Silicone rubber is an ideal material for making molds of fossils and other rigid objects. Like liquid latex, it yields a light, flexible, high-fidelity mold, but has the added advantages of longer life and resistance to chemicals and decomposition. It is the recommended material for making long-lasting molds of important specimens. A silicone mold also can be made in less time than an latex mold, if "fast" catalysts are used. Among silicone's few disadvantages is that it is considerably more expensive than latex, and not quite as elastic or tear resistant.

Before making a silicone rubber mold for the first time, you’d better get an overall understanding of the procedures and techniques. I make no guarantees for any of the products or methods described herein, but have used them successfully in the past. Note that some silicones may slightly discolor some rock types. The reader is encouraged to test and experiment with unimportant specimens before using them on valuable subjects. The procedures may seem complicated at first, but become relatively simple with practice.