The Advanced Art of Stop-Motion Animation: Building Puppets: Part 3
Another method for getting the silicone into the mold is to leave both halves of the mold open, mix a batch of silicone, and start by pouring a thin layer directly into the mold cavity. This is essentially skinning the impression of the sculpt in the mold and creating the outer layer of the cast, so it’s important to get into every nook and cranny of the mold and avoid trapping any air bubbles inside. After skinning the mold, more silicone is poured into the mold to fill it up, and the armature is rested on top of the setting silicone in exactly the right suspended position. Within a few minutes, depending on the pot life of the silicone, the first half will begin to cure. Meanwhile, the second half of the mold is skin-coated and filled in with more silicone. Then, the first half of the mold with the armature in it can be flipped over, pressed onto the second mold, clamped shut, and left to cure completely. All of the silicone will bond with itself inside to create the bulk of whatever you are casting.
Once the silicone is cured, the mold is pried open to reveal the cast of the original sculpt, with its armature living inside and totally flexible for animation (Figure 3.66)! The next step is to trim off any extra flash of thin silicone that may have spilled over the mold cavity. This can be done with fine scissors to trim it right up to the edge of the seam. To help conceal the seam a bit more, it may help to cut a groove into the edge and patch it up with a thin layer of silicone. During this setting time before it completely cures, continual patching, smoothing, or texture stamping can still be worked into the surface, depending on the design and look you are after.
In another example, for Ava’s neck, an additional piece of silicone is cast to form a shape similar to a shirt dickie to go under her clothes (Figure 3.67). The shape itself is sculpted in clay, and the first part is molded upside-down so that the second half can be molded around it right-side-up. The result is a thin, flexible neck piece that has been shaped to fit around the armature over her shoulders.