This procedure is performed either at sub-freezing or room temperature, depending on the polymer and crosslinker used. The vacuum makes the more volatile acetone evaporate, allowing the polymer to replace it. At this point, slices are clamped between two glass plates and cast by adding polymer. The glass plates are then dismantled from sections. Overall, the kind of polymer used determines the optical and mechanical nature of the results.
Epoxy resins produce very firm products and so are used for thin, transparent body or organ slices.
Polyester is the polymer of choice for brain slices because it preserves the visual distinction between gray and white matter. The value of using plastinated bodies and organs in the classroom is hard to dispute. Glover's laboratory, for example, has prepared several frogs and rats for two high schools in Michigan. And because these specimens can be used almost indefinitely, they help reduce the number of animals killed for dissections each year. What is debatable, some people maintain, is the use of plastinated bodies as a form of art.