Not only would the puppet’s foam head soak up the water like a sponge, but the water eventually would wash away the flocking sprayed on the character, discoloring the puppet and leaving a scrim of flock shavings floating on the surface. Before a single frame of film could be shot, then, the Muppet builders had to figure out a way to design a waterproof, colorfast, flexible puppet for Oz to work with.