Freeman, Lacey, and Kahler's death scenes were created using different models. A mold was made of Kahler's face; it was lined with bladders filled with air. Controlled by up to ten people, the air was removed to make the head shrivel. Special effects artist Chris Walas sculpted Lacey's melting face using different colored layers of gelatin placed over a carved, heat-resistant stone skull. Propane heaters were used to melt the gelatin and filmed using a slower-than-normal camera so the effect appears to take place rapidly when played at normal speed. Belloq's head mold contained a thin-plaster skull filled with blood bags and detritus. It was blown up using explosives, shotguns, and an air cannon. It took three attempts to get the desired effect. Belloq's death was considered so extreme the Motion Picture Association of America initially classified the film with an R rating restricting it to those over the age of 17 without an adult. Flames were superimposed over the scene to conceal the effect.