It may surprise students to learn that gutta-percha, shellac, and the horns of animals—all naturally occurring substances—were used as plastic material before the first synthetic plastics were produced. Gutta-percha is derived from the sap of certain trees, and shellac is made from the secretions of a tiny scale insect. Before horn can be used, however, it must be "plasticized," or softened, by being boiled in water or soaked in an alkaline solution.