The Advanced Art of Stop-Motion Animation: Building Puppets: Part 3
Foam latex has long been a popular material for creating the outer skin or entire body of a stop-motion puppet over its armature. The basic elements that are needed for a foam latex puppet are the sculpt (the official term for the original clay sculpture of the puppet) and a plaster mold formed around the sculpt. The foam latex goes inside the mold along with the armature and becomes a cast replica of the sculpt. Foam latex comes as a series of about five different liquid agents that are mixed together to gel into a soft, spongy material. Once it is cured by baking it in a convection oven, it basically behaves like upholstery foam, which springs back into shape even after touching it. Although foam latex is stinky and tricky to mix properly, it is relatively easy to repair and very lightweight, which are both important qualities for a stop-motion puppet.
Another material that has become very popular in recent years for puppet fabricators is silicone. Silicone is easier to mix than foam latex (only two agents are needed, instead of five) and can be used to create both puppets and molds. The appearance of silicone skin for a puppet has a different quality than foam latex; it can potentially be smoother and more translucent. Although foam latex can be cast and painted to appear very smooth, it will often have a certain degree of texture to it. The smoothness and attention to detail from the original sculpt that silicone provides gives a great deal of creative freedom for different character designs. The other advantage that silicone has is that it will only stick to itself, so it can be worked with alongside a variety of other materials. At the same time, there are some materials that do not react well with silicone, including latex and any sulfur-based modeling clays.
When working with silicone or any other chemicals, it’s important to understand what you are dealing with. By law, safety sheets must be provided and sent along with any chemicals you purchase or order, and it’s important to read them carefully before cracking the chemicals open. Safety precautions and guidelines will typically tell you to protect your skin, lungs, and eyes from the material, so rubber/latex gloves, masks, and safety glasses are very important to have on hand. The instructions will also tell you how long you can work with the product before it starts changing. The time span for working with silicone before it sets (and is no longer in a pourable liquid form) is referred to as its pot life; its cure time is how long it takes to cure fully. Pot life is usually only a few minutes, and cure time is typically 24 to 48 hours. Silicone comes in at least two liquid parts that need to be mixed together: the inert silicone base and an additional 10% of an activating agent that causes it to solidify. There are also softening or retarding agents you can buy that can be mixed in to change the silicone’s consistency or slow down its pot life, but these are only necessary if you want additional control over it. Once these different agents are one uniform color after mixing (in a cup or bucket, with any kind of stirring tool), you know it’s ready to start using before it sets.