.

How does the mask allow Jack and his hunters to behave differently in Lord of the Flies?

The significance of the masks in the Lord of the Flies is that they allow the boys to transform themselves from school boys to hunters.  Even though the transformation happens on a superficial level at first, the masks give the boys confidence to act more fierce, more savage in keeping with their new outward appearance.  When Jack first sees himself in the reflection of the water in the coconut shell, he suddenly feels like a different person, "an awesome stranger" (63). 

Jack realizes that wearing the mask and hiding his true appearance frees himself from old expectations.  If he looks like that "awesome stranger," then perhaps he can act like him too; the mask became "a thing on its own, behind which Jack hid, liberated from shame and self-consciousness" (64).  Jack, and the other hunters as well, are able to shed their inhibitions wearing the masks, which empower them to commit acts that they would not have been capable of as simple English school boys.