What did Jack use to make a mask in chapter 4? Why does he make it for his face, How will the mask change jacks character

From the text:

Jack, concealed from the sun, knelt by the pool and opened the two large leaves that he carried. One of them contained white clay, and the other red. By them lay a stick of charcoal brought down from the fire.

"For hunting. Like in the war. You know--dazzle paint. Like things trying to look like something else--" He twisted in the urgency of telling. "--Like moths on a tree trunk."

He rubbed the charcoal stick between the patches of red and white on his face.

Jack means to use the mask as camouflage. The mask takes Jack further into barbarism.