After the body is dry, you can pop the balloon and mark up the head.



This point is very crucial - you have to make sure that there are no serious weak spots on your paper mache-ing. This is critical because the paper will have to withstand some abuse from people patting your head, spilling drinks, people trying your head on, and others.



One way to check is to hold the head up to a light, or to put a flashlight on the inside and look for light spots. I made the mache approximately a 1/8th of an inch (2-3mm) thick.



Also, you're going to be making cuts to the mache, so you'll inherently weaken the overall integrity.